Does eating too much lead to urinary incontinence?

Women who consume a lot of calories or favor saturated fat over “good” fats may have an increased risk of urinary incontinence, regardless of their body weight, a new study suggests.

The findings don’t prove that diet changes can help prevent or manage urinary incontinence, the researchers say.

The findings, they say, also point to a relationship between dietary factors and incontinence risk that is independent of weight.

Excess weight, particularly in the abdomen, is one risk factor for urinary incontinence, and shedding those extra pounds can help prevent the problem or reduce symptoms. But it’s also possible that the healthy lifestyle changes that spur weight loss - improved diet and increased exercise - help explain the benefit.

To look at that question, the researchers on the current study used data from a health survey of 2,060 Boston women, 30 to 79 years old, who gave detailed information on their diets and other lifestyle habits. The women were also questioned about any urinary symptoms, and had their weight, height and waist circumference measured.

Overall, the study found, just over 12 percent of the women had moderate-to-severe urinary incontinence - problems with leakage at least once a week, or significant leakage once a month.

The risk was nearly three times higher among the 20 percent of women with the highest average calorie intake versus those who consumed the fewest calories. A similar increase was seen among women who got a high proportion of their dietary fat from saturated fat - which is found primarily in animal products - and relatively little polyunsaturated fat, found in vegetable oils.

That was true, the researchers found, even after taking into account the women’s weight, as well as other factors such as age, race and major medical conditions like heart disease and diabetes.

“These are pretty novel findings, and we need more research to verify them,” said lead researcher Dr. Nancy N. Maserejian, of the New England Research Institutes in Watertown, Massachusetts.

That should include clinical trials to see whether cutting calories and saturated fat does in fact improve urinary incontinence symptoms, Maserejian told Reuters Health.

For now, she noted that for people who are overweight, weight loss remains the “first-line” lifestyle therapy for incontinence. But the current findings suggest that shedding pounds with the help of calorie-cutting and trading saturated fat for polyunsaturated fats may be especially effective.

They also suggest that such diet changes could prove effective for normal-weight women, according to Maserejian. “One of the interesting things about our findings,” she said, “is that the association (between calories and urinary incontinence) was even stronger among lean women.”

Exactly why the balance of fats in a person’s diet would affect urinary incontinence risk is not clear. But it may have to do with chronic, systemic inflammation, Maserejian and her colleagues speculate.

Studies have found that people with higher levels of certain inflammatory substances in their blood are more likely to have urinary tract symptoms. And it’s believed that diets with a high ratio of saturated fat to polyunsaturated fat may promote inflammation.

Excess calories, meanwhile, might affect urinary symptoms because more calories mean more nervous-system activity - which could increase firing in the nerves that affect the bladder, Maserejian explained.

Of all women in the study, the 20 percent with highest calorie intakes typically consumed about 2,400 calories per day. Compared with the group with the lowest calorie intake - 840 calories per day - these women were almost three times more likely to have urinary incontinence, with other health and lifestyle factors considered.

Meanwhile, women with the highest ratios of saturated to polyunsaturated fats consumed anywhere from three to seven times more saturated fat than polyunsaturated. They were 2.5 times more likely to have urinary incontinence, compared with women who got equal proportions of the two fats. The findings are published in the American Journal of Epidemiology.

Maserejian suggested that women try to moderate their calorie intake and swap sources of saturated fat - like meat and butter - for plant-based fats. While it is not yet known if those changes will prevent or treat urinary incontinence, she noted, they are generally healthy measures anyway.


American Journal of Epidemiology, online April 25, 2010.

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