Apple or apple polyphenol consumption improves cardiovascular disease risk factors: a systematic review and meta-analysis

Many fruits and vegetables have been found to have a protective effect against cardiovascular diseases. We conducted a systematic review and meta-analysis to determine the relationship between apple or apple polyphenol intake and cardiovascular disease risk. The PubMed, Embase, Cochrane, and Web of Science databases were searched up to August 4, 2020. Studies that had an intervention time of >1 week; used apple or apple polyphenols as the intervention; were designed as a randomized controlled trial; and measured blood pressure, cholesterol, and blood glucose levels were included. The meta-analysis showed that the group with apple or apple polyphenol intake had significantly higher high-density lipoprotein levels (standardized mean difference [SMD] = 0.34, 95% confidence interval [CI] [0.01, 0.67], p = 0.0411, I2 = 77%, random-effects model) and significantly lower C-reactive protein levels (SMD = -0.43, 95% CI [-0.65, -0.20], p = 0.0002, I2 = 18%, fixed-effects model) than the control group, indicating that the intervention reduced the risk of cardiovascular diseases. Apple or apple polyphenol intake is associated with a reduced risk of cardiovascular diseases. These results are consistent with the old saying that eating an apple a day can help keep the doctors away.