People often eat watermelon to cool down, but it could help get you heated up, in one way.

Researchers at Texas A&M University said that a substance in the rind of the fruit may relax blood vessels in a manner similar to Viagra, the popular erectile-dysfunction drug.

The substance is a phytochemical called citrulline, according to a news release from the school.

By helping the body create a certain protein called arginine, watermelon has other positive effects, said Dr. Bhimu Patil of the school's Fruit and Vegetable Improvement Center.

"The citrulline-arginine relationship helps heart health, the immune system and may prove to be very helpful for those who suffer from obesity and type 2 diabetes," said Patil.

So while the substance may be able to help in some cases of impotence, it also could ease angina or high blood pressure, Patil said.

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

Other scientists at Texas A&M are working to engineer watermelons with a higher amounts of citrulline in the flesh, which is more commonly eaten.

The release from the university did not say if the amounts that a person could reasonably eat would have any noticeable effect. Often, reports of benefits from certain compounds in foods are based on highly concentrated amounts given to animals, rather than clinical evidence in people.