Diet content seems key to stemming them in men

For years, experts have recommended both men and women eat a diet low in saturated fats and higher in unsaturated fats to help cut heart disease risk. Now, evidence suggests this diet may have additional benefits for men.

It reduces their risk of gallstones, according to a 14-year study of more than 45,000 men.

The researchers found that men who ate the most unsaturated fats -- like the ones found in vegetables, nuts and seeds -- were 18 percent less likely to develop gallstones than men with the lowest intake of unsaturated fats.

This "good fat" advantage was most pronounced in men who were heavier and less active, the study found.

Gallstones, which affect about one in 12 Americans, develop when bile stored in the gallbladder hardens, forming into stone-like balls. Complications from gallstones can be serious, and even fatal, if left untreated.

The researchers reported that unsaturated fat intake can hamper gallstone formation on the molecular level by making cells more sensitive to insulin, which, in turn, acts to reduce gallstone formation.

"In animal experiments, dietary fats rich in unsaturated fats relative to saturated fats could protect against gallstone formation," Dr. Chung-Jyi Tsai, an associate professor of medicine at the University of Kentucky and lead author of the report, told HealthDay . "We tested the observation in this study."

Participants completed a questionnaire at the start of the study, and again every two years for up to 14 years. They provided information on all aspects of their health, including what they ate and whether they developed gallstones or had to have their gallbladder removed. Tsai and his team compared the number of cases of gallstones in men whose diets had the highest amounts of unsaturated fat with those in men whose diets contained the least amount.

They found a 2-to-1 difference between men in the top 20 percent of unsaturated fat intake and those in the bottom 20 percent. The 18 percent reduction in gallstone formation was found in men who had the highest intake of unsaturated fats.

Participants also were checked for a number of other gallstone risks, including smoking, alcohol intake, physical activity and weight. "There are a number of risk factors associated with gallstone formation," Tsai said. "Intake of unsaturated fats was independently related to gallstone occurrence."

The findings appear to support those of smaller studies on the effect of fat intake on the risk of gallstones. One Greek study found that frequent consumption of olive oil, which is rich in the unsaturated fat called oleic acid, was associated with a lower incidence of gallstones. And a 1995 study of Arabs in Gaza and Jews in Tel Aviv found that the Arabs consumed more unsaturated fats and had a lower incidence of gallstones.