The prevalence of cholelithiasis is about 10 percent to 15 percent of the population of the U.S., or well over 25 million people. Nearly 1 million new cases of gallstone disease are diagnosed every year and approximately one quarter of these require treatment. The burden of cholelithiasis and its complications, such as cholecystitis, pancreatitis, and cholangitis, are major public health problems. A 2006 study reported that more than 700,000 cholecystectomies were performed in the United States at a cost of $6.5 billion dollars annually.[i]
Most patients are asymptomatic, but approximately 20% become symptomatic after 10 years of follow up.[ii] A study of both symptomatic and asymptomatic sonographically-confirmed cholelithiasis cases, found that the prevalence of gallstones was 1.9 time higher in non-vegetarians than in vegetarians.[iii]
This begs the question of which dietary factors are operational in the lower risk of cholelithiasis that vegetarians seem to experience. A study examining this question found that, although the prevalence of gallstone disease was less than half that of non-vegetarians, there was no difference in the intake of macronutrients between the study and control groups. In this cross-sectional study, the prevalence of gallbladder disease (asymptomatic gallstones or history of cholecystectomy) was significantly lower in vegetarians than omnivores (12% versus 25% p<0.01).[iv]
Another study, which looked not at total fat as in the above study, but saturated fat versus mono- and poly-unsaturated fat, found that after adjustment for age and other potential risk factors, compared with men in the lowest quintile of dietary intake of long-chain saturated fats, the relative risk of gallstone disease for men in the highest quintile was 1.24 (CI, 1.02, 1.50, P for trend = 0.03), and the relative risk of cholecystectomy for men in the highest quintile was 1.41 (CI, 1.09, 1.82, P for trend = 0.008). Medium-chain saturated fatty acids and short-chain saturated fatty acid intake was unrelated to the risk. Short-chain saturated fats are found in the colon as the result of microbial action on dietary fiber, medium-chain saturated fats occur naturally in plant foods, whereas long-chain fatty acids are primarily found in animal fats. This would therefore be another reason to prescribe a plant- based diet for the prevention of cholelithiasis.[v]
Complementing the above study was one that showed that polyunsaturated fats decrease the risk of gallstone formation. The relative risk for gallstone disease among men in the highest quintile of dietary intake of cis unsaturated fats, compared with men in the lowest quintile, was 0.82 (95% CI, 0.69 to 0.96; P for trend = 0.006) and the relative risk among men in the highest quintile of monounsaturated fat consumption compared with men in the lowest quintile was 0.83 (CI, 0.70 to 1.00; P for trend = 0.01) Again this contributes to the indication of a plant-based diet for the prophylaxis of cholelithiasis.[vi]
While the risk of cholelithiasis is lower in vegetarians, another study looked at the risk factors that remained amongst vegetarians themselves. Risk factors useful for predicting cholelithiasis in vegetarians are age and total bilirubin level in men, and age, BMI, and alcohol consumption in women. Many previously identified risk factors for the general population do not seem to apply to vegetarians. Just as interesting is some indication of what weren’t risk factors in this study. The study revealed that Diabetes Miletus, coronary artery disease, cerebral vascular accident, chronic renal failure, hepatitis C virus infection, and lipid abnormalities were not associated with cholelithiasis in male and female vegetarians. This finding may be explained by the protective effect of vegetarian diets according to the authors. [vii] Counseling patients already vegetarian should focus on modifiable risk factors, such as BMI and alcohol consumption, to reduce their risk still further.
Other research has focused on determining which dietary factors lower the risk of cholelithiasis among the general public. One study found that men consuming 5 or more ounces of tree nuts per week had a significantly lower risk of gallstone disease (relative risk = 0.70, 95% confidence interval: 0.60, 0.86; p(trend) < 0.001).[viii] In another study, those consuming the most fruits and vegetables were 21% less likely than those with the lowest intake to require cholecystectomy.[ix]
[i] Shaffer EA. Epidemiology of gallbladder stone disease. Best Pract Res Clin Gastroenterol 2006;20(6):981–996
[ii] Attili AF, De Santis A, Capri R, Repice AM, Maselli A. The natural history of gallstones: the GREPCO experience. The GREPCO Group. Hepatology 1995 Mar; 21(3):655–660.
[iii] Pixley F, Wilson D, McPherson K, Mann J. Effect of vegetarianism on development of gall stones in women. Br Med J (Clin Res Ed). 1985 Jul 6;291(6487):11-2.
[iv] Pixley F , Mann J Dietary factors in the aetiology of gall stones: a case control study. Gut. 1988 Nov;29(11):1511-5.
[v] Tsai CJ, Leitzmann MF, Willett WC, Giovannucci EL. Long-chain saturated fatty acids consumption and risk of gallstone disease among men. Ann Surg 2008;247:95-1
[vi] Tsai CJ, Leitzmann MF, Willett WC, Giovannucci EL. The effect of long-term intake of cis unsaturated fats on the risk for gallstone disease in men: a prospective cohort study. Ann Intern Med 2004;141:514-522
[vii] Chen Y-C, Chiou C, Lin M-N, Lin C-L (2014) The Prevalence and Risk Factors for Gallstone Disease in Taiwanese Vegetarians. PLoS ONE 9(12)
[viii] Chung-Jyi Tsai1, Michael F. Leitzmann et. al Frank B. Hu A prospective cohort study of nut consumption and the risk of gallstone disease in men. Am. J. Epidemiol. 2004;160 (10): 961-968.
[ix] Tsai CJ, Leitzmann MF, Willett WC, Giovannucci EL. Fruit and vegetable consumption and risk of cholecystectomy in women. Am J Med 2006;119:760-767