Erectile dysfunction may be a very embarrassing and frustrating condition. But just recently, the experts discovered something that could help men who are suffering from this condition. An amino acid found in watermelons may help relieve erectile dysfunction (ED), according to a Japanese new study. The study suggested that oral L-citrulline supplementation improves erectile dysfunction in rats. The research was published in the Journal of Sexual Medicine and noted on foodconsumer.org. The study, led by Kazunori Kimura, PhD, of the Nagoya City University inf Mizuho-ku, Japan, found that L-citrulline supplements increased serum L-arginine levels and increased nitric oxide.