Green Tea Extract
Research reviewed: up until 05/2023
Green Tea Extract (Camellia sinensis) is a dietary supplement with 3 published peer-reviewed studies involving 52,816 participants, researched for Obesity with metabolic syndrome, Mortality rate.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Obesity with metabolic syndrome
ModerateMortality rate
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.
Obesity with metabolic syndrome
To examine the effects of green tea extracts and beverages on body weight, fasting glucose, and lipids, and oxidative stress in obese subjects with metabolic syndrome (which is a medical term for a combination of diabetes, high blood pressure and obesity).
Study Type
Randomised, single-blind, controlled trial
Purpose
To examine the effects of green tea extracts and beverages on body weight, fasting glucose, and lipids, and oxidative stress in obese subjects with metabolic syndrome (which is a medical term for a combination of diabetes, high blood pressure and obesity).
Dose
870 mg/day of green tea capsules (2 x 435 mg capsules) or 928 mg/day of green tea beverages (4 cups x 232 mg tea bags)
Participants
35 obese males and females with metabolic syndrome and an average age of 43
Duration
8 weeks
Results
The researchers observed that the average body weight and body mass index (BMI) of obese participants in the green tea beverage and supplementation group significantly decreased after 8 weeks. A significant reduction in the biomarkers of oxidative stress (malondialdehyde and 4-hydroxynonenal) was also observed in green tea drinkers but not in the green tea supplementation group. A decrease in oxidative stress is associated with reduced risks of cardiovascular disease. The study also found that the green tea drinkers were associated with a decreasing trend in LDL-cholesterol and an increasing trend in HDL-cholesterol compared to the control groups. High levels of LDL-cholesterol, also known as “bad” cholesterol, are associated with a higher risk for heart disease and stroke. In contrast, higher levels of HDL-cholesterol is associated with a lower risk of heart disease and stroke.
Mortality rate
To investigate the associations between green tea consumption and mortality from all causes and specific causes.
Study Type
Prospective cohort study
Purpose
To investigate the associations between green tea consumption and mortality from all causes and specific causes.
Participants
40,530 participants from the Ohsaki National Health Insurance Cohort Study
Duration
11 years of follow-up for all-cause mortality and up to 7 years of follow-up for cause-specific mortality
Results
The study found an association between increased green tea consumption and lower deaths from all causes and cardiovascular disease, except cancer. The association with lower cardiovascular disease deaths was stronger than that with deaths from all causes. The association with deaths from all causes was stronger in women.
How They Measured It
The amount of green tea consumption was determined using a food frequency questionnaire. The causes of death were investigated by reviewing the death certificates filed at Ohsaki Public Health Center.
To investigate the association between green tea consumption and death from all causes, cancer, and cardiovascular disease among elderly people.
Study Type
Population-based, prospective cohort study
Purpose
To investigate the association between green tea consumption and death from all causes, cancer, and cardiovascular disease among elderly people.
Participants
12,251 men and women aged 65–84 years
Duration
6 years follow up from December 1999 to March 2006
Results
The study found that those who consumed seven or more cups of green tea per day were associated with a 55% lower risk of death from all causes and a 75% lower risk of death from cardiovascular disease when compared with those who consumed less than one cup per day. A moderate dose of green tea consumption was also associated with a lower risk of colorectal cancer mortality.
How They Measured It
The frequency of green tea consumption was determined using questionnaires. The causes of death of the deceased subjects were identified using the National Vital Statistics Database from the Ministry of Health, Labour and Welfare of Japan.
Frequently Asked Questions
Common questions about Green Tea Extract research
There are currently 3 peer-reviewed studies on Green Tea Extract (Camellia sinensis), involving 52,816 total participants. Research covers Obesity with metabolic syndrome, Mortality rate. The overall evidence strength is rated as Moderate.
The evidence is currently rated as "Moderate Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (3 human studies), and reported outcomes.
Green Tea Extract has been researched for: Obesity with metabolic syndrome, Mortality rate. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 3 out of 3 studies are human trials. Human trials carry more weight in our evidence scoring system.
