TUESDAY, Oct. 5, 2004 (HealthDayNews) -- Men who eat the kind of low-fat diet recommended to help prevent heart disease also reduce their risk of gallstones, a study finds.
The 14-year study of more than 45,000 men found that those who ate the most unsaturated fats -- the kind generally found in vegetables, rather than meat -- were 18 percent less likely to develop gallstones than men with the lowest unsaturated fat intake, according to the report, published in the Oct. 5 issue of the Annals of Internal Medicine.
"In animal experiments, dietary fats rich in unsaturated fats relative to saturated fats could protect against gallstone formation," said Dr. Chung-Jyi Tsai, an associate professor of medicine at the University of Kentucky and lead author of the report. "We tested the observation in this study."
The men in the study, all middle-aged or older, filled out a 131-question form about their eating habits in 1986, and again every two years after that. None of the men had been diagnosed as having gallstones at the start of the study. When they filled out their questionnaires over the next 14 years, they were repeatedly asked whether they had developed gallstones.
There was 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.
"There are a number of risk factors associated with gallstone formation," Tsai said, and the researchers checked for a number of them -- smoking, alcohol intake, physical activity and being overweight.
"Intake of unsaturated fats was independently related to gallstone occurrence," Tsai said.
There are several ways that fat intake can affect gallstone formation on the molecular level, the journal report said. For example, an increase in the amount of unsaturated fats in cell walls can make those cells more sensitive to insulin, which acts to reduce gallstone formation, the researchers wrote.
The trial results support those of smaller studies on the effect of fat intake on the risk of gallstones. One study in Greece found that high 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.
"Although the optimal amount of unsaturated fat intake is still unknown, our findings support the notion that, in dietary practice, a higher intake of unsaturated fats can confer health benefits," the researchers wrote.
Asked whether the finding supports the current dietary recommendations of the American Heart Association and other heart-conscious organizations, Tsai replied, simply, "Yes."
Learn about the association between diet and gallstones from the National Institute of Diabetes and Digestive and Kidney Diseases.