Supplementary intake of green tea extract for >8 weeks may improve the lipid profile of individuals with type 2 diabetes (T2D), according to results of a meta-analysis published in Diabetes & Metabolic Syndrome: Clinical Research & Reviews.
Studies have suggested that the catechins found in green tea extract may improve glucose homeostasis in individuals with T2D, but clinical trials on the efficacy of green tea extract or its components in improving the lipid profile of individuals with T2D have had conflicting results.
To assess the effects of green tea extract on lipid profile in patients with T2D, a systematic review and meta-analysis of 7 studies was conducted. Randomized controlled trials with a treatment duration ≥2 weeks were included. The quality and risk for bias of the included studies were independently evaluated by 2 researchers. A random-effects model was used to calculate the weighted mean differences (WMDs) between studies.
The included studies contained data from a total of 512 individuals. The mean age of included individuals ranged from 50.2 to 64.9 years, mean body mass index from 24.0 to 30.4 kg/m2, study duration from 4 to 16 weeks, and daily dose of green tea extract from 400 to 10,000 mg/d.
Subgroup analyses that stratified studies by duration and green tea dose showed that serum triglyceride concentrations significantly decreased with daily supplementation of ≥800 mg of green tea extract (WMD, -3.52 mg/dL; 95% CI, -4.09 to -2.94; P <.001) and supplementation for >8 weeks (WMD, -26.82 mg/dL; 95% CI, -45.33 to -8.32; P =.004). The researchers also found that total cholesterol concentrations significantly decreased with daily supplementation of <800 mg of green tea extract (WMD, -14.25 mg/dL; 95% CI, -23.70 to -4.80; P =.003) or supplementation for >8 weeks (WMD, -11.14 mg/dL; 95% CI, -20.93 to -1.34; P =.026). Green tea extract supplementation was not shown to significantly affect low-density or high-density lipid levels at any dose or treatment duration.
This meta-analysis showed that long-term supplementary intake of green tea extract may improve aspects of the lipid profile of individuals with T2D by lowering triglyceride and total cholesterol concentrations. The researchers suggested that the variation in their results with regard to dose and duration effectiveness may have been caused by heterogeneity in dosing, caffeine content, ethnicity, and baseline lipid levels in the included studies. Additional long-term randomized controlled trials to confirm these findings are warranted.
Asbaghi O, Fouladvand F, Moradi S, Ashtary-Larky D, Choghakhori R, Abbasnezhad A. Effect of green tea extract on lipid profile in patients with type 2 diabetes mellitus: a systematic review and meta-analysis. Diabetes Metab Syndr. 2020;14(4):293-301.