Popular Summer Fruit May Have Viagra-Like Effect on Blood Vessels, According to Research. July 1, 2008 — Skip the burgers and beer at the Fourth of July cookout and eat lots of watermelon instead if you want to see some fireworks in your love life. According to a study, watermelon may be a natural Viagra. That's because the well-known summer fruit contains more citrulline, an amino acid, than experts had anticipated. Citrulline relaxes and dilates blood vessels similarly to Viagra and other medications used to treat erectile dysfunction (ED). According to Bhimu Patil, PHD, head of the Fruit and Vegetable Improvement Center at Texas A&M University, College Station, "We have known that watermelon contains citrulline." According to him, experts previously believed that the watermelon rind contained the majority of the citrulline. The edible section of watermelon has more citrulline than was previously thought, he claims. How is watermelon a potential all-natural Viagra...