Don’t be fooled by this headline from WebMD Health News reporting a researcher who says that watermelon may be a natural Viagra. 
My Take?
What’s the theory behind how could watermelon be a natural Viagra? The amino acid citrulline is converted into the amino acid arginine, which is a precursor for nitric oxide, and the nitric oxide will help in blood vessel dilation in the penis.
However, the vast majority of American men are not deficient in arginine.
On hearing about the Texas finding, Irwin Goldstein, MD, editor-in-chief of The Journal of Sexual Medicine, was underwhelmed. Suggesting a man feast on watermelon to boost performance, he says, “would be the equivalent of someone dropping a beer bottle in Minneapolis, where the Mississippi River starts, and hoping to see it make an impact on someone in New Orleans.”
“To say that watermelon is Viagra-like is sort of fun,” says Goldstein. “But to even vaguely hope that eating watermelon will alleviate ED is misleading.”
So, if you want to enjoy watermelon on the Fourth of July, that’s great. Just don’t expect any sexual fireworks from doing so.