Women taking green tea extract lost 2.4 pounds (1.1 kg) over 12 weeks. Their BMI and waist size both decreased significantly. Total cholesterol dropped by over 5%. The hunger hormone (ghrelin) decreased while the beneficial adiponectin hormone increased. No significant side effects were reported.

 Randomized, double-blind, placebo-controlled trial with 102 women (BMI >27 kg/m², waist >80 cm) for 12 weeks; outcomes: body weight, BMI, waist circumference, cholesterol, ghrelin, adiponectin, insulin.

Women taking green tea extract lost 2.4 pounds (1.1 kg) over 12 weeks. Their BMI and waist size both decreased significantly. Total cholesterol dropped by over 5%. The hunger hormone (ghrelin) decreased while the beneficial adiponectin hormone increased. No significant side effects were reported.

 To measure the effects of 60 days of enhanced green tea extract on fat burning, resting calorie burn and carbohydrate metabolism in overweight/moderately obese post-menopausal women.

Double-blind, placebo-controlled RCT; 28 non-exercising overweight/moderately obese post-menopausal women received 300 mg/day enhanced green tea extract vs placebo for 60 days, low-calorie diet.

Fat burning increased by 11% compared to placebo. Resting calorie burn (how many calories you burn just sitting still) increased by 83 calories per day. Waist circumference decreased by about 1 cm. Insulin levels and insulin resistance both improved.

 To assess whether the catechins and EGCG naturally found in Green Tea Extract produce weight loss and help maintain weight after initial loss.

Across multiple studies, green tea catechins decreased body weight by an average of 2.9 pounds (1.31 kg). They also helped people maintain their weight after initial loss. The effect was bigger in people who don't normally consume a lot of caffeine.

When you look at multiple trials together, green tea catechins (especially EGCG combined with caffeine) produce small but reliable reductions in body weight. This makes them clinically useful as part of a broader weight management program.

 To assess whether the catechins and EGCG naturally found in Green Tea Extract produce weight loss and help maintain weight after initial loss.

Across multiple studies, green tea catechins decreased body weight by an average of 2.9 pounds (1.31 kg). They also helped people maintain their weight after initial loss. The effect was bigger in people who don't normally consume a lot of caffeine.

When you look at multiple trials together, green tea catechins (especially EGCG combined with caffeine) produce small but reliable reductions in body weight. This makes them clinically useful as part of a broader weight management program.

To measure the impact of 800 mg/day green tea extract on cholesterol levels in post-menopausal women with abnormal cholesterol.

Randomized controlled trial; 100 post-menopausal women received 800 mg/day GTE (two 400 mg capsules) or placebo for 4 weeks.

 Total cholesterol dropped by 18.1 mg/dL in the green tea group compared to only 5 mg/dL in placebo. Triglycerides and LDL cholesterol also decreased significantly. No major side effects were reported.

To test whether enhanced green tea extract improves metabolism and body composition in overweight/obese post-menopausal women who do not exercise.

Double-blind, placebo-controlled trial; subjects received 300 mg/day enhanced green tea extract (150 mg twice daily, ≥13% EGCG) for 60 days.

Women taking green tea extract burned more fat throughout the day. Their bodies shifted from primarily burning carbohydrates to burning fat for energy. Belly fat decreased while muscle mass was preserved. Insulin resistance improved, the beneficial hormone adiponectin increased, and norepinephrine (which helps burn fat) went up. All of these changes point to an improved metabolic profile.

To investigate the effects of decaffeinated green tea catechins (with no caffeine or theanine) on brain function, both from a single dose and from long-term use.

Double-blind, randomized, placebo-controlled trial with 47 Japanese adults aged 50–69 reporting memory concerns; 336.4 mg green tea catechins/day (216.9 mg EGCG) with minimal caffeine (2.7 mg) for single-dose tests and 12 weeks. Computerized cognitive battery (10 tests).

A single dose reduced errors on an attention test. After 12 weeks of daily use, working memory response time improved by 52 milliseconds on a challenging memory task. Visual memory accuracy also improved.

To test whether combining green tea extract with L-theanine improves thinking and memory in people with mild cognitive impairment (MCI), and to measure brain-wave changes.

Randomized, double-blind, placebo-controlled trial with 91 MCI participants (average age 57); 1,680 mg LGNC-07/day (1,440 mg GTE + 240 mg L-theanine) for 16 weeks; subset had acute EEG testing.

There was a slight overall improvement in memory recognition. In the more impaired subgroup, memory scores and performance on an attention test (Stroop test) improved significantly. Brain-wave testing (EEG) showed increased theta waves, which are a marker of mental alertness, 3 hours after taking the supplement.

To summarize the immediate cognitive effects of caffeine, L-theanine and EGCG across human studies.

Review of 49 human trials across attention, alertness, relaxation and memory tasks.

Caffeine improves sustained attention at low doses (as little as 40 mg). L-theanine reduces tension and increases calmness at doses of 200 mg or higher. When caffeine and L-theanine are combined, they reliably improve the ability to switch attention and increase alertness while reducing jitteriness. EGCG contributes to a state of "alert calmness" and supports working memory.

To assess the safety and effectiveness of green tea catechins for supporting prostate health in men with high-grade prostatic intraepithelial neoplasia (HGPIN), a high-risk condition.

12-month randomized trial (proof-of-principle) in men at high risk; green tea catechin supplementation vs control.

Only 1 out of 30 men (3%) in the green tea catechin group developed prostate cancer compared to 9 out of 30 men (30%) in the placebo group over 12 months.

To evaluate standardized green tea catechins (providing 400 mg EGCG/day) in men with HGPIN and/or ASAP for prostate cancer prevention markers and disease progression.

Randomized, double-blind, placebo-controlled trial; 97 men received standardized green tea catechins vs placebo for 12 months. Primary outcome: one-year prostate cancer rates; secondary: combined cancer+ASAP and PSA.

While raw prostate cancer numbers didn't differ significantly, in men with HGPIN (without ASAP), the combined endpoint of cancer plus ASAP decreased significantly (3 out of 26 vs 10 out of 25 in placebo). Blood PSA levels (a marker for prostate health) decreased by 0.87 ng/mL in the green tea group. The supplement was well tolerated.

To examine whether regular green tea drinking changes prostate tissue markers related to inflammation, oxidation, and whether tea compounds actually reach prostate tissue in men scheduled for prostate removal surgery.

Exploratory, open-label, phase II randomized trial; 113 men drank six cups of brewed green tea, black tea, or water daily for approximately 3–6 weeks before surgery; tissue biomarkers were assessed.

Green tea significantly reduced NFκB inflammation markers in prostate tissue and lowered urinary oxidative DNA damage. Tea compounds were detected in prostate tissue in 94% of men who drank green tea. PSA levels showed a small but significant decrease.

To test whether catechin-rich green tea extract reduces gut-derived harmful toxins circulating in the blood (endotoxin) and intestinal inflammation in people with metabolic syndrome and healthy controls.

Randomized, double-blind, placebo-controlled crossover with 40 adults (21 metabolic syndrome, 19 healthy). Participants received decaffeinated catechin-rich green tea (approximately 890 mg/day total catechins, about 400–450 mg EGCG) for 28 days vs placebo with one-month washout; low-polyphenol diet throughout.

Harmful toxins circulating in the bloodstream (endotoxin) decreased significantly. Small intestinal "leakiness" decreased, meaning the gut barrier became stronger and kept toxins out of the blood better. Stool inflammatory markers (calprotectin and myeloperoxidase) dropped by 29% and 48% respectively. Fasting blood sugar also decreased significantly. Blood levels of catechins increased, confirming the supplement was being absorbed.

To examine how green tea extract affects the composition and metabolism of gut bacteria in samples from people with metabolic syndrome.

Ex-vivo human colon model using fresh stool from 3 adults with metabolic syndrome; samples treated with green tea extract and sequenced across fermentation phases.

Beneficial bacteria like Escherichia and Klebsiella increased while potentially harmful bacteria like Bacteroides, Citrobacter and Clostridium decreased. The ratio of Firmicutes to Bacteroidetes (an important marker of metabolic health) decreased. Free fatty acids increased and multiple metabolic pathways shifted. These changes demonstrate a substantial impact on both the types of gut bacteria and what they produce.

To evaluate short-term (7-day) green tea extract effects on intestinal bacteria, whole-body metabolism and skin response to UV stress in mice, comparing whole green tea extract to individual components (EGCG, caffeine, theanine).

Controlled animal study with multiple groups; mice received green tea extract or individual components for 7 days; DNA sequencing and metabolic profiling performed.

Green tea prevented UV light from causing unhealthy shifts in gut bacteria. It increased beneficial bacteria like Bifidobacteria and Lactobacillus. Metabolites that support skin barrier health improved. UV-caused skin redness decreased. Strong connections were found between beneficial gut bacteria and improved skin health markers.

To pool together randomized clinical trials and measure the effects of green tea supplementation on cholesterol (total, LDL, HDL, triglycerides), blood pressure, blood sugar control and inflammation.

Systematic literature search and combined analyses of 55 trials (63 effect sizes) from major databases.

Green tea supplementation significantly reduced total cholesterol by 7.62 mg/dL, LDL ("bad" cholesterol) by 5.80 mg/dL, fasting blood sugar by 1.67 mg/dL, HbA1c (long-term blood sugar marker) by 0.15%, and diastolic blood pressure by 0.87 mmHg. HDL ("good" cholesterol) increased modestly by 1.85 mg/dL.

To examine EGCG effects on blood pressure and connections to metabolism and the nervous system in obese adults.

Double-blind, randomized, placebo-controlled trial with 30 obese Thai participants (BMI ≥25), EGCG 150 mg twice daily (300 mg/day; 95% purified EGCG) vs placebo for 8 weeks.

Systolic blood pressure (top number) decreased by nearly 7 mmHg (from 122.77 to 115.85 mmHg). Diastolic pressure (bottom number) dropped by nearly 5 mmHg. These improvements were linked to obesity and insulin resistance measures. HDL ("good" cholesterol) was inversely related to blood pressure changes.

To evaluate the effect of green tea on circulating inflammatory markers (TNF-α, CRP, IL-6) in metabolic syndrome and related disorders.

Systematic review and combined analysis of 15 randomized controlled trials (12 included in pooled analysis) through March 2022.

Green tea significantly reduced circulating TNF-α (a key inflammatory marker). Subgroup analyses showed CRP (another inflammatory marker) reductions in studies lasting 8 weeks or less. Treatment duration was related to changes in IL-6 levels.

To measure how green tea affects fasting blood sugar, insulin, HbA1c (long-term blood sugar marker) and insulin resistance across many trials.

Systematic review and pooled analysis of 27 trials (2,194 participants), catechin doses 80–1,344 mg/day, durations 3 weeks–12 months.

Fasting blood sugar decreased by 1.44 mg/dL across all studies combined. When looking at subgroups, dosages of 500 mg/day of catechins or higher produced larger effects. Capsules were more effective than drinking brewed tea. HbA1c and fasting insulin showed minimal or no consistent change.

To assess whether catechin-rich green tea reduces harmful gut-derived toxins (endotoxemia) and intestinal inflammation, and whether this relates to improved fasting blood sugar.

Randomized, double-blind, placebo-controlled crossover with 40 adults (metabolic syndrome + healthy), 28-day treatment with approximately 890 mg/day catechins.

Harmful toxins circulating from the gut (endotoxin) decreased. Intestinal "leakiness" decreased, meaning the gut barrier became stronger. Fasting blood sugar significantly decreased in both metabolic syndrome and healthy groups.

To determine the relationship between dosage and blood sugar outcomes across trials.

Subgroup/dose-response analyses from the pooled trials (27 trials).

Fasting blood sugar reductions were more pronounced when people took catechin doses of 500 mg/day or higher. Capsules worked better than beverages for blood sugar improvements. HbA1c changes were inconsistent across different studies.

To investigate how EGCG protects against oxidative stress-induced cell death and understand the underlying mechanisms.

Human lens cells exposed to hydrogen peroxide (H₂O₂) with or without EGCG pre-treatment; cell viability, ROS levels, mitochondrial function and survival protein expression measured.

EGCG markedly reduced the accumulation of harmful free radicals (ROS), preserved how well the cell's energy factories (mitochondria) functioned, kept cells alive, and maintained expression of proteins that help cells survive stress. This shows multi-pathway antioxidant protection.

To evaluate EGCG effects on liver injury, antioxidant enzymes, inflammation, and detoxification pathways in animal models of liver damage.

Multiple animal studies using liver-toxic agents; EGCG dosed (typically 25–50 mg/kg) for 8 weeks; liver enzymes (AST/ALT), antioxidant enzyme activities, inflammatory cytokines and histology assessed.

EGCG reduced liver damage enzymes by 2–3 times compared to toxic controls. It increased the body's total antioxidant capacity. Inflammatory markers TNF-α and IL-6 decreased. Scar tissue formation decreased by approximately 50–57%. Antioxidant enzyme activities improved and genes involved in detoxification (SIRT1, FOXO3a) were activated.

To review human and laboratory evidence for green tea polyphenols (EGCG) on skin aging, wrinkles, hydration and dark spots.

Systematic review of studies Jan 2013–Dec 2023: 21 articles including human RCTs and lab studies assessing topical and oral green tea interventions.

Human trials showed wrinkle improvement ranging from 36.3% to 63.6% depending on the extract type. Skin darkening was reduced after 6 weeks of use. Trans-epidermal water loss (a measure of skin barrier function and hydration) improved from 9 to 7 g/m²/hr, meaning skin retained moisture better. EGCG works by neutralizing free radicals and inhibiting enzymes that damage skin.

To find out if piperine (the active ingredient in black pepper) could help the body absorb more EGCG, the main beneficial compound in green tea

Male mice were given EGCG either alone or with piperine. Researchers measured EGCG blood levels at 60, 90, and 180 minutes and tested EGCG uptake in the small intestine.

Taking piperine with EGCG increased how much EGCG reached the bloodstream by 30%. The small intestine absorbed nearly 3 times more EGCG when piperine was added. Piperine also slowed down how quickly EGCG was broken down by the body and gave it more time to be absorbed in the gut.

To explain how piperine (BioPerine®) works as an absorption enhancer across vitamins, minerals and nutrients, and examine how it works.

Comprehensive mechanistic review of piperine/BioPerine effects on intestinal cells, enzymes, microvilli, membrane fluidity and transport pathways.

Standardized BioPerine® (95% piperine) improved absorption through several different pathways in your gut. It generates localized heat that triggers helpful hormones, makes cell membranes more flexible so nutrients pass through easier, lengthens the tiny finger-like structures in your intestines (giving you more surface area to absorb nutrients), and increases the activity of transport enzymes that carry nutrients into your cells.

To test whether an enhanced delivery formulation improves green tea extract effects on metabolism and fat tissue markers, which would prove better delivery and uptake.

Systematic review of studies Jan 2013–Dec 2023: 21 articles including human RCTs and lab studies assessing topical and oral green tea interventions.

Fat burning increased by 11% compared to placebo. Daily calorie burn at rest went up by 83 calories. Waist circumference dropped by 1 cm. Insulin levels and insulin resistance both improved. These measurable improvements show that the body was getting better tissue exposure and uptake of EGCG.