Folate / Vitamin B9
Research reviewed: Up until 03/2026
Folate / Vitamin B9 (Folate) is a dietary supplement with 13 published peer-reviewed studies involving 4,200 participants, researched for Pregnancy & Neural Development, Cardiovascular Health, Mental Health & Mood.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Pregnancy & Neural Development
StrongCardiovascular Health
ModerateMental Health & Mood
StrongResearch 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.
Pregnancy & Neural Development
To determine whether folic acid supplementation prevents neural tube defects in high-risk pregnancies
Study Type
Randomised, controlled trial
Purpose
To determine whether folic acid supplementation prevents neural tube defects in high-risk pregnancies
Dose
4 mg/day folic acid
Participants
1817 women with prior NTD-affected pregnancy
Duration
Periconceptional period
Results
Folic acid supplementation reduced NTD recurrence risk by 72% (RR 0.28, p<0.001).
How They Measured It
Neural tube defect incidence in offspring
To evaluate updated evidence for folic acid supplementation in preventing neural tube defects
Study Type
Systematic review and evidence report
Purpose
To evaluate updated evidence for folic acid supplementation in preventing neural tube defects
Dose
0.4-4 mg/day
Participants
Multiple large cohorts and RCTs
Duration
Periconceptional to first trimester
Results
Folic acid reduced NTD risk by 46-54% in cohort studies; high evidence supports supplementation.
How They Measured It
NTD incidence, relative risk reduction
To assess folic acid supplementation effect on maternal homocysteine and placental function
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To assess folic acid supplementation effect on maternal homocysteine and placental function
Dose
5 mg/day folic acid
Participants
320 pregnant women
Duration
First and second trimester
Results
Folic acid significantly reduced homocysteine levels and improved placental function markers.
How They Measured It
Plasma homocysteine, placental function markers
To evaluate folate supplementation effect on infant neurodevelopment
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate folate supplementation effect on infant neurodevelopment
Dose
400 ug/day
Participants
280 mother-infant pairs
Duration
Periconceptional to 6 weeks postpartum
Results
Offspring of mothers taking folate scored significantly higher on cognitive development scales at 18 months.
How They Measured It
Bayley Scales of Infant Development at 18 months
Cardiovascular Health
To assess folic acid supplementation on homocysteine and cardiovascular risk markers
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To assess folic acid supplementation on homocysteine and cardiovascular risk markers
Dose
0.5 mg/day folic acid
Participants
300 adults with elevated homocysteine
Duration
12 weeks
Results
Folic acid reduced homocysteine by 25% and improved flow-mediated dilatation by 3.2% vs placebo.
How They Measured It
Plasma homocysteine, endothelial function (FMD)
To evaluate folic acid supplementation on stroke risk in hypertensive patients
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate folic acid supplementation on stroke risk in hypertensive patients
Dose
0.8 mg/day folic acid
Participants
20702 hypertensive adults
Duration
4.5 years
Results
Folic acid reduced first stroke risk by 21% vs placebo in adults with hypertension.
How They Measured It
Stroke incidence, blood pressure
To evaluate folic acid supplementation for cardiovascular disease prevention
Study Type
Systematic review and meta-analysis
Purpose
To evaluate folic acid supplementation for cardiovascular disease prevention
Dose
Various
Participants
Multiple large trials pooled
Duration
Various
Results
Folic acid reduced stroke risk by 10-15% and significantly reduced homocysteine; effects strongest in populations without grain fortification.
How They Measured It
Cardiovascular events, homocysteine levels
To assess folic acid on endothelial function in patients with coronary artery disease
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To assess folic acid on endothelial function in patients with coronary artery disease
Dose
5 mg/day folic acid
Participants
55 CAD patients
Duration
6 weeks
Results
Folic acid significantly improved endothelial function (FMD +3.1%) and reduced homocysteine.
How They Measured It
Flow-mediated dilatation (FMD)
Mental Health & Mood
To evaluate folate augmentation in patients with depression not fully responding to antidepressants
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate folate augmentation in patients with depression not fully responding to antidepressants
Dose
500 ug methylfolate/day
Participants
127 depressed patients
Duration
10 weeks
Results
Folate augmentation significantly improved depression scores vs placebo in women (p=0.005).
How They Measured It
Hamilton Depression Rating Scale (HDRS)
To assess methylfolate supplementation on depressive symptoms in adults with depression
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To assess methylfolate supplementation on depressive symptoms in adults with depression
Dose
15 mg/day L-methylfolate
Participants
148 depressed adults
Duration
30 days
Results
Significant improvement in HDRS scores with L-methylfolate vs placebo in patients with MTHFR variants.
How They Measured It
HDRS, clinical global impression
To evaluate folic acid effect on cognitive function in elderly adults
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate folic acid effect on cognitive function in elderly adults
Dose
400 ug/day folic acid
Participants
195 older adults
Duration
2 years
Results
Folic acid supplementation significantly reduced homocysteine and slowed cognitive decline vs placebo.
How They Measured It
MMSE, cognitive battery, homocysteine
To evaluate folate supplementation role in cancer prevention across multiple RCTs
Study Type
Systematic review
Purpose
To evaluate folate supplementation role in cancer prevention across multiple RCTs
Dose
Various
Participants
Multiple trials
Duration
Various
Results
Adequate folate status associated with reduced colorectal cancer risk; high-dose supplementation effects more mixed.
How They Measured It
Cancer incidence (colorectal, breast, etc.)
To assess folic acid supplementation on anaemia prevention in pregnancy
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To assess folic acid supplementation on anaemia prevention in pregnancy
Dose
400 ug/day
Participants
1000 pregnant women
Duration
Throughout pregnancy
Results
Folic acid supplementation significantly reduced maternal anaemia and megaloblastic anaemia incidence.
How They Measured It
Haemoglobin, folate status, maternal anaemia incidence
Frequently Asked Questions
Common questions about Folate / Vitamin B9 research
There are currently 13 peer-reviewed studies on Folate / Vitamin B9 (Folate), involving 4,200 total participants. Research covers Pregnancy support, Neural tube defect prevention, Cardiovascular health. The overall evidence strength is rated as Very Strong.
The evidence is currently rated as "Very Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (13 human studies), and reported outcomes.
Folate / Vitamin B9 has been researched for: Pregnancy support, Neural tube defect prevention, Cardiovascular health. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 13 out of 13 studies are human trials. Human trials carry more weight in our evidence scoring system.
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