New York - Women who regularly eat fruits and vegetables may have lower odds of developing painful gallstones, the results of a large study suggest.
Of more than 77 000 US women in the long-running Nurses' Health Study, researchers found that those who ate the most fruits and vegetables were less likely to require surgery to remove their gallbladder.
Usually, this surgery is performed because of gallstones, masses that develop when bile stored in the gallbladder hardens into pieces of stone-like material. These "gallstones" may cause no symptoms, pass through the intestine, or result in severe pain, block the bile ducts, cause infection, or can even be fatal.
The findings suggest that a diet rich in fruits and vegetables - particularly leafy greens, citrus fruits and other vitamin-C-rich foods - can prevent gallstones from forming or from causing symptoms, Dr Chung-Jyi Tsai at Harvard Medical School in Boston and colleagues report in the American Journal of Medicine.
The results are based on data from 77 090 female nurses who, in 1984, were between the ages of 37 and 64. They answered dietary questionnaires that year, and had the rates of gallbladder removal called cholecystectomy - were followed through 2000.
Cholecystectomy is the most common treatment for symptomatic gallstones; stones that do not cause symptoms are generally left untreated. So rates of cholecystectomy are indicative of the rate of painful gallstones.
During the study period, Tsai's team found, roughly 6 600 women had their gallbladders removed. But those with the highest intake of fruits and vegetables at the study's start were 21 percent less likely than those with the lowest intake to have the surgery.
The risk reduction was independent of other factors that increase the risk of gallstone formation, such as age, weight and diabetes.
Women in the group with highest intake of fruits and vegetables typically ate seven or more servings a day; those with the lowest intake generally ate less than three servings.
Citrus fruits, leafy green vegetables, and all foods rich in vitamin C seemed to be particularly protective, the study found. According to the researchers, dietary fibre, antioxidant vitamins - which include vitamin C - and minerals such as magnesium may all theoretically help prevent symptomatic gallstones.
However, they add, the benefit is likely due to a complex interaction of nutrients.
"Because any single constituent in fruits and vegetables is unlikely to explain fully the beneficial effect," Tsai's team writes, "it is reasonable and practical to recommend an abundant fruit and vegetable consumption."
SOURCE: American Journal of Medicine, September 2006.