HONOLULU — Liberal consumption of foods with a high glycemic index increases the risk of cholecystectomy in women, Dr. Chung-Jyi Tsai reported at the annual meeting of the American College of Gastroenterology.
“Our findings suggest that not all carbohydrates are equivalent,” said Dr. Tsai of the University of Kentucky, Lexington.
Gallstone disease affects 10%–25% of American adults and is a leading cause of hospital admission. More than 800,000 cholecystectomies are performed in the United States annually.
In this country and other parts of the developed world, most gallstones are cholesterol stones. Research has shown that high carbohydrate consumption can lead to elevated triglycerides and low HDL cholesterol levels, along with visceral adiposity. This metabolic pattern, often seen in conjunction with insulin resistance, is believed to promote secretion of cholesterol into the bile and has been associated with increased risk of gallstone disease, Dr. Tsai explained.
He turned to the Nurses' Health Study to test his hypothesis that heavy consumption of foods with a high glycemic index—that is, foods that trigger a relatively robust glycemic response—increases the risk of symptomatic gallstone disease leading to cholecystectomy.
The Nurses' Health Study began in 1976 and involves prospective collection of medical, lifestyle, and food frequency data every several years from more than 120,000 American nurses. Because the participants are interested health professionals, follow-up rates are extremely high. And since the data are collected well before disease end points occur, the potential for research bias is minimized, the gastroenterologist noted.
Dr. Tsai reported on 70,408 women who participated in the study during 1984–2000. During 932,676 person-years of follow-up, 5,771 women underwent cholecystectomy.
From the participants' detailed food consumption records, investigators calculated each woman's average glycemic index. This was derived by multiplying the carbohydrate content of each serving of food they ate by the average number of servings of that food per day times the food's glycemic index, summing the products, and then dividing this figure by the total daily carbohydrate intake.
In a multivariate analysis that adjusted for the known risk factors for symptomatic gallstone disease, women in the top quintile for glycemic index had a highly significant 32% greater risk of undergoing cholecystectomy, compared with women in the lowest quintile.
A similar pattern was noted with regard to glycemic load. A woman's glycemic load was calculated by multiplying the carbohydrate content of each food she consumed by its glycemic index, then multiplying this figure by the food's frequency of consumption, and finally summing these values for all foods.