Green Tea

The Combined Effect of Green Tea and α-Glucosyl Hesperidin in Preventing Obesity: A Randomized Placebo-Controlled Clinical Trial

Study: A 2021 randomized, placebo-controlled, double-blind, parallel-group trial (NCT03628937) in Japan involving 60 healthy adults (aged 30–75) with BMI ≥23 kg/m². Participants consumed green tea with α-glucosyl hesperidin (GT-gH, containing 146 mg EGCG and 178 mg α-glucosyl hesperidin) or placebo daily for 12 weeks. Outcomes included visceral fat area (VFA), body weight, BMI, and lipid profiles.

Findings: GT-gH significantly reduced VFA (mean difference: -7.2 cm², p=0.019) and body weight (p<0.05) compared to placebo. Lipid profiles (e.g., LDL cholesterol) improved slightly. Safety assessments (vital signs, hematology, liver/renal function) showed no significant differences between groups. Side effects were minimal, with no serious adverse events; mild gastrointestinal issues (e.g., bloating) were reported in some participants.

Link: Nature - Combined Effect of Green Tea and α-Glucosyl Hesperidin

Effect of Green Tea Supplementation on Antioxidant Status in Adults: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Study: A 2021 meta-analysis of 16 RCTs (17 arms, 760 participants) evaluating green tea’s effects on oxidative stress markers (total antioxidant capacity [TAC] and malondialdehyde [MDA]). Databases (PubMed, Scopus, Embase, Web of Science) were searched up to August 2021. Studies included healthy, obese, diabetic, and hypercholesterolemic adults, with green tea or green tea extract (GTE) doses ranging from 80–1344 mg/day.

Findings: Green tea significantly increased TAC (WMD: 0.20 mmol/L, 95% CI: 0.09–0.30, p<0.001), with effects stronger in males, females, and both sexes, and at doses >400 mg/day. No significant effect on MDA (WMD: -0.00 μmol/L, p=0.636), though a dose-dependent inverse association was noted (p=0.017). Side effects were mild, including skin rashes, gastric disturbances, and abdominal bloating, with no serious adverse events reported.

Link: MDPI - Green Tea Supplementation on Antioxidant Status

The Effects of Green Tea Supplementation on Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis

Study: A 2023 meta-analysis of 55 RCTs (63 effect sizes) investigating green tea’s effects on cardiovascular risk factors (lipid profile, blood pressure, glycemic control, CRP). Databases (PubMed, Scopus, Web of Science, Embase) were searched for RCTs. Doses varied, with subgroup analyses for <1000 mg/day vs. ≥1000 mg/day and duration (<12 vs. ≥12 weeks).

Findings: Green tea significantly reduced total cholesterol (WMD: -7.62 mg/dL, p<0.001), LDL cholesterol (WMD: -5.80 mg/dL, p<0.001), fasting blood glucose (WMD: -1.67 mg/dL, p<0.001), and increased HDL cholesterol (WMD: 1.85 mg/dL, p=0.010). Effects were stronger at doses <1000 mg/day and in females or mixed-sex groups. Side effects were not extensively detailed but included mild gastric disturbances in some trials, with no serious adverse events noted.

Link: Frontiers - Green Tea Supplementation on Cardiovascular Risk Factors

Decaffeinated Green Tea Polyphenols Supplementation Had No Adverse Health Effects in Girls with Obesity: A Randomized Controlled Trial

Study: A 2024 RCT (NCT03628937) in China involving 62 girls with obesity (aged 6–10). Participants received 400 mg/day decaffeinated green tea polyphenols (DGTP) or placebo for 12 weeks. Outcomes included anthropometric measures, liver/renal function, and safety parameters (e.g., vital signs, blood glucose).

Findings: DGTP showed no significant changes in body weight, BMI, or lipid profiles compared to placebo. Safety assessments confirmed no adverse effects on liver (AST, ALT), renal (BUN, creatinine), or hematological parameters. No serious adverse events were reported; mild gastrointestinal discomfort (e.g., nausea) was noted in a few participants.

Link: PMC - Decaffeinated Green Tea Polyphenols in Girls

The Impact of Green Tea Supplementation on Anthropometric Indices and Inflammatory Cytokines in Women with Polycystic Ovary Syndrome

Study: A 2017 RCT involving 45 women with PCOS, randomly assigned to green tea tablets (dose not specified) or placebo for 45 days. Outcomes included anthropometric indices (BMI, weight, waist circumference, body fat percentage) and inflammatory markers (IL-6, CRP, TNF-α).

Findings: Green tea significantly reduced BMI, weight, waist circumference, and body fat percentage within the green tea group (p<0.05), but no significant differences were observed between groups. No effect on inflammatory markers (IL-6, CRP, TNF-α). Side effects were minimal, with mild gastric disturbances reported in some participants, similar to placebo.

Link: PubMed - Green Tea in PCOS

Green Tea as a Safe Alternative Approach for Nonalcoholic Fatty Liver Treatment: A Systematic Review and Meta-Analysis of Clinical Trials

Study: A 2018 meta-analysis of RCTs (searched up to October 2017 via PubMed, Scopus, Web of Science, Google Scholar) evaluating green tea’s effects on nonalcoholic fatty liver disease (NAFLD). Outcomes included liver enzymes (ALT, AST), lipid profiles, BMI, and insulin resistance.

Findings: Green tea significantly reduced BMI (-2.08 kg/m², 95% CI: -2.81 to -1.36), triglycerides (-31.87 mg/dL), total cholesterol (-27.57 mg/dL), and LDL cholesterol (-14.15 mg/dL). No significant effect on HDL or insulin resistance. Side effects were mild, primarily gastrointestinal (e.g., bloating, nausea), with no serious adverse events reported.

Link: PubMed - Green Tea in NAFLD