Lathosterol and other non-cholesterol sterols during treatment of hypercholesterolaemia with beta-glucan-rich oat bran

Objective and subjects: Dietary fibre has been suggested to interfere with endogenous cholesterol synthesis in the liver. Therefore the effects of oat bran on the proportions of cholesterol synthesis precursors (squalene, Delta(8)-cholestenol, desmosterol and lathosterol), cholestanol and plant sterols (campesterol and beta-sitosterol) to cholesterol were analysed in serum of 36 hypercholesterolaemic subjects. Design: A randomized study of eight weeks duration where beta-glucan-rich oat bran (n = 20, subjects) or wheat bran (n = 16) was used as a part of a cholesterol lowering diet. Plant sterols and cholesterol synthesis precursors were analysed from frozen samples afterward. Results: In the oat-bran group, but not in the wheat bran group, serum total cholesterol declined transiently. The proportions of plant sterols and cholestanol in serum, which reflect cholesterol absorption efficiency were unchanged. However, the proportions of squalene appeared to be transiently increased during the study. Subjects with apolipoprotein E 4 allele had higher serum campesterol and sitosterol levels (suggestive of efficient cholesterol absorption) than those with homozygous apolipoprotein E 3 allele. Conclusions: Since the cholesterol precursors in serum reflecting endogenous cholesterol synthesis remained almost unchanged the reduction in the serum cholesterol level by oat bran treatment can not be ascribed to an inhibition of the endogenous cholesterol synthesis.