The LA Times reports "In a small, pilot study led by food scientists at Florida State University, researchers found that eating six grams of watermelon extract a day for six weeks lowered blood pressure in all nine middle-aged subjects with prehypertension — elevated blood pressure, but not yet considered high blood pressure.
Findings from the pilot study are described in the American Journal of Hypertension.
FSU Assistant Professor Arturo Figueroa, the lead researcher and his team tested watermelon extract because watermelon is the richest edible natural source of L-citrulline, which is closely related to L-arginine, an amino acid that's essential to the regulation of healthy blood pressure.
Once in the body, the L-citrulline is converted into L-arginine. Simply consuming L-arginine as a dietary supplement isn't an option for many hypertensive adults, said Figueroa, because it can cause nausea, gastrointestinal tract discomfort and diarrhea.
In contrast, watermelon is well tolerated. Participants in the Florida State pilot study reported no adverse effects.
Besides its vascular benefits, watermelon provides abundant vitamin A, B6, C, fiber, potassium and lycopene, a powerful antioxidant. Watermelon may even help reduce serum glucose levels, according to Professor Bahram H. Arjmandi, who also worked on the study.