The chemicals in watermelon work much like Viagra. Researchers at Texas A&M's fruit and vegetable improvement center have discovered that watermelons have an ingredient citrulline that delivers viagra like Effects and may even increase libido. Apparently, citrulline reacts with the body's enzymes to relax blood vessels. Unlike Viagra, the watermelon effect isn't confined to a specific body part. They say watermelon could also be beneficial for those with high blood pressure and other cardiovascular problems.
However, the phyto-nutrient called citrulline that relaxes the blood Vessels is found in highest concentrations in the part we generally don't eat - the watermelon rind. Would it take like a whole watermelon rind to eat to do any good, you might get yourself sick before you do yourself any good.
But researchers caution that too much watermelon will have you running to the bathroom instead of the bedroom.