The effect of watermelon supplementation on blood pressure: a meta-analysis of randomised clinical trials

Aims: This study aimed to summarise earlier randomised-controlled trials on the effects of watermelon supplementation on blood pressure (BP) in adults. Methods: A systematic search was performed in electronic databases including PubMed, Scopus, and ISI Web of Science up to May 2021. To compare the effects of watermelon with control, differences in weighted mean difference (WMD) with 95% confidence intervals (95% CI) were pooled using the random effects model. Results: Overall, six trials were included. The pooled analysis demonstrated significant decreases in systolic BP (SBP) (WMD: −10.55 mmHg; 95% CI: −15.30 to −5.80, P < 0.001) and diastolic BP (DBP) (WMD: −5.22 mmHg; 95% CI: −9.82 to −0.62, P = 0.02) after watermelon supplementation. There was a significant heterogeneity between studies for SBP (I² = 91.1%; P < 0.001) and DBP (I² = 97.3%; P < 0.001). Conclusion: In summary, the present meta-analysis confirms that watermelon supplementation has BP-lowering effects. Nevertheless, due to the limited availability of studies and relatively small sample sizes, well-designed trials with adequate sample sizes aimed at hypertensive and prehypertensive patients are recommended.