(HealthScoutNews) -- A pioneering study of diet and the enlargement of the prostate gland that bothers many older American men has yielded a recommendation that's common these days: Reduce your calorie intake and you might reduce the problem.

The prostate is a chestnut-shaped male organ that surrounds part of the urethra, the tube through which urine flows. It often starts to enlarge after age 50, causing problems that force many men to get up once or twice a night to urinate.

"This is probably the most comprehensive study of diet and prostate enlargement ever done," says Dr. Edward Giovannucci, associate professor of medicine at Harvard Medical School, and leader of the group reporting the results in the current American Journal of Clinical Nutrition.

The findings come from the Health Professionals Follow-up Study, which followed more than 33,000 men for nearly a decade. Giovannucci and his colleagues looked at the relationship between the detailed dietary information the men gave and the incidence of benign prostate hyperplasia, the formal name for an enlarged prostate ("benign" meaning the condition isn't cancerous).

"The associations we saw were statistically significant but relatively modest," Giovannucci says. "They are worth pursuing, but they are only part of the whole picture."

One intriguing finding linked increased risk of enlargement to intake of polyunsaturated fatty acids, the kind that are found in fish and related to a reduced risk of heart disease. Giovannucci downplays that association: "It is relatively modest and it does not supersede the recommendations for preventing heart disease," he says.

But that finding offers a clue that could lead to new treatments for the condition, Giovannucci says. Prostate enlargement now is treated either with alpha blocker drugs, which cause muscle relaxation, or anti-androgens, which counteract the effect of male hormones. If neither treatment works, surgery is a last resort.

"These polyunsaturated fatty acids could increase the susceptibility of cells to oxidative stress, causing inflammation," Giovannucci says. "What we are pursuing now is to see whether antioxidants such as vitamin E and selenium might offset the increased risk."

One decidedly noncontroversial finding was that "higher calorie intake was associated with increased risk," he says.

That's a critical point, says Dr. David Heber, professor of medicine and director of the University of California at Los Angeles Center for Human Nutrition. He's also the author of an accompanying editorial in the journal.

"It is an interesting clue toward the relationship between inflammation and the American diet," Heber says. "If you are overweight, that fat tissue stimulates inflammation, and it may also stimulate prostatic hyperplasia."

Fat tissue produces estrogen, the female hormone that can contribute to prostate enlargement, Heber says. He suggests that the low fruit and vegetable content of the American diet, with more calories coming from animal fat, could explain the higher incidence of prostate enlargement in the West than in Asia, where diets include more fruits and vegetables.

What To Do

Male or female, young or old, limiting calorie intake and eating lots of fruits and vegetables (five servings a day are recommended) can do you plenty of good.

For more information on the prostate and its problems, visit the National Institute of Diabetes and Digestive and Kidney Diseases, or the National Library of Medicine.

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