Effect of green tea consumption on blood lipids: a systematic review and meta-analysis of randomized controlled trials

Abstract

Background Strong epidemiologic evidence indicates that green tea intake is protective against hyperlipidemia; however, randomized controlled studies have presented varying results. In the present study, we aimed to conduct a literature review and meta-analysis to assess the effect of green tea on blood lipids. Methods PubMed, Embase, and the Cochrane Library were electronically explored from inception to September 2019 for all relevant studies. Random effect models were used to estimate blood lipid changes between green tea supplementation and control groups by evaluating the weighted mean differences (WMD) with 95% confidence intervals (CIs). The risk of bias for study was assessed using the Cochrane tool. Publication bias was evaluated using funnel plots and Egger’s tests. Results Thirty-one trials with a total of 3321 subjects were included in the meta-analysis. In general, green tea intake significantly lowered the total cholesterol (TC); WMD: − 4.66 mg/dL; 95% CI: − 6.36, − 2.96 mg/dL; P < 0.0001) and low-density lipoprotein (LDL) cholesterol (WMD:− 4.55 mg/dL; 95% CI: − 6.31, − 2.80 mg/dL; P < 0.0001) levels compared with those in the control. Green tea consumption did not affect high-density lipoprotein (HDL) cholesterol; however, it reduced the triglycerides compared with that in the control (WMD: − 3.77 mg/dL; 95% CI: − 8.90, 1.37 mg/dL; P = 0.15). In addition, significant publication bias from funnel plots or Egger’s tests was not evident. Conclusions Collectively, consumption of green tea lowers LDL cholesterol and TC, but not HDL cholesterol or triglycerides in both normal weight subjects and those who were overweight/obese; however, additional well-designed studies that include more diverse populations and longer duration are warranted.

COVID -19: could green tea catechins reduce the risks?

“…At this level, this is presumably the first evidence supporting the idea that green tea constituents may reduce the risks related to COVID-19. These results are in agreement with several lines of emerging evidence implying that green tea catechins may be effective in prevention/treatment of COVID-19 or amelioration of its severity [6][7][8][9][10]13 (as outlined in the Introduction).…”

“…7 Additionally, several factors associated with COVID-19 mortality are likely to be affected by green tea constituents. Indeed, there is evidence that green tea catechins: lower cholesterol levels; 8,9 have anti-diabetic 10 and anti-obesity effects; 11 are beneficial in cardiovascular disease 12 .…”

Tea intake and cardiovascular disease: an umbrella review

“…No effects were reported for green tea vs. placebo or black tea vs. placebo [ 24 ]. Xu et al found a significant decrease in total cholesterol among normal weight, overweight, and obese individuals (combined) who consumed green tea vs. placebo (weighted mean difference [WMD]: −4.66 mg/dL; 95% CI: 6.36 to −2.96; p = .0001) in a random effects meta-analysis [ 31 ]. The remaining nine older systematic reviews found no significant effects on total cholesterol across various populations [ 3 , 11 , 18 , 19 , 22 , 27 , 30 , 34 , 49 ], which may be due to a smaller number of studies and overall sample size.…”

Botanicals Reduce Circulating Concentrations of Cholesterol and Triglycerides and Work Synergistically With Arachidonic Acid to Reduce Inflammatory Cytokines in Cats

“…This suggests that there is some fatty acid pathway that potentiates the botanical response and is suggestive for further research. The anti-inflammatory effects of the botanical extracts in attenuating inflammation was expected based on their reported effects in other species ( 11 – 16 ). However, the robust combined effects of the three extracts with ARA on some of the cytokines was novel and not to our knowledge previously reported.…”

“…In a meta-analysis of human studies it was concluded that green tea intake lowered total cholesterol and low density lipoprotein cholesterol while not influencing high density lipoprotein cholesterol. However, there was a need for greater diversity within the study population and longer duration studies ( 16 ). This study in cats tests the combination of botanical extracts to exert a beneficial effect using cytokines and selected blood parameters as response criteria.…”