Female Sexual Function

In a textbook example of how to make money off a disease, the pharmaceutical industry markets female sexual dysfunction as a mental disorder, recalling the first edition of the Diagnostic and Statistical Manual of Mental Disorders, the psychiatry diagnostic manual, which listed frigidity and homosexuality as mental disorders. The latest label is "hypoactive sexual desire disorder," a disease invented by pharmaceutical companies. Certainly, there are women affected by low libido, but that does not make it a disease. Even women with normal libido can be diagnosed with "hypoactive sexual desire disorder": "A woman who is very interested in sex, just not with her current partner, still qualifies for this diagnosis"—and for the drug. The same applies to "a woman who is satisfied with her sex life, but her partner is not …".

In my video see.nf/hsdd I discuss the shameful history of the approval of flibanserin (brand name Addyi). Its clinical benefit is marginal; the side effects are considerable. In combination with alcohol, for example, it can cause dangerously low blood pressure and fainting spells—problems so serious that the FDA placed a black box warning—their highest level of warning—on the drug’s package insert, which hardly anyone reads. Even without alcohol, there can be a sharp drop in blood pressure and "sudden, prolonged loss of consciousness." As Adriane Fugh-Berman, professor of pharmacology, put it, such serious side effects are "perhaps acceptable for a cancer drug, but completely unacceptable for a drug given to healthy women for an invented disease."

Get Your Juices Flowing

A healthier diet can extend not only your life, but also your sex life. In general, lifestyle changes that benefit heart health are also changes that benefit sexual health, because blood flow plays a crucial role in the sexual responses of both men and women. Researchers can, for example, use MRI technology to measure the swelling of the clitoris within minutes while watching an erotic video. This explains why vascular disease significantly impairs female sexual function. It is caused by atherosclerotic narrowing of blood flow and arterial dysfunction. Rabbits made atherosclerotic by being fed cholesterol suffer a decrease in induced clitoral erections. (Yes, all female mammals have a clitoris, as do some birds and reptiles.)

Cholesterol doesn’t just build up in the arteries that supply the heart muscle, but in all blood vessels. In the heart, atherosclerosis can trigger a heart attack; in the brain, a stroke. In the legs, it can cause peripheral vascular disease and lead to crippling cramps; in the spinal arteries, disc degeneration and low back pain. And blockages in the pelvic arteries can lead to sexual dysfunction, including reduced vaginal blood flow and "clitoral erectile dysfunction," defined as an "inability to bring the clitoris to tumescence," or swelling. This is believed to be an important factor in sexual dysfunction in women.

Women with higher cholesterol levels report significantly weaker orgasm and significantly lower arousal, lubrication (moisture), and sexual satisfaction. The same appears to be true for women with high blood pressure. The Framingham risk score takes into account both cholesterol level and blood pressure, and women with a score indicating a 2-percent 10-year risk of heart disease have nearly double the risk of sexual dysfunction. No wonder that overall sexual function in women improved significantly once they were randomized to plant-rich diets.

Lubrication, too, is all about blood flow. The hydrostatic pressure from the additional pelvic blood flow in a sexually aroused vagina causes fluid to seep out into the birth canal as vaginal lubrication. How can we increase blood flow? You may remember the chapter "Preserving the Mind" and how the flavonoid phytonutrients in cocoa help open the arteries, an effect that peaks about 90 minutes after consumption. So could the Valentine’s Day chocolate be crucial? It was found that women score higher on the female sexual function index when they eat chocolate. However, the effect disappeared once age was factored in. So chocolate doesn’t work as an aphrodisiac—perhaps because fat and sugar cancel out the benefits of the flavonoids in pure cocoa powder.

Which whole foods contain flavonoids? One important source is onions. "Freshly squeezed onion juice" boosts mating behavior—in rodents. Anyone who isn’t interested in how to "increase the percentage of ejaculating rats," and doesn’t want to drink onion juice before a hot date, should reach for apples, the second-largest source of flavonoids in the United States.

An Italian study found that women who ate apples daily scored significantly better on an index of overall female sexual function than women who ate less than one apple per day. The scientists counted only women who ate unpeeled apples, since the phytonutrients are concentrated in the peel. So we don’t know whether there is also an association with peeled apples. In any case, the observational study could show only an association between apple-eating and improved sexual function. Should cause and effect be confirmed, the study suggested, this could lead to the "discovery of new preparations and dietary supplements to restore female sexuality." Or you could just try an apple.

Torn Apart in Midair

Women randomized to eat more fruits, vegetables, nuts, and beans, and to switch from animal to plant sources of fat, experienced a significant increase in sexual function. The same was observed for men and their erectile function. The largest study on diet and erectile dysfunction (ED) found that each additional daily serving of fruit or vegetables lowers the risk of ED by 10 percent. Better blood flow and less inflammation are possible reasons.

A report on inflammation and sexual dysfunction concluded that men and women should switch to a diet rich in fruits, vegetables, whole grains, nuts, and seeds and low in sodium and saturated fat. As I summarized in the chapter on inflammation, fiber is the most anti-inflammatory component of the diet, and saturated fat the most pro-inflammatory. A two-year intervention study that observed a significant improvement in sexual function in men and women once they were randomized to eat healthier also found a significant reduction in levels of C-reactive protein, a marker of systemic inflammation. Even with no change in diet composition, it helps to reduce the amount. Overweight diabetic women with sexual dysfunction were randomized to eat smaller portions and lost 15 pounds in a year. That was enough to lower C-reactive protein levels by about 40 percent and more than double the likelihood of regaining normal sexual function.

However, you don’t have to wait a whole year. Changes in blood inflammation levels can occur from hour to hour, depending on what we have just eaten. Scientists fed some participants sausage-egg-butter-oil sandwiches and others whole-grain pizza without cheese. In our body there is a pro-inflammatory signaling molecule called interleukin-18, which is believed to be involved in destabilizing atherosclerotic plaques. Therefore, the blood level of interleukin-18 is a strong predictor of cardiovascular death. Within just a few hours after eating the sausage sandwich, participants’ interleukin-18 levels rose by about 20 percent. In contrast, among those who ate the vegetarian whole-grain pizza, interleukin-18 levels fell by about 20 percent a few hours after the meal, supporting the dietary recommendation for a high-fiber diet low in saturated fat.