Health scientists are becoming more and more interested in the citrulline content of watermelon. Citrulline is an amino acid that is commonly converted by our kidneys and other organ systems into arginine (another amino acid). The flesh of a watermelon contains about 250 millligrams of citrulline per cup. When our body absorbs this citrulline, one of the steps it can take is conversion of citrulline into arginine. Particularly if a person’s body is not making enough arginine, higher levels of arginine can help improve blood flow and other aspects of our cardiovascular health. There’s also some preliminary evidence from animal studies that greater conversion of citrulline into arginine may help prevent excess accumulation of fat in fat cells due to blocked activity of an enzyme called tissue-nonspecific alkaline phosphatase, or TNAP.
A typical 100g portion of watermelon contains 7.6g carbohydrate, 0.15g fat, 0.4g fibre and for just 30 calories.