Effect of Watermelon on Cardiometabolic Health

Both hypertension and oxidative stress are among the major risk factors for cardiovascular disease (CVD). While CVD is a multifactorial disease, it has been established that diet plays an integral role in its pathogenesis. In fact, it has been previously demonstrated that almond and pomegranate consumption may be able to strengthen the body's antioxidant defense mechanisms and aid in improving several cardiometabolic health biomarkers. Watermelon, being rich in fiber, vitamins, minerals, and bioactive compounds (e.g., L-citrulline, lycopene, beta-carotene) may also have similar health effects. Notably, studies involving both mice and humans have demonstrated the potential of watermelon consumption to prevent CVD by lowering blood pressure and low-density lipoprotein cholesterol (LDL-C). Emerging evidence suggests that postprandial biomarker levels may serve as better and earlier predictors of CVD development than their fasting levels. While watermelon is often consumed with or after a meal, no studies have evaluated the effect of watermelon on postprandial biomarker responses after a meal challenge. In addition, despite the high bioactive content of watermelon, its effects on whole-body antioxidant capacity have not been explored yet. Therefore, in the present study it is proposed to evaluate the acute (postprandial) and chronic (4 weeks of daily consumption) effects of 355 ml of watermelon juice (WMJ) on: 1) cardiometabolic risk factors including blood pressure, heart rate, pulse wave velocity (PWV), blood glucose and lipids/lipoproteins, nitric oxide (NO), insulin/C-peptide, and GLP-1; and 2) whole-body antioxidant capacity by evaluating skin resistance to UV irritation, as well as blood and urine malondialdehyde (MDA) levels. A two-phase intervention study (2-week standardization phase and a 4-week intervention phase) involving 20 generally healthy non-vegetarian/vegan postmenopausal women with slightly elevated blood pressure, overweight/obese BMI, and Fitzpatrick's skin types II-IV will be performed. Investigating the effects of WMJ consumption on cardiometabolic risk factors and skin antioxidant defense/systemic oxidative status will uncover valuable new insights into whether bioactive compounds in watermelon can affect cardiometabolic risk and contribute to the total body antioxidant capacity.