"Watermelon as Viagra:" Another Example of Irresponsible Reporting?

First it was oysters; then came the arrival of the most widely touted drug since penicillin, Viagra. Now, according to media reports, watermelon could be the latest weapon in the "war" against erectile dysfunction (ED, defined as the ability to attain or maintain an erection).

Unfortunately, such claims are not supported by scientific evidence.

According to press reports Bhimu Patil, PhD, director of the Fruit and Vegetable Improvement Center at Texas A&M University stated that watermelon could become a natural food or dietary supplement in the treatment of ED because it happens to contain a chemical that appears to be essential to the body's ability to relax or constrict its blood vessels (see note 1).

Dr. Patil based his conclusions on the previously known fact that watermelon is known to contain the amino acid citrulline, which the body metabolizes into another amino acid called arginine, which in turn produces a chemical called nitrous oxide that the body uses to relaxes and dilates blood vessels.

Viagra and other drugs used to treat ED work, in part, by temporarily increasing the level of nitrous oxide in the bloodstream.

What the Original News Item Stated:

The following statements by Dr. Patil are taken verbatim from the original posting at the Texas A & M AgriLife web pages (see note 2):

"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 ... Arginine boosts nitric oxide, which relaxes blood vessels, the same basic effect that Viagra has, to treat erectile dysfunction and maybe even prevent it.

...

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

It must be pointed out that nowhere in the original story does Dr. Patil cite clinical research (research conducted on human volunteers) that supports the media contention that eating watermelon would be of any benefit effect in the treatment of ED. In other words, Dr. Patil was speculating.

The AgriLife story then makes an indirect reference to the fact that "watermelon's phyto-nutrients are being studied by the U.S. Department of Agriculture's Agricultural Research Service in Lane, Oklahoma." While that statement, in the context of the AgriLife story, suggests that those studies support the contention that watermelon could have a Viagra-like effect, the alluded-to study addressed a different topic altogether.

In that research, which measured the effects of watermelon juice consumption on the levels of arginine present in the blood, volunteers were tested before and after a 3-week program in which they were given either 780 or 1,560 grams of watermelon juice daily. At the end of that time, arginine levels in the bloodstream were noted to be 12% and 22% higher, respectively, than those measured at the beginning of the study.

Note that the study was solely concerned with the possible relationship between watermelon and arginine in the bloodstream. It did not address the issue of watermelon having the same effect as Viagra.

Comment:

A bit of simple mathematics will demonstrate that it would be virtually impossible for the average adult to consume enough watermelon to produce any clinical improvements.

780 grams is the metric equivalent of 1½ pounds of juice and 1,560 grams is more than 3 pounds of the same stuff! Since that's watermelon juice, can you begin to imagine how much watermelon you would have to eat to get the same amount of citrulline! Would anyone consuming that much watermelon even feel like finding out if the treatment was actually working?

As noted above, Dr. Patil was merely offering a personal speculation and his claim was not based on clinical evidence. In fact, an online search conducted via the National Library of Medicine's PubMed search engine failed to produce a single report of an applied clinical nature that listed Dr. Patil as either the lead author or as a co-author. How this simple observation eluded the original author of the "watermelon story" is unknown.

It is obvious that, for one reason or another, that the author of the original news story chose to overstate a passing comment that should have been of interest to only a very small sector of the scientific community. Whether this was simply a mistake by that author, or a deliberate exaggeration, is unknown and will not be speculated upon here.

It is a s certain as sunrise that the "Great Watermelon Breakthrough"of 2008 will soon fade from public attention, as soon the story of another irresponsibly-reported "breakthrough" fills the media

Notes:

1. Kathleen Doheny, Watermelon: A Natural Viagra? WebMD, July 1, 2008.

2. Texas A & M University, Watermelon May Have Viagra-Effect: Secrets of Phyto-nutrients are being Unraveled, AgriLife, June 30, 2008.

3. Julie K. Collins et al, Watermelon Consumption Increases Plasma Arginine Concentrations in Adults, Nutrition; March 23, 2007 (3): 261-266.

Disclaimer

The information presented in this article and its included links is of an informational nature only and is not intended as a recommendation of any changes in the reader's health care program. Before making any changes in diet, medications, or other treatments the reader is strongly advised to consult with their health care provider.