Men who smoke more than a pack of cigarettes a day had a 60 percent higher risk of impotence than those who never smoked, according to new research.
The Tulane University study, presented March 7 at an American Heart Association conference in Miami, focused on 4,764 men involved in a national health survey in China conducted during 2000 and 2001.
Dr. Jiang He, the lead researcher, says most people know smoking causes cancer and cardiovascular disease.
"But very few people know smoking is also harmful for the sex life," He adds. "Hopefully, our study will remind people smoking is not only bad for the heart and lungs, but also bad for your sex life. This study should provide an additional reason to stop smoking."
He, a professor of epidemiology and medicine at Tulane University School of Public Health and Tropical Medicine, notes that other studies have documented links between smoking and impotence, or erectile dysfunction (ED).
But unlike some other research, the Tulane study adjusted figures to take into account other factors that could contribute to impotence, such as blood pressure, diabetes, cholesterol levels and age.
"After it was adjusted for all of those important risk factors, cigarette smoking was still very strongly associated with ED," He says.
The study found the likelihood of impotence was lower in men who smoked fewer cigarettes, but still much higher than that of non-smokers.
After accounting for possible causes other than smoking, current smokers had a 31 percent overall higher risk of impotence than men who had never smoked, the study says.
Men who smoked fewer than 10 cigarettes a day had a 16 percent higher risk of impotence, compared with those who never smoked, the study found. Those who smoked 11 to 20 cigarettes daily had a 36 percent higher risk, and those who smoked more than 20, a 60 percent higher risk.
The men averaged 47 years old, and all of them reported having sexual relations within the previous six months. The researchers looked at impotence during that time.
He notes that impotence is often linked to atherosclerosis, the build-up of plague that can reduce blood flow in arteries.
Dr. John Spangler, an associate professor of family and community medicine at Wake Forest University School of Medicine, says the new study reinforces the message that smoking isn't good for your sex life.
"I don't know whether men out there really understand that very well," adds Spangler, who has studied links between smoking, high blood pressure and impotence.
"It is a wonderful teaching moment if you say, 'You know if you smoke, that greatly increases your risk of erectile dysfunction.' That's a powerful motive for him to quit," Spangler says.
Smoking, he says, can cause clogging of the arteries in the pelvis area and reduce blood flow to the genitals, which in turn cuts blood flow to the penis, causing impotence.
In a 2001 study, Spangler found that men who smoke and have high blood pressure are 26 more times likely to be impotent than non-smokers. Former smokers with high blood pressure were 11 times more likely to suffer impotence than non-smokers, the study of 59 men also found.
Estimates on the prevalence of impotence in the United States range from 10 million to 20 million men, the National Institutes of Health says. Smoking contributes to other known impotence risk factors, including vascular disease and high blood pressure, experts say.
Diabetes, kidney disease, chronic alcoholism, multiple sclerosis, atherosclerosis, vascular disease, and neurological disease account for about 70 percent of impotence cases, the NIH estimates. Meanwhile, 10 percent to 20 percent of cases stem from psychological causes such as stress, anxiety, guilt, depression, low self-esteem and fear of sexual failure.
Other possible causes of ED include prostate surgery, which can injure nerves and arteries near the penis; injury to the penis, spinal cord, prostate, bladder or pelvis; and medications, including blood pressure drugs, antihistamines, antidepressants, tranquilizers and appetite suppressants.
For more on impotence, visit the National Kidney and Urologic Diseases Information Clearinghouse. For tips on how to quit smoking, check with the American Cancer Society.