Cholesterol absorption, elimination and synthesis in coeliac disease

Abstract

Hypocholesterolaemia and high faecal elimination of cholesterol was explored by measuring the percentage of cholesterol absorbed, faecal steroids, serum cholesterol and dietary cholesterol in patients with coeliac disease before and after a gluten free diet. From these data, the total and endogenous flux of cholesterol into the gut and the amount of cholesterol absorbed could be calculated. The mean faecal bile acid excretion was normal, but faecal endogenous steroids and thus faecal total steroids, and the cholesterol synthesis, were increased in the patients. The percentage of cholesterol absorbed was quite low (15.1 +/- 2.1 (SEM) v. 34.1 +/- 2.5 in the controls), and it was attributable to a mucosal damage in the upper small intestine, suggesting that this played a primary role in the high faecal sterol loss. However, the influx of endogenous cholesterol into the gut had increased, so that in absolute terms the absorption of cholesterol was low only inconsistently. The gluten-free diet caused the opposite changes in the absorption percentage and influx of cholesterol into the gut, while the amount of cholesterol absorbed was only insignificantly increased. Serum cholesterol was significantly correlated with the cholesterol absorbed (r = 0.36; P less than 0.01), faecal endogenous steroids (r = -0.30; P less than 0.05), and cholesterol synthesis (r = -0.29; P less than 0.05). Furthermore, the rise in serum cholesterol during the gluten-free diet correlated negatively with the changes in cholesterol (r = -0.55; P less than 0.05) and bile acid (r = -0.77; P less than 0.01) synthesis. These associations and the lack of correlations between the amounts of cholesterol absorbed and synthesized suggest that the serum cholesterol level and regulation of cholesterol synthesis are interrelated in coeliac disease.