Daily watermelon juice intake not enough to benefit vascular function in women

Drinking pure watermelon juice everyday does not appear to produce significant improvements in the vascular function of healthy postmenopausal women, as shown in a study.

Twenty-one women were randomized to consume two 360-mL servings of 100% watermelon juice per day or an isocaloric placebo for 4 weeks. Following a two-week washout period, the women consumed the other beverage for an additional 4 weeks.

Researchers collected a fasting blood sample before and after each treatment intervention to measure serum arginine, citrulline, lycopene, glucose, and insulin. They also assessed vascular function, including pulse pressure, pulse wave velocity, 24-h ambulatory blood pressure, and flow-mediated dilation.

General linear mixed models revealed that the consumption of pure watermelon juice led to a marked increase in circulating lycopene concentrations (p=0.002) but not in arginine and citrulline. Furthermore, there were no significant between-treatment differences documented in any vascular measures.

Juice supplementation produced a slight but significant increase in fasting serum glucose (p=0.001), but the changes in glucose homeostasis were not clinically significant.

Watermelon juice has been shown to be a rich food source of cardioprotective compounds, including arginine, citrulline, and lycopene. However, the present data provide no evidence of cardioprotection with watermelon juice supplementation in postmenopausal women whose age puts them at risk of vascular dysfunction.