Will recommended changes in fat and fibre intake affect cholesterol absorption and sterol excretion? An ileostomy study

Abstract

Objective: To study cholesterol absorption and excretion in ileostomy subjects with different intakes of saturated fat and dietary fibre.

Design: Short-term experimental study, with four controlled diets in repeated measurements.

Setting: Out-patients at metabolic-ward kitchen.

Subjects: Nine healthy volunteers with conventional ileostomy after colectomy because of ulcerative colitis.

Interventions: Four diet periods, each of 3 days duration: high saturated fat and low dietary fibre (STAND); reduced saturated fat (RESAT); high saturated fat and high fibre (FATFIB); and reduced saturated fat and high fibre (RESATFIB).

Main outcome measures: Absorption of cholesterol, and ileal excretion of cholesterol, bile acids, fat and energy. Differences between diets evaluated with Friedman’s two-way analysis of variance by rank sum with Bonferroni adjustment, and post hoc differences assessed by rank sum comparison.

Results: RESAT and RESATFIB reduced fractional cholesterol absorption by 7% and 10%; RESATFIB and FATFIB increased net cholesterol excretion by 46% and 54% respectively. Further, RESATFIB increased net sterol excretion by 18%, all compared to STAND (P<0.05 for all). All three intervention diets contained more phytosterols than STAND (P<0.05), and the phytosterol content was inversely correlated to fractional cholesterol absorption (r=−0.77, P<0.01).

Conclusions: Current nutrition recommendations to reduce saturated fat and increase dietary fibre affect sterol excretion additively. The effect on cholesterol absorption might be partly explained by the content of dietary plant sterols.

Sponsorship: Supported by grants from the Gothenburg Medical Society, grant numbers 94/086 and 99/082, and by the University of Gothenburg.

European Journal of Clinical Nutrition (2000) 54, 306–313