Cholelithiasis: Nutritional Considerations
Gallstones are strongly related to a high-fat, low-fiber diet. They are uncommon in Asian and African populations following traditional, largely plant-based, diets, and become more common with a shift toward Westernized diets.1 A surplus of animal protein and animal fat, a lack of dietary fiber, and eating fat from saturated rather than unsaturated sources appear to be the main factors for gallstone development. The following factors are associated with reduced risk of gallstones:
Plant-based diets. Both animal fat and animal protein may contribute to the formation of gallstones. In most Western populations, an estimated 80% of gallstones are cholesterol stones,2 suggesting the value of reducing saturated fat and cholesterol in the diet.
Not surprisingly, vegetarian women have a much lower risk for gallstones, compared with nonvegetarian women.3 Vegetarian diets are high in fiber, and whatever fat they contain is largely unsaturated. Vitamin C, another nutrient found in higher amounts in vegetarian diets, affects the rate-limiting step in the catabolism of cholesterol to bile acids and is inversely related to the risk of gallstones in women.4
Women consuming the most vegetable protein had a 20% to 30% lower risk than those consuming the least.5,6 Similarly, women and men whose fat intake comes primarily from plant sources have a reduced risk of developing gallstones.7 An exception is trans fatty acids—the partially hydrogenated vegetable oils often used in snack foods—which are associated with increased gallstone risk.8
Replacement of sugars and refined starches with high-fiber carbohydrates. The cholesterol saturation index of bile, a known risk factor for gallstone formation,9 is higher with diets that provide carbohydrates in a refined, as opposed to unrefined, form.10 Individuals consuming the most refined carbohydrates had a 60% greater risk for developing gallstones, compared with those who consumed the least.11 Conversely, individuals eating the most fiber (particularly insoluble fiber) have a 15% lower risk for gallstones compared with those eating the least.12,13
Avoidance of overweight and a healthful approach to weight control. Overweight women with a BMI of 30 kg/m2 or more have at least double the risk for gallstone disease, compared with women of normal weight (BMI < than 25 kg/m2). The same degree of risk exists for men with a BMI of at least 25 kg/m2, compared with males with a BMI of <22.5 kg/m2. With more severe obesity (ie, BMI 30 to 45 kg/m2), the risk for women is 3.7 to 7.4 times that of women with a BMI of less than 24 kg/m2.14
Weight cycling (repeatedly losing and regaining weight) increases the likelihood of cholelithiasis. The risk increased from 20% in "light" cyclers (those who lost/regained 5 to 9 lbs) to 70% in "severe" cyclers (those who lost/regained >20 lbs).15
Very-low-calorie diets increase the risk of gallstones. Gallbladder stasis and bile cholesterol saturation index occur during rapid weight loss, accounting for a greater risk of gallstone development. Including a small amount of fat (10 g/day) provides maximal gallbladder emptying and prevents gallstone formation in calorie-restricted dieters.16 Such observations support weight control efforts based on low-fat, plant-based diets, which typically cause healthful and sustained weight control, rather than the use of very-low-calorie formula diets.
Moderate alcohol intake. Compared with infrequent consumption or abstinence, moderate alcohol intake was found to be either inversely associated with the risk for gallstones,17 or to confer a 10% to 50% lower risk for the disease.18 However, given the current epidemic of nonalcoholic fatty liver disease in 50% to 75% of obese persons19 and other health risks (eg, breast cancer) due to alcohol consumption, alcohol use cannot be recommended as a gallstone prevention strategy.
Physical activity. Some evidence suggests that physical activity reduces gallstone risk. Young or middle-aged men (65 years or younger) who were the most physically active had half the risk for developing gallstones, compared with those who were least active. In older men, physical activity cut risk by 25%.20 Physical activity also protects against gallstones in women.21
What to Tell the Family
Gallstones can largely be avoided by following a high-fiber diet, particularly a vegetarian diet. Patients should avoid foods high in saturated fat (eg, animal products) and trans-unsaturated fat (eg, processed foods). Foods high in polyunsaturated fat (eg, nuts and other vegetable sources) may reduce risk.
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