Vitamin D
Research reviewed: up until 10/2023
Vitamin D (Cholecalciferol (D3)) is a dietary supplement with 64 published peer-reviewed studies involving 12,913 participants, researched for COVID-19, Autoimmune disease, Diabetes and 1 more areas.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
COVID-19
StrongAutoimmune disease
ModerateDiabetes
ModerateDementia
ModerateResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
COVID-19
To investigate whether Vitamin D treatment can reduce the associated risk of COVID-19 infection. Subjects: 220,265 American veterans supplemented with vitamin D3 (cholecalciferol or calcifediol) 34,710 supplemented with vitamin D2 (ergocalciferol or doxercalciferol) 407,860 untreated patients (control)
Study Type
Retrospective cohort study. This type of observational study in which a group of individuals with a common exposure are compared to another group of individuals using historical records.
Purpose
To investigate whether Vitamin D treatment can reduce the associated risk of COVID-19 infection. Subjects: 220,265 American veterans supplemented with vitamin D3 (cholecalciferol or calcifediol) 34,710 supplemented with vitamin D2 (ergocalciferol or doxercalciferol) 407,860 untreated patients (control)
Dose
Dosage options included 20 IU, 40 IU, 100 IU, 125 IU, 200 IU, 250 IU, 400 IU, 500 IU, 800 IU, 1000 IU, 2000 IU, 5000 IU, 8000 IU, and 50,000 IU. Source of data: Veterans Administration Corporate Data Warehouse (CDW) electronic health records between January 1, 2019, and December 31, 2020
Duration
January 1st 2019 to December 12th 2020 (before and during the pandemic)
Results
The study found that US veterans taking a vitamin D3 supplement during the pandemic were associated with a significant 20% reduction in COVID-19 infections and a significant 33% decrease in mortality within 30-days of COVID-19 infection. Veterans taking a vitamin D2 supplement were associated with a 28% reduction in COVID-19 infections and a 25% decrease in mortality within 30-days of COVID-19 infection. Veterans receiving higher cumulative doses and higher average daily doses of vitamin D had a greater associated reduction in COVID-19 infection rates than veterans receiving lower doses. The 50,000 IU dosage may be especially beneficial. At an average daily dosage of 50,000 IU, there was a 49% associated reduction in COVID-19 infections in patients with low vitamin D levels. Based on these results, there would have been approximately 4 million fewer COVID-19 cases and 116,000 deaths avoided in 2020. These values were calculated by applying the estimated 20% average reduction in infection and 33% reduction in death after infection to a total of 19,860,000 cases and 351,999 deaths through 2020. The COVID-19 rates were 2.66% among participants treated with vitamin D3 and 3.30% among the untreated participants, The rates of COVID-19 infection followed by death within 30 days were 0.23% among participants treated with vitamin D3 and 0.35% among untreated participants. Conclusion: Vitamin D3 could be a helpful tool for reducing the spread of COVID-19 infection and related deaths, particularly as a large proportion of the UK and US population have suboptimal blood levels of vitamin D.
To explain the strength of the association between the protective role of vitamin D supplementation and the risk of death and admission to intensive care units (ICUs) in patients with COVID-19. Studies analysed: 5 randomised clinical trials that had been published before September 2022
Study Type
Meta-analysis and trial sequential analysis Authors: Leading Italian doctors and scientists
Purpose
To explain the strength of the association between the protective role of vitamin D supplementation and the risk of death and admission to intensive care units (ICUs) in patients with COVID-19. Studies analysed: 5 randomised clinical trials that had been published before September 2022
Dose
5000 IU; 10,000 IU; 21,280 IU; 21,260 IU; 200,000 IU
Results
The study found a conclusive association between vitamin D supplementation and a decreased risk of death (0.49) and ICU admission (0.28) among patients with COVID-19. This means that vitamin D was associated with 51% better protection against death and 72% better protection against ICU administration. Using "trial sequential analysis", a method used to determine if there is enough evidence to draw a conclusion or if more data is needed, the study determined that the pooled data conclusively shows a positive association between vitamin D supplementation and reduced risk of death and ICU admission in COVID-19 patients.
To determine the effects of 5000 IU versus 1000 IU of daily vitamin D3 supplementation on the recovery of symptoms among mild to moderate COVID-19 patients with sub-optimal vitamin D levels.
Study Type
Randomised clinical trial
Purpose
To determine the effects of 5000 IU versus 1000 IU of daily vitamin D3 supplementation on the recovery of symptoms among mild to moderate COVID-19 patients with sub-optimal vitamin D levels.
Dose
5000 IU or 1000 IU of vitamin D. The study used 1000 IU as the control because it would be unethical to give a placebo to individuals with suboptimal vitamin D levels. 1000 IU is regarded as a standard control.
Participants
69 men and women
Duration
90 days
Results
Among patients with sub-optimal vitamin D status and mild to moderate COVID-19 symptoms, 5000 IU of daily oral vitamin D3 supplementation for 2 weeks was associated with a significantly shorter time to recovery for coughs and loss of taste. 5000 IU of vitamin D resulted in a significant increase in vitamin D levels in the blood, whilst 1000 IU of vitamin D did not.
To evaluate the effect of vitamin D3 treatment on intensive care unit admissions and death rates among Spanish patients hospitalised with COVID-19.
Study Type
Randomised clinical trial
Purpose
To evaluate the effect of vitamin D3 treatment on intensive care unit admissions and death rates among Spanish patients hospitalised with COVID-19.
Dose
21,280 IU (0.532 mg) of oral vitamin D3 (calcifediol) on days 1,3 and 7 and then weekly until discharge or ICU admission. The control group received no vitamin D. All patients also received standard treatments for COVID.
Participants
76 Spanish patients hospitalised with COVID-19
Duration
4 weeks
Results
Vitamin D administration was associated with significant reductions in the need for ICU treatment among patients requiring hospitalisation due to proven COVID-19. Vitamin D was also associated with reductions in the severity of COVID-19.
To evaluate the effect of vitamin D3 on the immune response against COVID-19 in individuals with severe COVID-19 symptoms.
Study Type
Randomised clinical trial (single-blind)
Purpose
To evaluate the effect of vitamin D3 on the immune response against COVID-19 in individuals with severe COVID-19 symptoms.
Dose
10.000 IU of daily vitamin D3 or a control (2000 IU of vitamin D3)
Participants
85 patients hospitalised with COVID-19
Duration
8 to 29 days
Results
Vitamin D3 administration was associated with shorter hospital stays and improvements in the inflammatory and cytotoxic response against COVID-infected cells.
To evaluate the effect of vitamin D3 treatment on COVID-19–related outcomes
Study Type
Clinical trial (non-randomised)
Purpose
To evaluate the effect of vitamin D3 treatment on COVID-19–related outcomes
Dose
21.620 IU on day 1 (532 mcg) and 10.810 IU on days 3, 7, 15, and 30 (266 mcg)
Participants
838 patients with COVID-19 Study duration: March to May 2020
Results
In patients hospitalised with COVID-19, treatment with vitamin D3 was associated with significantly reduced ICU admission and death.
Autoimmune disease
To investigate whether vitamin D and marine-derived long chain omega 3 fatty acids reduce the risk of autoimmune disease.
Study Type
Randomised clinical trial (double-blind and placebo-controlled)
Purpose
To investigate whether vitamin D and marine-derived long chain omega 3 fatty acids reduce the risk of autoimmune disease.
Dose
2000 IU (50 mcg) per day of vitamin D per day or matched placebo, 1000 mg/day omega 3 fatty acids or matched placebo.
Participants
There were 25 871 participants (12 786 men ≥ 50 years old and 13 085 women ≥ 55 years old).
Duration
~5 years
Results
Vitamin D supplementation was associated with a 22% reduction in autoimmune disease (based on a hazard ratio of 0.78). Among the participants who received vitamin D, 123 individuals developed an autoimmune disease compared to 155 individuals in the placebo group (statistically significant). Although omega 3 fatty acid supplementation was associated with a lower rate of autoimmune disease, the results were not statistically significant.
Diabetes
To evaluate whether administration of vitamin D decreases risk for diabetes among people with prediabetes. Studies analysed: 3 randomised clinical trials
Study Type
Systematic review & meta-analysis
Purpose
To evaluate whether administration of vitamin D decreases risk for diabetes among people with prediabetes. Studies analysed: 3 randomised clinical trials
Dose
20 000 IU (500 mcg) weekly; cholecalciferol, 4000 IU (100 mcg) daily; or eldecalcitol, 0.75 mcg daily, versus matching placebos.
Results
Vitamin D reduced relative risk over time for diabetes by 15% in adjusted analyses, with a 3-year absolute risk reduction of 3.3%. Among participants assigned to the vitamin D group who maintained a blood level of at least 50 ng/mL compared with 20 to 29 ng/mL, vitamin D3 supplementation was associated with a reduced relative risk over time for diabetes by 76%, with a 3-year absolute risk reduction of 18.1%. Conclusion: In adults with prediabetes, vitamin D may be effective at decreasing risk for diabetes.
Dementia
To evaluate the effects of Vitamin D on the incidence of dementia. Number of participants: 12,388 participants with average age of 71 Study duration: 10 years
Study Type
Cohort study (a group of individuals were observed over a long period of time to evaluate the effects of vitamin D supplementation)
Purpose
To evaluate the effects of Vitamin D on the incidence of dementia. Number of participants: 12,388 participants with average age of 71 Study duration: 10 years
Results
Vitamin D supplementation was associated with a 40% lower relative risk of dementia over time compared to no exposure to vitamin D. Participants taking vitamin D had less mild cognitive impairment and less depression. 2,696 of the 12,388 participants developed dementia. Among these 2,696 participants, 2,017 (74.8%) had no exposure to vitamin D. Thus, the majority of participants who developed dementia did not take any vitamin D. The researchers did not find any difference in effects between vitamin D3 and D2.
To estimate the association between vitamin D deficiency and risk of developing Alzheimer’s disease and dementia. Studies analysed: 5 observational studies
Study Type
Meta-analysis
Purpose
To estimate the association between vitamin D deficiency and risk of developing Alzheimer’s disease and dementia. Studies analysed: 5 observational studies
Results
The meta-analysis showed that subjects with deficient vitamin D status (with blood levels less than 20 ng/mL) were at increased risk of developing Alzheimer’s disease by 21% compared with those with vitamin D levels greater than 50 nmol/L. Conclusion: Deficient vitamin D status may be associated with increased risk of developing Alzheimer’s disease and dementia.
To evaluate the effects of oral vitamin D supplementation on the incidence of influenza and upper respiratory infections during the winter and early spring in patients with inflammatory bowel disease, a term used to describe a group of chronic inflammatory disorders of the gastrointestinal tract.
Study Type
Prospective, randomised, double-blind, placebo-controlled trial
Purpose
To evaluate the effects of oral vitamin D supplementation on the incidence of influenza and upper respiratory infections during the winter and early spring in patients with inflammatory bowel disease, a term used to describe a group of chronic inflammatory disorders of the gastrointestinal tract.
Dose
500 IU/day (2 x 250 IU capsules) of vitamin D supplementation or placebo
Participants
237 male and female patients who had inflammatory bowel disease, with an average age of 45 years (223 completed the study)
Duration
6 months
Results
The study found no significant difference in the incidence of influenza between the vitamin D group and the placebo group; however, researchers observed that upper respiratory tract infections were significantly less frequent in the vitamin D group (19 of 115, 16.5%) compared with the placebo group (30 of 108, 27.8%). This effect was more pronounced in patients with low 25-hydroxyvitamin D (25-OHD) levels, where the incidence of upper respiratory tract infection was significantly lower in the vitamin D group (5 of 40, 12.5%) than in the placebo group (13 of 37, 35.1%). The incidence of upper respiratory infection was 41% significantly lower in the vitamin D group (relative risk, 0.59; 95% CI, 0.35–0.98) compared to placebo group. The relative risk of upper respiratory infection in patients with low 25-OHD levels was 0.36, indicating that the risk of upper respiratory infection was 64% lower in the vitamin D group compared to the placebo group.
How They Measured It
Influenza infection was diagnosed using a influenza virus test kit. In addition, a self-reported questionnaire was used to gather information on influenza infection and upper respiratory infection, including questions about vaccination, fever, symptoms, hospital visits, and influenza testing results.
To evaluate the effects of oral vitamin D supplementation on flu and other upper respiratory infections in patients with inflammatory bowel disease (IBD), which is a group of long-term conditions that cause inflammation in the digestive tract, during winter and early spring months when these infections are more common.
Study Type
Prospective, randomised, double-blind, placebo-controlled trial
Purpose
To evaluate the effects of oral vitamin D supplementation on flu and other upper respiratory infections in patients with inflammatory bowel disease (IBD), which is a group of long-term conditions that cause inflammation in the digestive tract, during winter and early spring months when these infections are more common.
Dose
500 IU/day (2 x 250 IU capsules) of vitamin D supplementation or placebo
Participants
237 male and female patients who had inflammatory bowel disease, with an average age of 45 years (223 completed the study)
Duration
6 months
Results
The study found that taking vitamin D did not reduce the number of flu cases compared to a placebo. However, the researchers observed that participants who took vitamin D demonstrated significantly fewer upper respiratory infections (like colds) than those on the placebo. Specifically, 16.5% of the vitamin D group got these infections, compared to 27.8% in the placebo group. This benefit was even greater for those with low vitamin D levels, where only 12.5% in the vitamin D group got infections, compared to 35.1% in the placebo group. Overall, taking vitamin D reduced the risk of upper respiratory infections by 41%, and for those with low vitamin D levels, the risk was reduced by 64%.
How They Measured It
Influenza (flu) infection was diagnosed using a virus test kit. In addition, a self-reported questionnaire was used to gather information on flu and upper respiratory infection, including questions about vaccination, fever, symptoms, hospital visits, and influenza testing results.
To evaluate the effects of high-dose vitamin D3 supplementation for 12 months on the incidence and severity of acute respiratory infections in older long-term care residents.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To evaluate the effects of high-dose vitamin D3 supplementation for 12 months on the incidence and severity of acute respiratory infections in older long-term care residents.
Dose
100,000 IU/month of vitamin D3 (equivalent to 3,000–4,000 IU/day) or a standard-dose of monthly vitamin D3 as a placebo (equivalent to 400–1,000 IU/day). All trial participants received at least 400 IU per day equivalent of vitamin D to meet the Institute of Medicine Dietary Reference Intake.
Participants
107 long-term care older patients aged 60 years and older
Duration
12 months
Results
The researchers observed a significant 40% reduction in the incidence rate of acute respiratory infections in the high-dose vitamin D group compared to the standard-dose group. In the high-dose group, 17 participants (31%) experienced at least one acute respiratory infection, while in the standard-dose group, the number was 24 participants (46%). In addition, the researchers observed lower incidence of upper acute respiratory infections in the high-dose vitamin D group (13 participants, 24%) compared to the standard-dose group (20 participants, 38%). There were no differences in incidence of lower acute respiratory infection, urinary tract infection, or other infections or hospitalizations for acute respiratory infections.
How They Measured It
Upper (common colds, sinusitis, pharyngitis, otitis media) and lower (acute bronchitis, influenza, pneumonia) acute respiratory infections that required medical attention were measured using a chart review method, a research technique that involves analysing medical records and other documents related to patient care.
To evaluate the effects of high-dose vitamin D3 supplementation for 12 months on the number and severity of acute respiratory infections (like colds and pneumonia) in older people living in long-term care facilities.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To evaluate the effects of high-dose vitamin D3 supplementation for 12 months on the number and severity of acute respiratory infections (like colds and pneumonia) in older people living in long-term care facilities.
Dose
100,000 IU/month of vitamin D3 (equivalent to 3,000–4,000 IU/day) or a standard-dose of monthly vitamin D3 as a placebo (equivalent to 400–1,000 IU/day). All trial participants received at least 400 IU per day equivalent of vitamin D to meet the Institute of Medicine Dietary Reference Intake.
Participants
107 long-term care older patients aged 60 years and older
Duration
12 months
Results
The study found that older people in long-term care who took high doses of vitamin D had 40% fewer acute respiratory infections compared to those who took standard doses. In the high-dose group, 31% had at least one infection, while 46% in the standard-dose group did. Additionally, fewer people in the high-dose group had upper respiratory infections (24%) compared to the standard-dose group (38%). There were no differences between the groups in lower respiratory infections, urinary tract infections, other infections, or hospitalizations due to respiratory infections.
How They Measured It
Upper (common colds, sinusitis, pharyngitis, otitis media) and lower (acute bronchitis, influenza, pneumonia) acute respiratory infections that required medical attention were measured using a chart review method, a research technique that involves analysing medical records and other documents related to patient care.
To assess the effects of vitamin D3 supplementation versus placebo, and of gargling versus no-gargling in university students with an upper respiratory tract infection, a common type of infection that affects the nose, throat, and sinuses.
Study Type
Randomised controlled trial
Purpose
To assess the effects of vitamin D3 supplementation versus placebo, and of gargling versus no-gargling in university students with an upper respiratory tract infection, a common type of infection that affects the nose, throat, and sinuses.
Dose
Group 1: 10,000 IU/week as a single dose of vitamin D3 and gargling intervention (to gargle with approximately 30 mL of tap water for 30 seconds twice daily) Group 2: Placebo and gargling Group 3: 10,000 IU/week as a single dose of vitamin D3 and no gargling Group 4: Placebo and no gargling
Participants
600 male and female participants aged 18-21 years (492 were included in complete case analysis)
Duration
2 months
Results
Fewer participants reported clinical upper respiratory tract infections in the vitamin D3 group (27%) than those in the placebo group (34%). Although this difference was not significant, the study found an association between weekly supplementation with vitamin D and a statistically significant 46% lower relative risk for laboratory confirmed upper respiratory tract infections compared to placebo. The researchers also observed a lower risk of upper respiratory tract infection and a lower mean viral load in participants receiving vitamin D3 compared to those receiving placebo. A lower average viral load means there is a reduced amount of virus present in the nasal swabs collected from the infected study participants. However, the reduction in clinical upper respiratory tract infection after vitamin D3 supplementation was not statistically significant when compared to placebo. Gargling did not show a statistically significant reduction in laboratory confirmed upper respiratory tract infection. Average symptom severity appeared to be greater in the vitamin D3 group for both clinical and laboratory confirmed upper respiratory tract infection. However the difference was also not statistically significant.
To assess the effects of vitamin D3 supplementation versus placebo, and of gargling versus no-gargling in university students with an upper respiratory tract infection, a common type of infection that affects the nose, throat, and sinuses (e.g. colds).
Study Type
Randomised controlled trial
Purpose
To assess the effects of vitamin D3 supplementation versus placebo, and of gargling versus no-gargling in university students with an upper respiratory tract infection, a common type of infection that affects the nose, throat, and sinuses (e.g. colds).
Dose
Group 1: 10,000 IU/week as a single dose of vitamin D3 and gargling intervention (to gargle with approximately 30 mL of tap water for 30 seconds twice daily) Group 2: Placebo and gargling Group 3: 10,000 IU/week as a single dose of vitamin D3 and no gargling Group 4: Placebo and no gargling
Participants
600 male and female participants aged 18-21 years (492 were included in complete case analysis)
Duration
2 months
Results
The study found that fewer people in the vitamin D3 group (27%) reported having upper respiratory infections compared to the placebo group (34%), but this difference wasn't significant. However, taking vitamin D3 weekly was associated with a significant 46% lower risk of laboratory-confirmed upper respiratory infections (infections verified through specific lab tests) compared to the placebo. Moreover, the researchers observed that gargling didn't significantly reduce the number of laboratory-confirmed infections. T
To determine the effects of vitamin D supplementation on the number of absences from duty due to acute respiratory tract infection in young men.
Study Type
Randomised, double-blind, controlled trial
Purpose
To determine the effects of vitamin D supplementation on the number of absences from duty due to acute respiratory tract infection in young men.
Dose
400 IU/day of vitamin D3 or placebo
Participants
164 Finnish men who were undergoing compulsory periodic military training, aged 18-28 years
Duration
6 months
Results
The researchers observed significantly higher average serum 25(OH)D concentrations in the vitamin D3 group (71.6 nmol/L) compared to the placebo group (51.3 nmol/L). The number of days absent from duty due to respiratory tract infection did not differ between groups. Nevertheless, the proportion of men who remained healthy throughout the 6-month study period was significantly greater in the intervention group (41 of 80 [51.3%] ) than in the placebo group (30 of 80 [35.7%] ). Self-reported symptoms such as cough, runny nose, sore throat, fever, and common cold symptoms did not differ significantly between the intervention and placebo groups.
To determine the effects of vitamin D supplementation on the number of absences from work due to acute respiratory tract infection (like colds or the flu) in young men.
Study Type
Randomised, double-blind, controlled trial
Purpose
To determine the effects of vitamin D supplementation on the number of absences from work due to acute respiratory tract infection (like colds or the flu) in young men.
Dose
400 IU/day of vitamin D3 or placebo
Participants
164 Finnish men who were undergoing compulsory periodic military training, aged 18-28 years
Duration
6 months
Results
The researchers observed that men taking vitamin D3 had a significantly higher average vitamin D levels compared to those taking a placebo. However, the number of days they missed work due to respiratory infections was the same for both groups. Despite this, more men in the vitamin D3 group (51.3%) stayed healthy throughout the 6-month study compared to the placebo group (35.7%). On the other hand, symptoms like cough, runny nose, sore throat, fever, and common cold did not differ significantly between both groups.
To investigate the effects of vitamin D supplementation on infectious symptoms and antibiotic consumption among patients with antibody deficiency or frequent respiratory tract infections.
Study Type
Randomised, double-blind placebo-controlled trial
Purpose
To investigate the effects of vitamin D supplementation on infectious symptoms and antibiotic consumption among patients with antibody deficiency or frequent respiratory tract infections.
Dose
4000 IU/day of vitamin D3 supplementation or placebo oil
Participants
140 men and women who were susceptible to respiratory tract infections and with an average age of 55 (Vitamin D group) and 51 years (placebo) (124 participants completed the study)
Duration
1 year
Results
The study found an association between one year of vitamin D3 intake and significant improvement in questionnaire scores related to respiratory tract infections compared to the placebo group. The researchers also observed a significant 63.5% reduction in the odds of antibiotic use among patients with frequent respiratory tract infections. Specifically, the absolute values indicated 33 days on antibiotics for the placebo group and 16 days for the vitamin D3 group, signifying a reduction of 17 days in the vitamin D3 group. Moreover, the vitamin D group had a significantly higher level of 25-hydroxyvitamin D3, a marker of vitamin D status, compared to placebo (133.4 vs 66.6 nmol/l). There was a trend towards more frequent reports of adverse events in the placebo group compared to the vitamin D group.
How They Measured It
Respiratory tract infections were assessed using a daily questionnaire which measured various parameters including symptoms related to the respiratory tract, ears and sinuses, malaise and use of antibiotics.
To investigate the effects of vitamin D supplementation on infectious symptoms and antibiotic consumption among patients with frequent respiratory tract infections.
Study Type
Randomised, double-blind placebo-controlled trial
Purpose
To investigate the effects of vitamin D supplementation on infectious symptoms and antibiotic consumption among patients with frequent respiratory tract infections.
Dose
4000 IU/day of vitamin D3 supplementation or placebo oil
Participants
140 men and women who were vulnerable to respiratory tract infections and with an average age of 55 (Vitamin D group) and 51 years (placebo) (124 participants completed the study)
Duration
1 year
Results
The study found an association between one year of vitamin D3 intake and significant improvement in questionnaire scores related to respiratory tract infections compared to the placebo group. The researchers observed that patients with frequent respiratory infections who took vitamin D had a significantly 63.5% lower chance of needing antibiotics. On average, the placebo group used antibiotics for 33 days, while the vitamin D group used them for only 16 days, a reduction of 17 days. The vitamin D group also had significantly higher levels of 25-hydroxyvitamin D3, which indicates better vitamin D status. Additionally, there was a tendency for more side effects to be reported in the placebo group compared to the vitamin D group.
How They Measured It
Respiratory tract infections were assessed using a daily questionnaire which measured symptoms related to the respiratory tract, ears and sinuses, malaise and use of antibiotics.
To examine the effects of vitamin D3 supplementation on salivary immune functions and symptoms of upper respiratory tract infections in vitamin D-insufficient taekwondo athletes.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To examine the effects of vitamin D3 supplementation on salivary immune functions and symptoms of upper respiratory tract infections in vitamin D-insufficient taekwondo athletes.
Dose
5000 IU/day of vitamin D3 or placebo
Participants
25 male taekwondo athletes aged 19-22 years
Duration
4 weeks during winter training
Results
The researchers observed a significant increase in serum 25(OH)D concentration from 29 nmol/L (deficient) to 100 nmol/L (normal) in taekwondo athletes after 4 weeks of vitamin D supplementation, while there no significant changes were observed in the placebo group. Serum 25(OH)D is a measure of the concentration of 25-hydroxyvitamin D in the blood, providing an assessment of an individual's vitamin D status The participants in the vitamin D group reported lower upper respiratory tract infection symptoms (i.e., runny nose, sneezing, cough) and total upper respiratory tract infection symptoms compared to the participants in the placebo group. In addition, The change in serum 25(OH)D concentration was negatively associated with total upper respiratory tract infection symptoms. This means that the higher levels of serum 25(OH)D concentration, the lower total upper respiratory tract infection symptoms were reported. Overall, the findings suggest a potential link between vitamin D supplementation, increased serum 25(OH)D levels, and a reduction in upper respiratory tract infection symptoms among taekwondo athletes.
How They Measured It
Upper respiratory tract infections were assessed using a self-reported questionnaire called the “Wisconsin Upper Respiratory Symptom Survey-11“, which measures symptoms and severity of upper respiratory tract infection symptoms.
To examine the effects of vitamin D3 supplementation on immune function and symptoms of upper respiratory infections (like colds) in taekwondo athletes who don't have enough vitamin D.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To examine the effects of vitamin D3 supplementation on immune function and symptoms of upper respiratory infections (like colds) in taekwondo athletes who don't have enough vitamin D.
Dose
5000 IU/day of vitamin D3 or placebo
Participants
25 male taekwondo athletes aged 19-22 years
Duration
4 weeks during winter training
Results
The researchers observed that taekwondo athletes who took vitamin D supplements demonstrated a significant increase in their average vitamin D levels from 29 nmol/L (deficient) to 100 nmol/L (normal) after 4 weeks, while those in the placebo group had no significant changes. The participants in the vitamin D group reported fewer symptoms of upper respiratory infections, like runny nose, sneezing, and cough. Overall, the findings suggest that vitamin D supplements may help boost vitamin D levels and reduce symptoms of upper respiratory infections in taekwondo athletes.
How They Measured It
Upper respiratory tract infections were assessed using a self-reported questionnaire, which measures symptoms and severity of upper respiratory tract infection symptoms.
To investigate the effects of vitamin D3 on the number of symptoms and incidents when an upper respiratory tract infection (like a cold) starts and how often people use medication like antibiotics and fever reducers.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To investigate the effects of vitamin D3 on the number of symptoms and incidents when an upper respiratory tract infection (like a cold) starts and how often people use medication like antibiotics and fever reducers.
Dose
10 µg/day of vitamin D3 or placebo
Participants
215 Japanese men and women who had insufficient or deficient blood levels of 25-hydroxyvitamin D with an average age of 53 years
Duration
16 weeks
Results
The study found an association between a daily intake of 10 µg of 25-hydroxyvitamin D3 and reduced symptoms of various upper respiratory tract infections, including runny nose, sneezing, and head congestion, compared to the placebo group. These results indicate that reduced symptoms of various upper respiratory intake may alleviate the symptoms of upper respiratory tract infections in general and nasal symptoms in particular. Additionally, the researchers observed significantly improved quality of life scores in all parameters, except for the item 'breathe easily,' in the 25-hydroxyvitamin D3 group compared to the placebo group. There was no significant difference in the number of upper respiratory tract infection events or the proportion of medication use between the 25-hydroxyvitamin D3 and placebo groups.
How They Measured It
Upper respiratory tract infections were assessed using, a self-reported questionnaire which measures symptoms and severity of upper respiratory tract infection symptoms.
To investigate the effects of vitamin D3 on the number of symptoms and incidents when an upper respiratory tract infection (like a cold) starts and how often people use medication like antibiotics and fever reducers.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To investigate the effects of vitamin D3 on the number of symptoms and incidents when an upper respiratory tract infection (like a cold) starts and how often people use medication like antibiotics and fever reducers.
Dose
10 µg/day of vitamin D3 or placebo
Participants
215 Japanese men and women who had insufficient or deficient blood levels of 25-hydroxyvitamin D with an average age of 53 years
Duration
16 weeks
Results
The study found an association between a daily intake of 10 µg of vitamin D3 and reduced symptoms of upper respiratory tract infections, including runny nose, sneezing, and head congestion, compared to the placebo group. These results indicate that reduced symptoms of various upper respiratory intake may alleviate the symptoms of upper respiratory tract infections in general and nasal symptoms in particular. Additionally, people who took 25-hydroxyvitamin D3 reported a better quality of life in most areas, except for "breathing easily." However, there was no difference between the two groups in the number of infection events or the use of medications like antibiotics and fever reducers.
How They Measured It
Upper respiratory tract infections were assessed using a self-reported questionnaire which measures symptoms and severity of upper respiratory tract infection symptoms.
To investigate the effect of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To investigate the effect of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes
Dose
5000 IU/day of vitamin D3 or placebo
Participants
50 healthy men with an average age of 20 years (39 completed the study)
Duration
14 weeks
Results
The researchers observed that the total amount of vitamin D in the blood significantly increased by 130% in the vitamin D3 group and significantly decreased by 43% in the placebo group. Additionally, the percentage change in blood cathelicidin concentration was found to be higher in the vitamin D3 group compared to the placebo group. Cathelicidin is an antimicrobial peptide produced by immune cells and elevated levels could signal an activated immune system, responding to various stimuli, including infection. Furthermore, resting SIgA (a type of antibody) secretion rates increased over time in the vitamin D3 group, but not in the placebo group. SIgA plays a crucial role in immune defence in the respiratory and digestive tracts. The increased secretion rates of SIgA and cathelicidin in the vitamin D3 group suggest that vitamin D3 supplementation may enhance athletes' immune defence mechanisms against respiratory infections. This is particularly relevant during a winter training period when athletes are more susceptible to respiratory infections due to increased exposure to cold and dry air, as well as close contact with other athletes who may be carriers of infectious agents.
To investigate the effect of vitamin D3 supplementation on the body's natural defences against infections in athletes.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To investigate the effect of vitamin D3 supplementation on the body's natural defences against infections in athletes.
Dose
5000 IU/day of vitamin D3 or placebo
Participants
50 healthy men with an average age of 20 years (39 completed the study)
Duration
14 weeks
Results
The researchers observed that athletes who took vitamin D3 supplements had a 130% significant increase in their blood vitamin D levels, while those on a placebo only had a 43% decrease. The vitamin D3 group also showed significantly higher levels of cathelicidin, a natural infection-fighting protein produced by immune cells, indicating a stronger immune response. Additionally, the vitamin D3 group had an increase in SIgA, an important antibody for defending against infections in the respiratory and digestive tracts. This boost in SIgA and cathelicidin suggests that vitamin D3 supplements can enhance the immune system in athletes, especially during winter training when they are more likely to get respiratory infections due to cold weather and close
This study aimed to determine the relationship between vitamin D status and upper respiratory tract infection of physically active men and women in military training across seasons
Study Type
Prospective cohort study
Purpose
This study aimed to determine the relationship between vitamin D status and upper respiratory tract infection of physically active men and women in military training across seasons
Participants
1644 men and women with an average age of 21 years
Duration
12 weeks
Results
The researchers observed that participants with sufficient levels of vitamin D (>50 nmol/L serum 25(OH)D) at the start of the study were 40% less likely to experience a physician-diagnosed upper respiratory tract infection during the 12 weeks of training compared to participants with serum 25(OH)D <50 nmol/L (6% vs 9%, respectively) at the start of the study. The association between initial vitamin D status and upper respiratory tract infection was more pronounced in the initial 3 weeks, during which approximately half of all upper respiratory tract infection episodes occurred. Participants with adequate 25(OH)D were only half as likely to experience an upper respiratory tract infection during this training period.
How They Measured It
Baseline measures were collected from each participant during the initial medical assessment, including a venous blood sample for the determination of serum 25(OH)D, height, body mass, ethnicity, and smoking history by self-reported questionnaire. Medical records were accessed to obtain physician-diagnosed upper respiratory tract infection and lost training days due to upper respiratory tract infection. Upper respiratory tract infection was diagnosed by a single general practice-trained physician.
To determine the relationship between vitamin D status and upper respiratory tract infections (like colds) of physically active men and women in military training across seasons
Study Type
Prospective cohort study
Purpose
To determine the relationship between vitamin D status and upper respiratory tract infections (like colds) of physically active men and women in military training across seasons
Participants
1644 men and women with an average age of 21 years
Duration
12 weeks
Results
The study found that participants with enough vitamin D (more than 50 nmol/L) at the start of the study were 40% less likely to get a doctor-diagnosed upper respiratory infection during the 12-week training period compared to those with lower vitamin D levels. This link was especially strong in the first three weeks, when about half of all infections occurred. During this period, participants with adequate vitamin D levels were only half as likely to get an upper respiratory infection.
How They Measured It
Medical records were accessed to obtain physician-diagnosed upper respiratory tract infection and lost training days due to upper respiratory tract infection. Upper respiratory tract infection was diagnosed by a single general practice-trained physician.
To compare the effects of simulated sunlight and oral D3 supplementation in winter on upper respiratory tract infection and mucosal immunity, the specialised branch of the immune system that defends mucous membrane-lined surfaces, such as the respiratory and gastrointestinal tracts. Previous studies have shown that only a few athletes and military personnel are vitamin D sufficient during the winter when skin exposure to sunlight is minimal.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To compare the effects of simulated sunlight and oral D3 supplementation in winter on upper respiratory tract infection and mucosal immunity, the specialised branch of the immune system that defends mucous membrane-lined surfaces, such as the respiratory and gastrointestinal tracts. Previous studies have shown that only a few athletes and military personnel are vitamin D sufficient during the winter when skin exposure to sunlight is minimal.
Dose
Group 1: 1000 IU/day of oral vitamin D3 supplementation (restoration phase) and 400 IU/day of vitamin D3 (maintenance phase) Group 2: oral placebo supplementation Group 3: solar simulated radiation/simulated sunlight (use of artificial light sources to mimic the effects of sunlight on the body) Group 4: solar simulated radiation placebo
Participants
250 men undertaking military training with an average age of 22 years
Duration
12 weeks
Results
Participants in both simulated sunlight and oral vitamin D supplementation groups achieved higher vitamin D levels during winter compared to their respective placebo groups. The researchers observed significant reductions in the upper respiratory tract infection burden in the after vitamin D supplementation compared to placebo, where participants had a trend of 15% reduction in the severity of peak upper respiratory tract infection symptoms and a significant 36% fewer total days with upper respiratory tract infection during military training. These reductions were similar with both simulated sunlight and oral vitamin D supplementation. Among participants with low levels of vitamin D (<50 nmol/L) at the start of the study, there was a significant 33% shorter average upper respiratory tract infection duration, a 21% lower peak upper respiratory tract infection severity, and a significant 43% fewer total days with upper respiratory tract infection when receiving vitamin D rather than placebo supplementation. There was no difference in upper respiratory tract infection prevalence and duration of upper respiratory tract infection between the vitamin D supplementation and placebo groups. The study also found that vitamin D supplementation did not influence the innate mucosal antimicrobial proteins SIgA (a type of antibody) and cathelicidin (an antimicrobial peptide), which form an important part of the first line of defence against upper respiratory infection. These findings suggest that vitamin D supplementation may reduce the burden of upper respiratory tract infections rather than prevent them.
How They Measured It
Upper respiratory tract infection was monitored by a self-reported questionnaire which measured the severity, duration, and prevalence of upper respiratory tract infection.
To compare the effects of simulated sunlight and oral D3 supplements on upper respiratory infections and mucosal immunity (the immune system that protects the surfaces of the respiratory and digestive tracts) during winter. Previous studies have shown that very few athletes and military personnel have enough vitamin D in the winter when there's little sunlight exposure.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To compare the effects of simulated sunlight and oral D3 supplements on upper respiratory infections and mucosal immunity (the immune system that protects the surfaces of the respiratory and digestive tracts) during winter. Previous studies have shown that very few athletes and military personnel have enough vitamin D in the winter when there's little sunlight exposure.
Dose
Group 1: 1000 IU/day of oral vitamin D3 supplementation (restoration phase) and 400 IU/day of vitamin D3 (maintenance phase) Group 2: oral placebo supplementation Group 3: solar simulated radiation/simulated sunlight (use of artificial light sources to mimic the effects of sunlight on the body) Group 4: solar simulated radiation placebo
Participants
250 men undertaking military training with an average age of 22 years
Duration
12 weeks
Results
Participants in both simulated sunlight and oral vitamin D supplementation groups achieved higher vitamin D levels during winter compared to their respective placebo groups. Specifically, the researchers observed significant reductions in upper respiratory tract infection burden after vitamin D supplementation compared to placebo. Participants had a trend of 15% reduction in the severity of peak symptoms and a significant 36% fewer total days with upper respiratory infections during military training. These benefits were similar with both simulated sunlight and oral vitamin D supplements. For participants with low vitamin D levels at the start of the study, there was a significant 33% shorter average infection duration, 21% milder peak symptoms, and 43% fewer total days with infections when taking vitamin D compared to placebo. However, there was no difference in the overall number of infections or their duration between the vitamin D and placebo groups.The study also found that vitamin D supplementation did not significantly affect important immune proteins, which are part of the body's first line of defence against infections. These findings suggest that vitamin D supplementation may reduce the severity and duration of upper respiratory tract infections rather than prevent them.
How They Measured It
Upper respiratory tract infection was monitored by a self-reported questionnaire which measured the severity, duration, and prevalence of upper respiratory tract infection.
To evaluate the effects of vitamin D3 on sperm parameters in infertile men with asthenozoospermia, a condition where there is a reduced motility or movement of sperm.
Study Type
Randomised, triple blind, placebo-controlled clinical trial
Purpose
To evaluate the effects of vitamin D3 on sperm parameters in infertile men with asthenozoospermia, a condition where there is a reduced motility or movement of sperm.
Dose
4000 IU/day of vitamin D3 or placebo
Participants
86 asthenozoospermic infertile men with an average age of 34 years (placebo group) and 35 years (vitamin D3 group)
Duration
3 months
Results
The study found an association between 4000 IU/day of vitamin D3 supplementation for 3 months and a significant increase in serum 25-hydroxyvitamin D3 from 18.30 ± 6.87 ng/ml at the start of the study to 32.30 ± 6.39 ng/ml at the end of the study. 25-hydroxyvitamin D3 serves as an important marker of vitamin D status, and increased levels typically indicate higher levels of vitamin D in the body, essential for various physiological processes, including bone health and immune function. In contrast, the placebo group exhibited a decrease in serum 25-hydroxyvitamin D3 from 19.17 ± 6.42 ng/ml at the start of the study to 18.93 ± 7.00 ng/ml at the end of the study. The researchers also noted a significant increase in the testosterone-to-luteinizing hormone (T/LH) ratio, a marker of testosterone production in the body, from 1.22 ± 1.48 at the start of the study to 1.32 ± 1.58 following 12 weeks of vitamin D3 supplementation, with no significant changes observed in the placebo group. An increase in the T/LH ratio may suggest that the intervention has influenced testosterone production or the hormonal balance in some way. Moreover, the study found an association between vitamin D3 supplementation and a significant increase in both total and progressive sperm motility in comparison to the placebo group. This is an important factor in male fertility, as it relates to the ability of sperm to move effectively towards the egg for fertilisation. Overall, the findings of the study suggest that vitamin D3 may have a positive effect on testosterone levels, vitamin D status, and sperm motility.
To evaluate the effects of vitamin D3 on sperm parameters in infertile men with asthenozoospermia, a condition where there is a reduced movement of sperm.
Study Type
Randomised, triple blind, placebo-controlled clinical trial
Purpose
To evaluate the effects of vitamin D3 on sperm parameters in infertile men with asthenozoospermia, a condition where there is a reduced movement of sperm.
Dose
4000 IU/day of vitamin D3 or placebo
Participants
86 asthenozoospermic infertile men with an average age of 34 years (placebo group) and 35 years (vitamin D3 group)
Duration
3 months
Results
The study found an association between taking 4000 IU of vitamin D3 daily for 3 months and significantly increased vitamin D levels in the blood from 18.30 to 32.30 ng/ml. In contrast, those who took a placebo saw a slight decrease in their vitamin D levels. The researchers also observed that vitamin D3 supplementation significantly increased the testosterone-to-luteinizing hormone ratio, which suggests an improvement in testosterone production. The placebo group did not experience any significant changes. Moreover, the study found an association between vitamin D3 supplementation and a significant increase in sperm movement (motility) in comparison to the placebo group. This is an important factor in male fertility, as it relates to the ability of sperm to move effectively towards the egg for fertilisation. Overall, the findings of the study suggest that vitamin D3 may have a positive effect on testosterone levels, vitamin D status, and sperm movement.
To evaluate the influence of Vitamin D supplementation on testosterone levels in men.
Study Type
Secondary analysis of a randomised controlled trial
Purpose
To evaluate the influence of Vitamin D supplementation on testosterone levels in men.
Dose
83 μg/day (3,332 IU/day) of vitamin D or placebo
Participants
54 nondiabetic overweight men with vitamin D deficiency and lower testosterone levels with an average age of 49 years
Duration
12 months
Results
The study found an association between one year of daily 83 μg vitamin D supplementation and a significant increase in circulating 25-hydroxyvitamin D concentrations, a marker of vitamin D status, from 32.5 ± 20.0 nmol/l at the start of the study to 86.4 ± 68.8 nmol/l at the end of the study. The researchers also observed a significant increase in total testosterone (from 10.7 ± 3.9 nmol/L to 13.4 ± 4.7 nmol/L), bioactive testosterone (from 5.21 ± 1.87 nmol/L to 6.25 ± 2.01 nmol/L), and free testosterone (from 0.22 ± 0.080 nmol/L to 0.27 ± 0.087 nmol/L)after one year of vitamin D supplementation. Bioactive testosterone and free testosterone are used to describe different forms of testosterone in the bloodstream, specifically focusing on the portion of testosterone that is readily available for use by the body's tissues and cells. In the placebo group, the 25-hydroxyvitamin D3 concentrations remained almost constant (from 29.7 ± 23.7 to 35.5 ± 8.1 nmol/l) and no significant changes were observed in any testosterone measure in the placebo group. Low levels of 25-hydroxyvitamin D3 are reported to be associated with a range of health problems, including bone disorders, cardiovascular disease, and cancer. The results of this study suggest that vitamin D supplementation was effective in raising vitamin D levels in the body and may have the potential to increase testosterone levels in men.
To evaluate the effects of Vitamin D supplementation on testosterone levels in men.
Study Type
Secondary analysis of a randomised controlled trial
Purpose
To evaluate the effects of Vitamin D supplementation on testosterone levels in men.
Dose
83 μg/day (3,332 IU/day) of vitamin D or placebo
Participants
54 nondiabetic overweight men with vitamin D deficiency and lower testosterone levels with an average age of 49 years
Duration
12 months
Results
The researchers observed that taking 83 micrograms of vitamin D daily for a year significantly increased vitamin D levels in the blood from 32.5 to 86.4 nmol/l. In contrast, the vitamin D levels remained almost the same throughout the duration of the study. The researchers also observed that vitamin D supplementation significantly increased total testosterone, bioactive testosterone, and free testosterone levels. These forms of testosterone are important for the body's tissues and cells. The placebo group, on the other hand, did not see any significant changes in testosterone levels. Overall, this study suggests that vitamin D supplements may effectively raise vitamin D levels and may also boost testosterone levels in men.
To differentiate the effects of natural sun exposure and a high dose of vitamin D3 supplementation in professional soccer players.
Study Type
Randomised placebo-controlled clinical trial
Purpose
To differentiate the effects of natural sun exposure and a high dose of vitamin D3 supplementation in professional soccer players.
Dose
6000 IU/day of vitamin D3 or placebo
Participants
28 male professional soccer players
Duration
9 months (6 weeks of vitamin D3 supplementation)
Results
During the middle of winter, almost half of the soccer players exhibited serum deficiency in 25-hydroxyvitamin D. However, after ten days of sun exposure and six weeks of vitamin D supplementation, the researchers observed a significant increase in the concentration of 25-hydroxyvitamin D, as well as improved testosterone levels (from 22.95 ± 6.4 nmol/L to 28.25 ± 3.2 nmol/L) compared to the levels at the start of the study. On the other hand, no significant differences in the placebo group compared to the levels at the start of the study were observed.
To differentiate the effects of natural sun exposure and a high dose of vitamin D3 supplementation in professional soccer players.
Study Type
Randomised placebo-controlled clinical trial
Purpose
To differentiate the effects of natural sun exposure and a high dose of vitamin D3 supplementation in professional soccer players.
Dose
6000 IU/day of vitamin D3 or placebo
Participants
28 male professional soccer players
Duration
9 months (6 weeks of vitamin D3 supplementation)
Results
During the middle of winter, almost half of the soccer players exhibited vitamin D deficiency. However, after ten days of sun exposure and six weeks of vitamin D supplementation, the researchers observed a significant increase in vitamin D levels as well as improved testosterone levels (from 22.95 ± 6.4 nmol/L to 28.25 ± 3.2 nmol/L) compared to the levels at the start of the study. On the other hand, no significant differences in the placebo group compared to the levels at the start of the study were observed.
To assess the effects of a high-dose vitamin D treatment in middle-aged men with vitamin D deficiency.
Study Type
Randomised clinical trial (uncontrolled)
Purpose
To assess the effects of a high-dose vitamin D treatment in middle-aged men with vitamin D deficiency.
Dose
600,000 IU/month (around 20,000 IU/day) of vitamin D2 It is important to note that once the patients’ serum vitamin D level reached 30 ng/mL, the researchers switched the dose to 600 000 IU/2 months and still monitored the patients. The target 25(OH)D serum level range was 30–80 ng/mL and if any level reached close to 80 ng/mL during the monitoring, the dose was decreased to 600 000 IU/3 months to prevent any vitamin D toxicity.
Participants
102 men with an average age of 53 years, who were vitamin D deficient
Duration
12 months
Results
The study found an association between high-dose of vitamin D2 supplementation in middle-aged men with vitamin D deficiency and significant increases in total testosterone levels (from 12.46 ± 3.30 nmol/L to 15.99 ± 1.84 nmol/L), and erectile function scores (from 13.88 ± 3.96 to 20.25 ± 3.24). The researchers also observed significant increases in serum vitamin D levels from the start of the study (15.16 ± 4.64 ng/mL) to 3 (31.90 ± 15.99 ng/mL), 6 (37.23 ± 12.42 ng/mL), 9 (44.88 ± 14.49 ng/mL) and 12 months (48.54 ± 11.62 ng/mL) of vitamin D supplementation.
To assess the effects of a high-dose vitamin D treatment in middle-aged men with vitamin D deficiency.
Study Type
Randomised clinical trial (uncontrolled)
Purpose
To assess the effects of a high-dose vitamin D treatment in middle-aged men with vitamin D deficiency.
Dose
600,000 IU/month (around 20,000 IU/day) of vitamin D2 It is important to note that once the patients’ blood vitamin D levels reached 30 ng/mL, the researchers switched the dose to 600 000 IU/2 months and still monitored the patients. The target vitamin D level range was 30–80 ng/mL and if any level reached close to 80 ng/mL during the monitoring, the dose was decreased to 600 000 IU/3 months to prevent any vitamin D toxicity.
Participants
102 men with an average age of 53 years, who were vitamin D deficient
Duration
12 months
Results
The study found an association between high doses of vitamin D2 supplements in middle-aged men with vitamin D deficiency and significant improvements in total testosterone and erectile function. Total testosterone levels significantly increased from 12.46 to 15.99 nmol/L, and erectile function scores significantly improved from 13.88 to 20.25. Additionally, the researchers observed that blood vitamin D levels rose significantly over time, starting at 15.16 ng/mL and increasing to 31.90 ng/mL at 3 months, 37.23 ng/mL at 6 months, 44.88 ng/mL at 9 months, and 48.54 ng/mL at 12 months.
To assess the effect of vitamin D on symptoms of depression in patients with ulcerative colitis, a chronic inflammatory bowel disease characterised by inflammation and ulcers in the innermost lining of the colon and rectum, leading to symptoms like diarrhoea, rectal bleeding, abdominal pain, and urgency to defecate.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To assess the effect of vitamin D on symptoms of depression in patients with ulcerative colitis, a chronic inflammatory bowel disease characterised by inflammation and ulcers in the innermost lining of the colon and rectum, leading to symptoms like diarrhoea, rectal bleeding, abdominal pain, and urgency to defecate.
Dose
1 mL single injection of 300,000 IU vitamin D3 or placebo (salt solution)
Participants
86 male and female patients with ulcerative colitis and an average age of 37
Duration
3 months
Results
In participants given a single injection of vitamin D3 (300,000 IU), the researchers observed a statistically significant reduction in the questionnaire scores from 12.8 at the start of the study to 8.5 after 3 months, corresponding to a reduction in reported symptoms of depression. Questionnaire scores in the placebo group, on the other hand, remained almost constant (from 13.9 to 13.6). The majority of the 46 patients in the vitamin D3 group reported improved symptoms of depression at the end of the study, with most reporting minimal symptoms of depression (increased from 24 patients (52.17%) at the beginning of the study to 36 patients (78.26%) at the end of the study). On the other hand, the number of patients in the placebo group reporting minimal symptoms of depression decreased from 25 patients (56.81%) at the start of the study to 23 patients (54.76%) at the end of the study. In the vitamin D group, the number of patients reporting moderate symptoms of depression increased from 3 patients to 5 patients, while the number of patients in the placebo group reporting severe symptoms of depression increased from 2 to 4 patients. These results suggest that vitamin D supplementation may be most beneficial for patients with minimal to mild symptoms of depression. (It is important to note that these figures mentioned were not stated in the paper but interpreted based on the graph below. Also, the methodology states that only 40 patients in the placebo group were included in the analysis but in the graph, there the total number of patients was 44 at the start of the study then 40 at the end of the study). Further analysis revealed that patients who started the study with sufficient serum vitamin D levels (equal to or higher than 30 ng/ml) experienced significant reductions in average depression scores, while no significant changes were observed in patients with insufficient serum vitamin D levels (less than 30 ng/ml) compared to placebo. This suggests that patients with sufficient serum vitamin D levels were more likely to benefit from vitamin D supplementation in terms of reducing their depression, indicating that higher serum vitamin D levels may be necessary for the antidepressant effect of vitamin D supplementation.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression from mild to moderate to severe to extreme. Questionnaire scores of 13, 19, and 28 correspond to mild, moderate, and severe depression, respectively.
To assess the effect of vitamin D on symptoms of depression in patients with ulcerative colitis, a chronic inflammatory bowel disease characterised by inflammation and ulcers in the colon and rectum, leading to symptoms like diarrhoea, rectal bleeding, abdominal pain, and urgency to defecate.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To assess the effect of vitamin D on symptoms of depression in patients with ulcerative colitis, a chronic inflammatory bowel disease characterised by inflammation and ulcers in the colon and rectum, leading to symptoms like diarrhoea, rectal bleeding, abdominal pain, and urgency to defecate.
Dose
1 mL single injection of 300,000 IU vitamin D3 or placebo (salt solution)
Participants
86 male and female patients with ulcerative colitis and an average age of 37
Duration
3 months
Results
The researchers observed that the participants who received a single injection of vitamin D3 (300,000 IU) demonstrated a significant decrease in depression symptoms, with their questionnaire scores dropping from 12.8 to 8.5 over 3 months. In contrast, scores in the placebo group stayed almost the same, going from 13.9 to 13.6. Most of the 46 patients in the vitamin D3 group reported improved depression symptoms by the end of the study. The number of patients with minimal symptoms increased from 24 (52.17%) to 36 (78.26%). In the placebo group, the number of patients with minimal symptoms slightly decreased from 25 (56.81%) to 23 (54.76%). The researchers also observed a small increase in the number of patients with moderate symptoms (from 3 to 5), while the placebo group had an increase in those with severe symptoms (from 2 to 4). These results suggest that vitamin D supplementation may be especially helpful for patients with minimal to mild symptoms of depression. Further analysis showed that patients who began the study with enough vitamin D in their blood (30 ng/ml or higher) had significant reductions in their depression scores. However, those with low vitamin D levels (less than 30 ng/ml) did not see significant changes compared to the placebo group. This suggests that patients with adequate vitamin D levels are more likely to benefit from vitamin D supplements for reducing depression, indicating that higher vitamin D levels may be necessary for the antidepressant effect.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression from mild to moderate to severe to extreme.
To investigate the effect of single injections of vitamin D on symptoms of depression in depressed patients with vitamin D deficiency
Study Type
Randomised controlled trial
Purpose
To investigate the effect of single injections of vitamin D on symptoms of depression in depressed patients with vitamin D deficiency
Dose
150,000 and 300,000 IU single injection of vitamin D or control (participants received no interventions)
Participants
109 men and women with an average age of 32-33 years
Duration
3 months
Results
The study found an association between the vitamin D injection and a significant decrease in the average depression questionnaire score when compared to the score at the start of the study, corresponding to a reduction in reported symptoms of depression. The highest decrease was observed in the high-dose group (300,000 IU), where the average questionnaire score reduced from 26.7 to 17.4. Following closely was the low-dose group (150,000 IU) with average test scores decreasing from 27.5 ± 8.4 to 20.6 ± 11.3. A slight but significant decrease in the control group was also observed, from 26.4 ± 5.2 to 24.3 ± 6.2. Before receiving a 300,000 IU vitamin D injection, 14 patients (35.9% of patients) were classified as relatively to severely depressed, while 25 (64.1%) had mild depression, and none were considered normal (0). However, after the vitamin 300,000 IU D injection, the number of patients in the relatively to severely depressed category significantly decreased from 14 to 3 (7.7%); and the number of patients with mild symptoms of depression increased from 25 to 26. There was a significant increase in the number of patients with normal symptoms of depression, from 0 patients to 10 patients (25.6% of patients). The group injected with 150,000 IU of vitamin D was not significantly different from the control group in terms of depression levels. No significant changes were observed in the control group. Regarding vitamin D deficiency, the researchers observed that the number of patients with vitamin D deficiencies was significantly lower in the groups that received vitamin D injections.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression from mild to moderate to severe to extreme. The classification of depression in this questionnaire is as follows: people with a score of 0 to 10 are considered normal; 11 to 16 mild depression; 17 to 20 in need of psychological consultation; 21 to 30 relatively depressed; 31 to 40 severely depressed; and 40+ very severely depressed
To investigate the effect of single injections of vitamin D on symptoms of depression in depressed patients with vitamin D deficiency.
Study Type
Randomised controlled trial
Purpose
To investigate the effect of single injections of vitamin D on symptoms of depression in depressed patients with vitamin D deficiency.
Dose
150,000 and 300,000 IU single injection of vitamin D or control (participants received no interventions)
Participants
109 men and women with an average age of 32-33 years
Duration
3 months
Results
The study found that a vitamin D injection significantly reduced symptoms of depression. The highest significant decrease in depression scores was seen in the high-dose group (300,000 IU), with scores dropping from 26.7 to 17.4. The low-dose group (150,000 IU) also saw a significant decrease, from 27.5 to 20.6. The control group had a slight reduction in scores, from 26.4 to 24.3. Before receiving the 300,000 IU vitamin D injection, 14 patients (35.9%) were classified as relatively to severely depressed, and 25 (64.1%) had mild depression, with none considered normal. After the injection, the number of severely depressed patients significantly dropped from 14 to 3 (7.7%), whilethose with mild symptoms increased slightly. Notably, there was a significant increase in the number of patients with normal symptoms of depression, from 0 patients to 10 patients (25.6% of patients). The 150,000 IU group did not show significant differences in depression levels compared to the control group, and the control group saw no significant changes. Overall, vitamin D injections reduced the number of patients with vitamin D deficiencies.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression from mild to moderate to severe to extreme.
To investigate the effect of vitamin D supplementation on treatment of depression in older adults
Study Type
Randomised controlled trial
Purpose
To investigate the effect of vitamin D supplementation on treatment of depression in older adults
Dose
50,000 U/week of vitamin D3 or placebo
Participants
78 male and female older adults aged over 60 years with moderate to severe depression
Duration
8 weeks
Results
Both groups showed a significant increase in the average 25-hydroxy vitamin D concentration, with the increase being about 4 times greater in the vitamin D group (from 22.57 ± 6.2 ng/ml to 43.48 ± 9.5 ng/ml) compared to the placebo group (from 21.2 ± 5.8 ng/ml to 25.9 ± 15.3 ng/ml). At the end of the study, the depression score significantly decreased from 9.25 to 7.48 in the vitamin D group, while there was a non-significant increase in the depression score in the placebo group. No patients in the vitamin D group showed severe depression after intervention, while 10 patients in the placebo group had severe depression. Participants in the vitamin D group who had higher depression scores before the study were more likely to experience a greater improvement in their reported symptoms of depression at the end of the study.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of depression of the elderly. The questionnaire score above 5 suggests mild to moderate depression, and score above 10 is indicating severe depression
To investigate the effect of vitamin D supplementation on depression in older adults
Study Type
Randomised controlled trial
Purpose
To investigate the effect of vitamin D supplementation on depression in older adults
Dose
50,000 U/week of vitamin D3 or placebo
Participants
78 male and female older adults aged over 60 years with moderate to severe depression
Duration
8 weeks
Results
Both groups in the study saw an increase in their vitamin D levels, but the increase was about four times greater in the vitamin D group (from 22.57 to 43.48 ng/ml) compared to the placebo group (from 21.2 to 25.9 ng/ml). By the end of the study, the depression scores in the vitamin D group significantly dropped from 9.25 to 7.48, while the placebo group saw a slight, non-significant increase in depression scores. No patients in the vitamin D group had severe depression after the intervention, whereas 10 patients in the placebo group did. Those in the vitamin D group who had higher depression scores at the start of the study experienced the most significant improvements.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of depression of the elderly.
To examine the effect of vitamin D supplementation on symptoms of depression on patients with major depressive disorder
Study Type
Randomised controlled trial
Purpose
To examine the effect of vitamin D supplementation on symptoms of depression on patients with major depressive disorder
Dose
50,000 IU/week of vitamin D or placebo
Participants
62 male and female patients who had major depressive disorder, with an average age of 42 years
Duration
3 months
Results
The vitamin D levels of the participants rose significantly by the end of the study in both male and female subjects after vitamin D supplementation, while no change was observed in the placebo group. Mildly depressed male participants showed no significant changes in their questionnaire scores after vitamin D supplementation. However, males with moderate, severe, and extreme depression showed significant decreases in their questionnaire scores after vitamin D supplementation, corresponding to a decrease in reported symptoms of depression. Female subjects diagnosed with mild depression also displayed no significant differences in their questionnaire scores after vitamin D supplementation. Women with moderate, severe, and extreme depression had significantly lower questionnaire scores after vitamin D supplementation. For female patients with moderate depression, questionnaire scores decreased from 28 ± 1.2 to 23 ± 1.4. For severe depression, questionnaire scores decreased from 36 ± 0.9 to 27 ± 3.6. For female patients with extreme depression, questionnaire scores decreased from 44 ± 1.5 to 34 ± 2.5. Blood serotonin levels, a neurotransmitter that plays a role in regulating mood, significantly increased after vitamin D supplementation in both male patients (before 330 ± 68 vs. after 534 ± 25 ng/ml) and female patients (before 278 ± 34 vs. after 483 ± 14 ng/ml). Patients who did not receive vitamin D supplementation did not display any changes in their blood serotonin levels after 3 months.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire that measures the severity of depression symptoms on a scale ranging from normal (1-10 total score) to mild (11-17), borderline clinical depression (17-21), moderate (21-31), severe (31 to 40), to extreme (over 40).
To examine the effect of vitamin D supplementation on symptoms of depression on patients with major depressive disorder
Study Type
Randomised controlled trial
Purpose
To examine the effect of vitamin D supplementation on symptoms of depression on patients with major depressive disorder
Dose
50,000 IU/week of vitamin D or placebo
Participants
62 male and female patients who had major depressive disorder, with an average age of 42 years
Duration
3 months
Results
The study found an association between vitamin D supplementation and significantly increased vitamin D levels in both men and women participants compared to their vitamin D levels at the start of the study. No significant changes were observed in the placebo group. Mildly depressed men did not show significant changes in their depression scores after vitamin D supplementation. However, men with moderate, severe, and extreme depression had significant reductions in their depression scores. Similarly, mildly depressed women did not experience significant changes, but those with moderate, severe, and extreme depression saw significant decreases in their scores. For moderately depressed women, scores dropped from 28 to 23; for severe depression, scores fell from 36 to 27; and for extreme depression, scores decreased from 44 to 34. Additionally, blood serotonin levels, which help regulate mood, significantly increased in both men (from 330 to 534 ng/ml) and women (from 278 to 483 ng/ml) after vitamin D supplementation. No changes in serotonin levels were observed in the placebo group after 3 months.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire that measures the severity of depression symptoms.
To assess the effects of a single injection of vitamin D on symptoms of depression, quality of life and clinical severity of illness in depressed patients with vitamin D deficiency.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To assess the effects of a single injection of vitamin D on symptoms of depression, quality of life and clinical severity of illness in depressed patients with vitamin D deficiency.
Dose
300,000 IU single injection of vitamin D or placebo (salt solution)
Participants
46 male and females with an average age of 36
Duration
12 weeks
Results
The study found that a single dose of 300,000 IU of vitamin D, when given in addition to normal depression treatment, was correlated with significantly improved questionnaire scores for symptoms of depression. More specifically, the scores decreased from 19.4 ±4.0 to 3.0 (2.0–4.0), whereas the scores in the placebo group decreased from 17.44 ±3.1 to 5.0 (3.2–8.0) in the placebo group.Patients injected with vitamin D also reported significantly increased quality of life, as their scores increased from 27.6 ±5.7 to 50.9 ±7.1, compared to the slight increase in the placebo group from 30.6 ±6.0 to 42.1 ±6.1. In patients with major depressive disorder and vitamin D deficiency, the clinical severity of illness/depression improved more in the vitamin D group (from 5.4 ±0.9 to (1.0–2.0) than in the placebo group (5.1 ± 0.7 to 2.0–4.0).
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the clinical severity of depression. A score of 0–7 is considered to be within normal range (or clinical remission), 8-16 mild depression; 17-23 moderate depression; and (≥24) severe depression. Quality of life was also assessed using a self-reported questionnaire. The clinical severity of illness/depression was assessed using a clinician-rated scale which measures the severity of illness, global improvement or change, and therapeutic response.
To assess the effects of a single injection of vitamin D on symptoms of depression, quality of life and severity of illness in depressed patients with vitamin D deficiency.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To assess the effects of a single injection of vitamin D on symptoms of depression, quality of life and severity of illness in depressed patients with vitamin D deficiency.
Dose
300,000 IU single injection of vitamin D or placebo (salt solution)
Participants
46 male and females with an average age of 36
Duration
12 weeks
Results
The study found that a single dose of 300,000 IU of vitamin D, given alongside regular depression treatment, was associated with significantly improved depression symptoms. Patients who received the vitamin D injection also reported a significant increase in their quality of life compared to those who received a placebo. For patients with both major depression and a vitamin D deficiency, the researchers observed that the severity of their depression significantly improved more with the vitamin D treatment than with the placebo.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the clinical severity of depression. Quality of life was also assessed using a self-reported questionnaire. The clinical severity of illness/depression was assessed using a clinician-rated scale which measures the severity of illness, global improvement or change, and therapeutic response.
To examine the effects of vitamin D without antidepressant drugs on depressive symptoms in type 2 diabetic patients with mild to moderate depressive symptoms. Previous studies have shown that diabetes increases the odds of depression and depression is often associated with poor glycemic control and complications of diabetes.
Study Type
Randomised, double-blind, placebo controlled clinical trial
Purpose
To examine the effects of vitamin D without antidepressant drugs on depressive symptoms in type 2 diabetic patients with mild to moderate depressive symptoms. Previous studies have shown that diabetes increases the odds of depression and depression is often associated with poor glycemic control and complications of diabetes.
Dose
100 µg/day (4000 IU/day) of vitamin D or placebo
Participants
66 male and female patients with type 2 diabetes and mild to moderate depressive symptoms with an average age of 50 (vitamin D group) and 51 years (placebo group)
Duration
12 weeks
Results
The researchers observed that depression severity scores decreased by 27.6% (-5.4) in the vitamin D group, representing a significantly greater reduction than the 10.8% (-1.8) decrease in the placebo group. The study also revealed a significant difference in the average increase of D serum levels after 3 months between the vitamin D group and the placebo group, with a higher increase in the vitamin D group (16.9 ± 5.9 ng/ml vs. 0.8 ± 4.3). The vitamin D group exhibited a significantly larger decrease in HbA1c (a measure of average blood sugar levels) and serum insulin levels (a hormone that helps regulate blood sugar levels) compared to the placebo group. Lower HbA1c levels are associated with a lower risk of developing diabetes complications, while lower serum insulin levels indicate improved insulin sensitivity or the ability of insulin to clear sugar from the blood. Furthermore, triglyceride levels were found to be significantly lower in the vitamin D group compared to the placebo.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire with 21 items with a 4-point scale which identifies the severity of depression.
To examine the effects of vitamin D on depressive symptoms in type 2 diabetic patients with mild to moderate depression, without using antidepressant drugs. Previous studies have shown that people with diabetes are more likely to experience depression, and depression is often linked to poor blood sugar control and complications related to diabetes.
Study Type
Randomised, double-blind, placebo controlled clinical trial
Purpose
To examine the effects of vitamin D on depressive symptoms in type 2 diabetic patients with mild to moderate depression, without using antidepressant drugs. Previous studies have shown that people with diabetes are more likely to experience depression, and depression is often linked to poor blood sugar control and complications related to diabetes.
Dose
100 µg/day (4000 IU/day) of vitamin D or placebo
Participants
66 male and female patients with type 2 diabetes and mild to moderate depressive symptoms with an average age of 50 (vitamin D group) and 51 years (placebo group)
Duration
12 weeks
Results
To examine the effects of vitamin D on depressive symptoms in type 2 diabetic patients with mild to moderate depression, the researchers found that those who took vitamin D experienced a 27.6% significant decrease in depression severity scores, compared to a 10.8% decrease in the placebo group. The study also showed that after 3 months, the vitamin D group had a significantly higher increase in vitamin D levels in their blood compared to the placebo group. Additionally, the researchers observed that the vitamin D group demonstrated a significant decrease in HbA1c (a measure of average blood sugar levels) and serum insulin levels, which means better blood sugar control and improved insulin sensitivity. They also had lower triglyceride levels, which is beneficial for heart health. These improvements suggest that vitamin D supplementation can help reduce depressive symptoms and improve blood sugar control in type 2 diabetic patients.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which identifies the severity of depression.
To investigate the effects of aerobic exercise and vitamin D supplementation on psychiatric comorbidities in men with migraine and vitamin D insufficiency
Study Type
Randomised controlled clinical trial
Purpose
To investigate the effects of aerobic exercise and vitamin D supplementation on psychiatric comorbidities in men with migraine and vitamin D insufficiency
Dose
50,000 units/week of vitamin D
Participants
48 outpatient migraineur males
Duration
8 weeks
Results
The researchers observed a significant decrease in the average depression severity scores (from 16.83 to 7.06), a significant improvement in the average sleep quality scores (from 9.16 to 4.41), and a significant increase in the average physical self-concept scores (from 23.06 to 30.16) after 8 weeks in the group receiving aerobic exercise in combination with vitamin D supplementation, as compared to the groups receiving vitamin D alone, aerobic exercise alone, and placebo. These results suggest that combining exercise with vitamin D supplements has a greater positive effect in men with migraines and low levels of vitamin D.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression from mild to moderate to severe to extreme. Each question was scored from 0 to 3, and the highest total scores indicated more severe depression symptoms. Sleep quality and physical self-concept (a component of self-concept that is related to physical fitness, body image, and self-esteem) were also assessed by two different self-reported questionnaires which measured quality of sleep (lower scores indicate better sleep quality) and physical aspects of self-concept(higher scores demonstrate higher physical self-concept. Migraines were assessed using a monthly headache diary which measures migraine attack duration during one month before and after the end of the intervention. Visual analogue scale was used to rate the pain intensity of each attack.
To investigate the effects of aerobic exercise (cardio) and vitamin D on mental health in men who suffer from migraines and have low levels of vitamin D.
Study Type
Randomised controlled clinical trial
Purpose
To investigate the effects of aerobic exercise (cardio) and vitamin D on mental health in men who suffer from migraines and have low levels of vitamin D.
Dose
50,000 units/week of vitamin D
Participants
48 outpatient migraineur males
Duration
8 weeks
Results
The researchers observed a significant decrease in the average depression severity scores, a significant improvement in the average sleep quality scores), and a significant increase in the average physical self-concept scores after 8 weeks of aerobic exercise and vitamin D supplementation, as compared to the groups receiving vitamin D alone, aerobic exercise alone, and placebo. These results suggest that combining exercise with vitamin D supplements has a greater positive effect in men with migraines and low levels of vitamin D.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression from mild to moderate to severe to extreme. Sleep quality and physical self-concept (a component of self-concept that is related to physical fitness, body image, and self-esteem) were also assessed by two different self-reported questionnaires which measured quality of sleep (lower scores indicate better sleep quality) and physical aspects of self-concept(higher scores demonstrate higher physical self-concept. Migraines were assessed using a monthly headache diary which measures migraine attack duration during one month before and after the end of the intervention. Visual analogue scale was used to rate the pain intensity of each attack.
To determine the effects of vitamin D supplementation and maintaining sufficient serum vitamin D on symptoms of depression in patients with knee osteoarthritis and vitamin D deficiency.
Study Type
Secondary analysis of a randomised, double-blind, placebo-controlled trial
Purpose
To determine the effects of vitamin D supplementation and maintaining sufficient serum vitamin D on symptoms of depression in patients with knee osteoarthritis and vitamin D deficiency.
Dose
50,000 IU/month (1.25 mg/month) of vitamin D3 or placebo
Participants
413 male and female participants with an average age of 63 years (340 completed the study)
Duration
24 months
Results
The researchers observed that symptoms of depression scores in the vitamin D supplementation group were significantly lower by 0.66 than those in the placebo group over 24 months. Additionally, participants who maintained vitamin D sufficiency over 24 months showed significantly greater improvement in symptoms of depression (0.73 lower) compared to those with vitamin D deficiency.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire designed to measure the severity of symptoms of depression. Questionnaire scores of 5 to 9, 10 to 14, 15 to 20, and >20 represent mild, moderate, moderately severe, and severe depression, respectively.
To determine the effects of vitamin D supplementation and maintaining sufficient vitamin D levels on symptoms of depression in patients with vitamin D deficiency.
Study Type
Secondary analysis of a randomised, double-blind, placebo-controlled trial
Purpose
To determine the effects of vitamin D supplementation and maintaining sufficient vitamin D levels on symptoms of depression in patients with vitamin D deficiency.
Dose
50,000 IU/month (1.25 mg/month) of vitamin D3 or placebo
Participants
413 male and female participants with an average age of 63 years (340 completed the study)
Duration
24 months
Results
The researchers observed that participants who took vitamin D supplements had lower depression scores compared to those who took a placebo over 24 months. Additionally, those who had enough vitamin D for the entire 24 months showed even greater improvement in their depression symptoms compared to those who were deficient in vitamin D.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire designed to measure the severity of symptoms of depression.
To evaluate the effects of vitamin D supplementation on serum 25(OH)D concentration, depression severity and some pro-inflammatory biomarkers in patients with mild to moderate depression. Previous evidence suggested that the increase of proinflammatory cytokines (a group of signalling proteins that play a key role in the body's immune response, particularly in the process of inflammation) affects the function of neurons and could cause depression.
Study Type
Randomised, double-blind, clinical trial
Purpose
To evaluate the effects of vitamin D supplementation on serum 25(OH)D concentration, depression severity and some pro-inflammatory biomarkers in patients with mild to moderate depression. Previous evidence suggested that the increase of proinflammatory cytokines (a group of signalling proteins that play a key role in the body's immune response, particularly in the process of inflammation) affects the function of neurons and could cause depression.
Dose
50,000 IU of vitamin D3 every 2 weeks or placebo
Participants
56 male and female patients with mild to moderate depression with an average age of 43 years
Duration
8 weeks
Results
The study found an association between 8 weeks of vitamin D3 supplementation and statistically significant changes in the intervention group compared with controls, including an increase in 25(OH)D concentration (+40.83 ± 28.57 vs. +5.14 ± 23.44 nmol/L) and a decrease in depression severity (-11.75 ± 6.40 vs. -3.61 ± 10.40). No significant differences were observed in the placebo group when compared to baseline for the various inflammatory markers measured.
How They Measured It
Assessment of depression was carried out according to the psychiatrist’s assessments through the structural clinical diagnostic interview based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM–IV) criteria, a standardised criteria for the classification and diagnosis of mental disorders. In addition, a self-reported questionnaire was administered to measure severity of symptoms of depression.
To evaluate the effects of vitamin D supplementation on blood vitamin D levels, depression severity, and certain inflammation markers in people with mild to moderate depression. Previous evidence suggested that higher levels of inflammation proteins, which play a key role in the body's immune response, can impact brain function and might lead to depression.
Study Type
Randomised, double-blind, clinical trial
Purpose
To evaluate the effects of vitamin D supplementation on blood vitamin D levels, depression severity, and certain inflammation markers in people with mild to moderate depression. Previous evidence suggested that higher levels of inflammation proteins, which play a key role in the body's immune response, can impact brain function and might lead to depression.
Dose
50,000 IU of vitamin D3 every 2 weeks or placebo
Participants
56 male and female patients with mild to moderate depression with an average age of 43 years
Duration
8 weeks
Results
The study found an association between 8 weeks of vitamin D3 supplementation and a significant increase in vitamin D levels compared to placebo. The researchers also observed a significant decrease in depression severity in patients supplemented with vitamin D3 compared to placebo. No significant changes in the inflammatory markers were observed in both groups.
How They Measured It
Depression was evaluated by a psychiatrist using a structured interview based on the DSM-IV, which is a standard guide for diagnosing mental disorders. Additionally, participants filled out a questionnaire to report the severity of their depression symptoms.
To determine the effect of vitamin D supplementation on anxiety, depression, and inflammation in diabetic women with anxiety.
Study Type
Randomised controlled clinical trial
Purpose
To determine the effect of vitamin D supplementation on anxiety, depression, and inflammation in diabetic women with anxiety.
Dose
50,000 IU of vitamin D3 fortnightly (every 2 weeks) or placebo
Participants
51 women with type 2 diabetes with an average age of 47 years
Duration
16 weeks
Results
The researchers observed a significant 2-point decrease in depression scores in the vitamin D group, from 11.88±4.84 at the start of the study (indicating moderate depression), to 9.88±3.88 after 16 weeks (indicating mild depression). Additionally, significant reductions were noted in anxiety and stress scores in the vitamin D group. No significant changes were observed in the placebo group for all measured variables.
How They Measured It
Depression, anxiety, and stress were assessed using a self-report questionnaire, which measures the severity of depression, anxiety, and stress. Cut-off points for anxiety score are 0–9, 10–13, 14–20, 21–27, and more than 28 to classify patients into normal, mild, moderate, severe, and extremely severe states of depression, respectively.
To determine the effect of vitamin D supplementation on anxiety, depression, and inflammation in diabetic women.
Study Type
Randomised controlled clinical trial
Purpose
To determine the effect of vitamin D supplementation on anxiety, depression, and inflammation in diabetic women.
Dose
50,000 IU of vitamin D3 fortnightly (every 2 weeks) or placebo
Participants
51 women with type 2 diabetes with an average age of 47 years
Duration
16 weeks
Results
The researchers observed a significant decrease in depression scores in the vitamin D group, dropping from 11.88 (moderate depression) to 9.88 (mild depression) after 16 weeks. The researchers also observed significant reductions in anxiety and stress scores in the vitamin D group. On the other hand, no significant changes were observed in the placebo group for any of the measured variables.
How They Measured It
Depression, anxiety, and stress were assessed using a self-report questionnaire, which measures the severity of depression, anxiety, and stress.
To investigate the effects of vitamin D and symptoms of depression in women during the winter.
Study Type
Pilot study (uncontrolled)
Purpose
To investigate the effects of vitamin D and symptoms of depression in women during the winter.
Dose
5,000 IU/day of vitamin D3 supplementation
Participants
6 female patients with vitamin D deficiency with an average age of 42 years
Duration
8 weeks
Results
Vitamin D supplementation was associated not only with an increase in the serum D levels by an average of 27 ng/ml but also with a decline in the BDI-II scores of an average of 10 points compared to the start of the study. Specifically, the average BDI-II score at the end of the study was 21.2 (moderate depression) from 31.8 (severe depression) at the start of the study.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression. Potential scores range from 0 to 63 with normal (0–13), mild depression (14–19), moderate depression (20–28), and severe depression (29–63) as designated.
To investigate the effects of vitamin D and symptoms of depression in women during the winter.
Study Type
Pilot study (uncontrolled)
Purpose
To investigate the effects of vitamin D and symptoms of depression in women during the winter.
Dose
5,000 IU/day of vitamin D3 supplementation
Participants
6 female patients with vitamin D deficiency with an average age of 42 years
Duration
8 weeks
Results
The researchers observed that vitamin D supplementation significantly increased vitamin D levels by an average of 27 ng/ml and lowered depression scores by an average of 10 points. At the start of the study, the average depression score was 31.8 (severe depression), which dropped to 21.2 (moderate depression) by the end of the study.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression.
To assess the effect of vitamin D supplementation on symptoms of depression.
Study Type
Randomised, double-blind, placebo-controlled clinical trial
Purpose
To assess the effect of vitamin D supplementation on symptoms of depression.
Dose
Group 1: 40.000 IU/week of vitamin D (2 x 20.000 IU capsules) Group 2: 20.000 IU/week of vitamin D and placebo Group 3: 2 placebo capsules
Participants
441 overweight men and women aged 21-70 years (334 completed the study)
Duration
1 year
Results
The researchers observed significant reductions in the average BDI scores of participants receiving 40,000 IU/week of vitamin D supplementation (from 4.5 to 3.0) and 20,000 IU/week of vitamin D supplementation (from 5.0 to 4.0). No significant differences were observed in the total BDI scores in the placebo group. Additionally, the researchers noted that subjects with deficient serum 25(OH)D levels (below 40 nmol/L) had higher median scores on the BDI total (6.0) and BDI 1-13, the cognitive-affective subscale (2.0), indicating more symptoms of depression, compared to those with serum 25(OH)D levels above 40 nmol/L (4.5 and 1.0, respectively).
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression from mild to moderate to severe to extreme. The items constituting the questionnaire have been divided into two subscales. The first, the cognitive-affective, assesses the mental aspect of depression (items 1–13). The second, the somatic-vegetative (physical symptoms and bodily functions), measures vegetative and somatic symptoms (items 14–21).
To assess the effect of vitamin D supplementation on symptoms of depression.
Study Type
Randomised, double-blind, placebo-controlled clinical trial
Purpose
To assess the effect of vitamin D supplementation on symptoms of depression.
Dose
Group 1: 40.000 IU/week of vitamin D (2 x 20.000 IU capsules) Group 2: 20.000 IU/week of vitamin D and placebo Group 3: 2 placebo capsules
Participants
441 overweight men and women aged 21-70 years (334 completed the study)
Duration
1 year
Results
The participants taking 40,000 IU and 20,000 IU per week reported significant improvements in their depressive symptoms. No significant changes were observed in the placebo group. Additionally, participants with low vitamin D levels (below 40 nmol/L) reported higher depression scores and more cognitive and emotional symptoms compared to those with higher vitamin D levels.
How They Measured It
Symptoms of depression were assessed using a self-reported questionnaire which measures the severity of symptoms of depression from mild to moderate to severe to extreme.
To evaluate whether high dose vitamin D3 supplementation has beneficial effects on symptoms of depression in dialysis patients.
Study Type
Prospective, randomised, double-blind, placebo-controlled clinical trial
Purpose
To evaluate whether high dose vitamin D3 supplementation has beneficial effects on symptoms of depression in dialysis patients.
Dose
50,000 IU/week of vitamin D3 or placebo
Participants
746 male and female dialysis patients with depression with an average age of
Duration
52 weeks
Results
The study found an association between vitamin D3 supplementation and significant improvements in average symptom of depression scores in dialysis patients with vascular depression (4.4 decrease in average scores compared to the start of the study). However, no significant effects were observed for major depressive disorders. Overall, while vitamin D supplementation may not have the potential to reduce symptoms of depression in the overall dialysis population, it may have a beneficial effect on vascular depression.
How They Measured It
Major depressive disorders and vascular depression were diagnosed according to DSM-IV (Diagnostic and Statistical Manual of Mental Disorders) criteria, a standardised set of criteria for the classification of mental disorders. Vascular depression is characterised by the onset of symptoms of depression in individuals who are over the age of 65 or by a change in the course of depression after the occurrence of vascular disease (such as strokes or small vessel disease, etc.) In addition, symptoms of depression were assessed using the Chinese version of a self-reported questionnaire, which measures the severity of depression. Structured interviews conducted by experienced psychiatrists independently determined diagnoses and severity.
To evaluate the effects of high dose vitamin D3 supplementation on symptoms of depression in dialysis patients.
Study Type
Prospective, randomised, double-blind, placebo-controlled clinical trial
Purpose
To evaluate the effects of high dose vitamin D3 supplementation on symptoms of depression in dialysis patients.
Dose
50,000 IU/week of vitamin D3 or placebo
Participants
746 male and female dialysis patients with depression with an average age of
Duration
52 weeks
Results
The study found that vitamin D3 supplements significantly improved depression symptoms in dialysis patients with vascular depression. Vascular depression is a type of depression that occurs in people over 65 or those who develop depression symptoms after vascular diseases like strokes. However, there were no significant effects on major depressive disorders. Overall, while vitamin D supplementation may not reduce depression symptoms in all dialysis patients, it may be beneficial for those with vascular depression.
How They Measured It
Major depressive disorders and vascular depression were diagnosed using the DSM-IV criteria, a standard guide for classifying mental disorders. Vascular depression occurs in people over 65 or when depression symptoms change after vascular diseases like strokes. Depression symptoms were also measured with a Chinese version of a self-reported questionnaire. Experienced psychiatrists conducted structured interviews to independently diagnose and assess the severity of depression.
Frequently Asked Questions
Common questions about Vitamin D research
There are currently 64 peer-reviewed studies on Vitamin D (Cholecalciferol (D3)), involving 12,913 total participants. Research covers COVID-19, Autoimmune disease, Diabetes and 1 more areas. The overall evidence strength is rated as Strong.
The evidence is currently rated as "Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (64 human studies), and reported outcomes.
Vitamin D has been researched for: COVID-19, Autoimmune disease, Diabetes, Dementia. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 64 out of 64 studies are human trials. Human trials carry more weight in our evidence scoring system.
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