“Watermelon has ingredients that deliver Viagra-like effects to the body’s blood vessels and may even increase libido.” When a major university, such as Texas A&M, puts out a press release with such a claim, it is guaranteed to get a great deal of media response. Indeed, news organizations around the world picked up the story, concocting clever headlines such as “No Wonder Watermelons Grow So Big,” “Watermelon, The New Oyster?” and “Watermelon Could Add Bite to Sex Life.” Some even came up with irresponsible, but attention-grabbing headlines like “Watermelon Can Duplicate Viagra Effects.” The problem is that no evidence exists to support these fanciful claims. No study was carried out at Texas A&M, or indeed anywhere else, to demonstrate that watermelon has any such effect. So how did the misleading headlines come about?
Texas A&M carries out research on plant breeding, including that of watermelon. One aim of this research is to investigate the possibility of increasing the naturally occurring amount of an amino acid called citrullin in watermelon. Citrulline is of interest since in the body it can be converted to arginine, an amino acid that plays a role in immune system activity, as well as in the dilation of blood vessels. A press officer at the University, given the task of putting out a release about this rather mundane research, asked watermelon breeder Dr. Bhimu Patil to suggest some interesting items about watermelon that could be included in the press release. Patil then speculated about watermelon increasing levels of arginine in the blood, and mentioned that arginine is the source of nitric oxide, which in turn dilates blood vessels and can increase blood flow. He also pointed out that Viagra works by increasing levels of nitric oxide. Presto, the press officer put two and two together and came up with five, and the press release about watermelon increasing libido was born. Pure mythology. While there is zero evidence abou watermelon having any effect on male performance, the notion of citrulline increasing arginine levels is correct. That was shown in a study published in Nutrition, a respected peer-reviewed journal. Twenty-three volunteers were asked to drink either three or six eight-ounce glasses of watermelon juice a day for three weeks and have their blood tested for arginine. This amount of juice of course corresponds to more watermelon than anyone could reasonably eat. Compared with people who drank no watermelon juice, levels of arginine increased by 12-22%. No physiological consequences of this increase were measured in any way. The point of the research was simply to determine the possibility of increasing arginine levels by diet because of the possible role of this amino acid in improving blood flow. Indeed, there is some evidence that dietary supplements containing arginine can allow blood vessels to dilate more readily, but arginine pills have been linked with nausea and gastrointestinal discomfort. Supplying the body with citrulline, which is then converted into arginine, may get around this problem. But the fact is that no studies have shown that boosting arginine, either through supplements, or through high-citrulline foods has any effect on erectile biology. The only activity that will be stimulated by drinking huge amounts of watermelon juice is urination.
A ripe, sweet watermelon can certainly give a boost to the taste buds, but don’t expect anything else to be boosted. Except sales.