The effects of caffeine supplementation on blood pressure in adults: A systematic review and dose-response meta-analysis

Abstract

Hypertension is a serious complication linked to a higher risk for organs. Caffeine is a natural component that affects the cardiovascular system, while the mechanisms of its effects are not fully established. Therefore, we aimed to examine the impact of caffeine supplementation on blood pressure (BP) by conducting a systematic review and dose-response meta-analysis of randomized controlled clinical trials (RCTs). We searched online databases using relevant keywords up to July 2022 to identify RCTs using caffeine on systolic (SBP) and diastolic BP (DBP) in adults. Inclusion criteria were adult participants ≥18 years old for subjects, examining the effect of caffeine supplementation on BP, and RCTs studies. A random-effects model was used to estimate the weighted mean difference (WMD) and 95% confidence (CI). The pooled of 11 effect sizes analysis of 8 studies demonstrated significant increases in SBP (WMD:1.94mmHg; 95%CI:0.52, 3.35; p=0.007) and DBP (WMD:1.66mmHg; 95% CI:0.75, 2.57; p=0.000) after caffeine supplementation. The subgroup analysis showed that caffeine supplementation more effectively increased SBP and DBP in males than females. Moreover, meta-regression analysis demonstrated a significant relationship between the dose of caffeine intake and changes in SBP (p=0.000), DBP (p=0.000), and duration of the trial in SBP (p=0.005), and DBP (p=0.001). The non-linear dose-response analysis detected the dosage of supplementation >400mg/day is effective for increasing DBP (p=0.034), and the duration of supplementation of more than nine weeks makes increasing in both SBP and DBP. This meta-analysis shows that caffeine supplementation significantly increased SBP and DBP in adults.