Abstract
BackgroundThe results of the studies that have investigated the effects of black tea on blood cholesterol are inconsistent. The aim of this study is to quantitatively assess the effects of black tea on cholesterol concentrations.MethodsPubMed, Embase, MEDLINE, and Cochrane Library (through to July 2014) were searched for randomized controlled trials (RCTs) designed to investigate the effect of black tea on blood cholesterol concentrations. The study quality was assessed by the Jadad scoring criteria. Pooled effect of black tea consumption on blood cholesterol concentrations was evaluated by fixed-effects or random-effects model. Meta-regression analyses were conducted to estimate dose effects of black tea polyphenols on concentrations of blood cholesterol. Subgroup and sensitivity analyses were performed to assess the potential source of heterogeneity.ResultsThe consumption of black tea did not significantly lower TC concentrations either in healthy subjects or patients with coronary artery diseases based on both fixed-effects and random-effects analysis. No significant change was observed in HDL-C concentrations in healthy participants or in subjects with coronary artery disease supplemented with black tea when compared with control participants. The pooled net change of LDL-C in healthy participants was −5.57 mg/dL (95% CI, −9.49 to −1.66 mg/dL; P = 0.005) in fixed-effects analysis and −4.56 (95% CI, −10.30 to 1.17 mg/dL; P = 0.12) in random-effects analysis. No significant net change was observed in LDL-C concentrations in patients with coronary artery disease. Subgroup and sensitivity did not significantly influence the overall outcomes of this meta-analysis. No significant dose effects of black tea polyphenols on blood cholesterol concentrations were detected in meta-regression analyses.ConclusionThe meta-analysis suggests that the consumption of black tea might not have beneficial effects on concentrations of TC, HDL-C, and LDL-C. Further high quality RCTs are needed to definitively draw a causal interpretation of the findings.
Highlights
Cardiovascular diseases (CVD) account for almost 50% of non communicable diseases, which have exceeded communicable diseases as the major disease burden worldwide
7 studies did not report the data of concentrations of total cholesterol (TC), HDL-C, or low-density lipoprotein-cholesterol (LDL-C), 6 studies had short treatment duration (,2 weeks), and 6 studies used a multi-component supplement containing black tea in intervention group
Of the 15 trials included in our meta-analysis, 11 selected healthy subjects, 2 included the patients with coronary artery disease, 1 included the subjects with diabetes and 1 included the participants with diabetes or with two other cardiovascular risk factors
Summary
Cardiovascular diseases (CVD) account for almost 50% of non communicable diseases, which have exceeded communicable diseases as the major disease burden worldwide. Low high-density lipoprotein-cholesterol (HDLC) concentrations and high total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) concentrations are the major risk factors of CVD [4,5,6,7,8]. A recent study suggests that a 1% reduction of cholesterol can decrease the risk of CVD by 3% [9], whereas hyperlipidemia may increase the heart attack risk by 3-fold [10], indicating that the effective regulation of cholesterol metabolism will reduce the burden of CVD. The results of the studies that have investigated the effects of black tea on blood cholesterol are inconsistent. The aim of this study is to quantitatively assess the effects of black tea on cholesterol concentrations
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