Does L-citrulline supplementation and watermelon intake reduce blood pressure in middle-aged and older adults? A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE: This study aims to investigate the effects of L-citrulline supplementation and watermelon intake on blood pressure (BP) in middle-aged and elderly individuals. METHODS: Data analysis was conducted using RevMan 5.4.1 software, employing a random effects model to statistically analyze the pooled effect sizes of the obtained systolic blood pressure (SBP) and diastolic blood pressure (DBP) data. Results are reported as weighted mean differences (WMD) with 95% confidence intervals (95% CI). RESULTS: A total of 15 randomized controlled trials (RCTs) investigating the effects of L-citrulline supplementation and watermelon intake on BP in middle-aged and elderly individuals were included, comprising 24 datasets involving 415 participants. The results indicate that L-citrulline supplementation and watermelon intake significantly reduced SBP (-4.02 mmHg [95% CI: -6.54 to -1.50], P = 0.002) and DBP (-2.54 mmHg [95% CI: -4.27 to -0.81], P = 0.004) in the elderly. Subgroup analysis showed that the combined supplementation of L-citrulline and L-arginine significantly decreased SBP (-10.44 mmHg [95% CI: -13.57 to -7.31], P < 0.00001) and DBP (-4.86 mmHg [95% CI: -7.93 to -1.79], P = 0.002) in this population. CONCLUSION: L-citrulline supplementation and watermelon intake overall lowered BP in middle-aged and elderly individuals. Subgroup analysis indicates that the combined supplementation of L-citrulline and L-arginine is superior to L-citrulline or watermelon supplementation alone. These findings provide new dietary recommendations for BP management in the elderly, suggesting that dietary interventions can effectively improve cardiovascular health and reduce the risk of cardiovascular disease (CVD).