Scientists: Watermelon yields Viagra-like effects
By BETSY BLANEY
Associated Press Writer
LUBBOCK, Texas - A slice of cool, fresh watermelon is a juicy way to top off
a Fourth of July cookout and one that researchers say has effects similar to
Viagra - but don't necessarily expect it to keep the fireworks all night
Watermelons contain an ingredient called citrulline that can trigger
production of a compound that helps relax the body's blood vessels, similar
to what happens when a man takes Viagra, said scientists in Texas, one of
the nation's top producers of the seedless variety.
Found in the flesh and rind of watermelons, citrulline reacts with the
body's enzymes when consumed in large quantities and is changed into
arginine, an amino acid that benefits the heart and the circulatory and
"Arginine boosts nitric oxide, which relaxes blood vessels, the same basic
effect that Viagra has, to treat erectile dysfunction and maybe even prevent
it," said Bhimu Patil, a researcher and director of Texas A&M's Fruit and
Vegetable Improvement Center. "Watermelon may not be as organ-specific as
Viagra, but it's a great way to relax blood vessels without any drug side
Todd Wehner, who studies watermelon breeding at North Carolina State
University, said anyone taking Viagra shouldn't expect the same result from
"It sounds like it would be an effect that would be interesting but not a
substitute for any medical treatment," Wehner said.
The nitric oxide can also help with angina, high blood pressure and other
cardiovascular problems, according to the study, which was paid for by the
U.S. Department of Agriculture.
More citrulline - about 60 percent - is found in watermelon rind than in the
flesh, Patil said, but that can vary. But scientists may be able to find
ways to boost the concentrations in the flesh, he said.
Citrulline is found in all colors of watermelon and is highest in the
yellow-fleshed types, said Penelope Perkins-Veazie, a USDA researcher in
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
"The problem you have when you eat a lot of watermelon is you tend to run to
the bathroom more," Perkins-Veazie said.
Watermelon is a diuretic and was a homeopathic treatment for kidney patients
before dialysis became widespread.
Another issue is the amount of sugar that much watermelon would spill into
the bloodstream - a jolt that could cause cramping, Perkins-Veazie said.
Patil said he would like to do future studies on how to reduce the sugar
content in watermelon.
The relationship between citrulline and arginine might also prove helpful to
those who are obese or suffer from type-2 diabetes. The beneficial effects -
among them the ability to relax blood vessels, much like Viagra does - are
beginning to be revealed in research.
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.
"But they're bitter and most people don't want to eat them," she said.