Why does this work?
The amino acid citrulline is converted into the amino acid arginine. This is a precursor for nitric oxide, and the nitric oxide, a blood vessel relaxer that enhances circulation to all your vital parts.
How much watermelon should you eat?
A typical 4-ounce serving of watermelon (about 10 watermelon balls) has about 150 milligrams of citrulline.