Natural Viagra?

Watermelon may be a natural viagra, a United States researcher said. that is because the fruit is richer than previously believed in an amino acid called citulline, which relaxes and dilates blood vessels much like Viagra and other drugs used to treat erectile dysfunction.

Until recently, Dr Bhimu Patil, director of the Fruit and Vegetable Improvement Center at Texas A&M University, told WebMD, scientists thought most of the citrulline was in the watermelon rind. But it is now known that there is more citrulline in the flesh too.Citrulline is converted to arginine in the body. This boosts nitric oxide, which relaxes blood vessels - the same basic that Viagra has to treat erectile dysfunction, he said.

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"Watermelon may not be organ-specific, but it's a great way to relax blood vessels without any side-effects."

But how much watermelon must be consumed before the Viagra effect kicks in? Dr Patil has no answer yet.

Citrulline is found in all colors of watermelon and is highest in the yellow-fleshed types, said Penelope Perkins-Veazie, a USA researcher in Lane, Okla. She said Patil's research is valid, but with a caveat: One would need to eat about six cups of watermelon to get enough citrulline to boost the body's arginine level.

Citrulline is present in other curcubits, like cucumbers and cantaloupe, at very low levels, and in the milk protein casein. The highest concentrations of citrulline are found in walnut seedlings, Perkins-Veazie said.

However, sceptics like Dr Roger Clemens, adjunct professor of pharmacology and pharmaceutical science, University of Southern California, Los Angeles, said it is premature to call watermelon a natural Viagra. He had studied arginine, researching a supplement to improve vascular flow for patients with hardening of the arteries, but has since abandoned that line of research, he said.