The Science of Aphrodisiacs

They've been touted to increase sex drive, boost arousal, and put men and women in the "mood" for hundreds of years. But the skeptical consider aphrodisiacs—foods, drinks, and now cleverly marketed extracts and supplements—to be more mental than physical. A brief look at some of the more notorious of these purported libido enhancers reveals both flimsy claims and some sound science.

Watermelon. A study suggesting that watermelon may have Viagra-like effects on the body made headlines last month. But the findings don't exactly mean that eating watermelon can boost libido or treat erectile dysfunction. Watermelon, scientists found, contains large amounts of the plant nutrient citrulline, which is known to have beneficial effects on the cardiovascular and immune systems. The chemical can relax blood vessels and improve blood flow, in much the way Viagra's active ingredient does. But, the researchers say, it isn't as organ specific as Viagra. Also, most of watermelon's citrulline is found in the inedible rind of the fruit.

Oysters. Since ancient times, many people have considered these mollusks to be an especially potent aphrodisiac. But this reputation may have arisen simply because an oyster's shape resembles the female genitalia. (The same may be true of figs and avocado.) There's no scientific evidence that the slippery mollusks boost libido or sexual performance. However, oysters have a high zinc content, which is essential to the production of testosterone, the male sex hormone, and the maintenance of healthy sperm. Pine nuts, also considered an aphrodisiac by some, contain large amounts of zinc relative to other nuts.

Hot peppers. A group of alleged aphrodisiacs—cayenne and other chili peppers—is sometimes sold in the form of an extract, but its effect on the body may be more discomfort inducing than arousing. The fiery fruits contain varying levels of a chemical irritant called capsaicin, which, when ingested, causes an increase in heart rate and breathing, sweating, and blood flow—similar to the body's response to sexual arousal.

Chocolate. Perhaps the most famous—and most studied—of the aphrodisiacs is chocolate. A 2006 study published in the Journal of Sexual Medicine found that women who habitually ate chocolate on a daily basis reported higher sexual function scores than those who did not. Researchers believe this finding is a misleading artifact of chocolate eaters' tendency to be younger—and have naturally higher libidos—than people who avoid the treat. Interestingly, there was no difference between the groups in sexual arousal or satisfaction. Still, it's plausible that chocolate contains a little love mojo: The neurotransmitters serotonin and anandamide both contribute to feelings of happiness and euphoria during sex. And both are found in chocolate.