EFFECTS OF LOW-FAT MILK AND FERMENTED LOW-FAT MILK ON CHOLESTEROL ABSORPTION AND EXCRETION IN ILEOSTOMY SUBJECTS

Objective: To study small bowel cholesterol absorption and sterol excr etion in order to explain possible serum cholesterol-lowering mechanis ms of low-fat milk products. Design: Two 24-h sterol balance studies w ith 1 litre of low-fat milk or one litre of fermented milk, in random order, added to a controlled diet. [H-3]Cholesterol absorption was mea sured during each period. The results were compared to those on two 24 -h periods with isocaloric amounts of lemonade given to the same basic diet, before and after the study. One litre of the two milk products was also consumed in addition to their normal diets in a cross-over de sign of 3 weeks and with run-in and run-out periods of 2 weeks each wi th 1000 ml of lemonade preceding the balance studies. Setting: Outpati ent clinic, where the subjects were eating their meals during the day and ileostomy bags collected. Subjects: Nine ileostomy subjects, who h ave earlier participated in similar studies, volunteered for the study . All subjects completed the study. Results: Cholesterol absorption wa s highest (66%) in the lemonade period, intermediate in the low-fat mi lk period (61%) and lowest in the fermented low-fat period (55%) (P < 0.05 for differences). Net cholesterol excretion (excretion minus inta ke) and calculated endogenous cholesterol excretion were significantly (P < 0.05 for differences) higher in the low-fat milk period than in the lemonade period and the fermented low-fat milk period. No signific ant change in serum cholesterol was, however, seen after 3 weeks on ea ch milk regimen. Conclusion: Assimilation of cholesterol by microorgan isms could possibly explain the reduced uptake of cholesterol with fer mented milk. The mechanism behind the increased endogenous cholesterol excretion, induced by low-fat milk, is unclear. Sponsorship: Swedish Council for Forestry and Agricultural Research and the Norrland Dairy Industries.