MONDAY, Aug. 4 (HealthDayNews) -- Erectile dysfunction is common in men over 50 and increases with age, but keeping fit seems to counter the problem.

One-third of the men surveyed in a study appearing in the Aug. 5 issue of the Annals of Internal Medicine reported having problems with an erection in the prior three months. While the incidence of erectile dysfunction (ED) increased about 5 percent each year for all men, the problem was notably less common among men leading healthy lifestyles. For these men, there was about a 10-year delay in ED.

"There's a clear increased risk of erectile dysfunction as people age," confirms study author Eric Rimm, an associate professor of nutrition and epidemiology at the Harvard School of Public Health in Boston. "There is a way to delay the onset of ED, and that's pretty significant."

These ways coincide strongly with ways to prevent or delay other health problems, such as cardiovascular disease and diabetes. That means men need to rely on the old stalwarts of exercising, keeping your body lean and not smoking.

"There is an age-dependent increase but, also, modification of risk factors can affect sexual function. Losing weight, stopping smoking, doing more exercise are associated with better sexual health," says Dr. Andrew McCullough, director of Male Sexual Health, Fertility and Microsurgery at New York University Medical Center in New York City. "We talk so much about treating, treating, treating. Here we're beginning to see an increasing body of evidence that we can modify the appearance of this by changing lifestyle."

Although other studies have looked at ED, this one appears to be the largest (it involved more than 30,000 men) and it included older men, up to the age of 90. "Previous studies included very few men over 70," Rimm points out. "With the aging U.S. population, we wanted to make sure we captured men in the upper age range also." The study was partially funded by Pfizer Inc., which makes the anti-impotence drug Viagra.

Rimm and his team looked at 31,742 men between the ages of 53 and 90 who were part of the Health Professionals Follow-Up Study, a group of male dentists, optometrists, osteopaths, podiatrists, pharmacists and veterinarians. None of the men was known to have prostate cancer and all had completed several questionnaires pertaining to their health, the most recent in 2000.

Thirty-three percent of the participants reported having erectile dysfunction in the previous three months, with ED defined as the inability, without treatment, to have and maintain an erection adequate for sexual intercourse.

Less than 2 percent of the men reporting problems said those problems had occurred before the age of 40, while 4 percent had problems between the ages of 40 and 49. After 50, however, problems increased substantially, with 26 percent of men reporting difficulty between 50 and 59, 40 percent noting it between 60 and 69, and 61 percent of men over 70 saying it was a problem.

Seventy-four percent of men under 59 reported "good" or "very good" sexual function, contrasted with only 10 percent of men over 80.

Men who did the equivalent of three hours of running or more each week or playing five hours of singles tennis reported a 30 percent lower risk of ED, compared with those who did little or no exercise. Watching more than 20 hours of television each week, excessive consumption of alcohol, smoking and being overweight were associated with higher levels of ED, as was having diabetes, previous stroke or taking antidepressants or beta-blockers.

"Exercise as opposed to sitting on your duff watching TV is clearly worthwhile," Rimm says.

The bottom line is that risk factors for ED were about the same as those for heart disease. "One could almost say that erectile dysfunction may be a good marker for cardiovascular disease because of the tie-in with these factors," Rimm says.

Rimm hopes that this news may help change behavior. "A lot of people have known about exercise and obesity and cardiovascular disease and the message is not getting through. The population is getting more overweight," he says. "Maybe people think of cardiovascular disease as too far off, but ED is much more immediate and affects the quality of life. It's something that could affect you every day."

McCullough says, "Since ED is intimately associated with the health of the vascular system, a man needs to have his cardiovascular risk factors thoroughly examined so that maybe we can do some prevention. This clearly shows that prevention can affect erectile function.

"If you ask most people about their erectile function, even if they're overweight, hypertensive and smokers, they'll say 'It's all in my head,' but their body is screaming out to them. The public message is that the penis is a barometer of the health of the vascular system and when it's not working right, you need to listen to that," McCullough says.

The findings may not be entirely applicable to the general population because the men studied tended to be white, highly educated, have higher incomes and have better access to health care than the general population. If anything, sexual dysfunction in the study group was probably lower than in the overall population.