OBJECTIVE: To investigate the effects of inulin and oligofructose on cholesterol absorption and excretion of cholesterol, bile acids, energy, nitrogen and minerals in man.

DESIGN: Double-blind cross-over study.

SETTING: Metabolic kitchen with policlinic visits, Sahlgrenska Hospital, Göteborg, Sweden

SUBJECTS: Patients with conventional ileostomy because of ulcerative colitis.

INTERVENTIONS: 17 g of inulin, 17 g of oligofructose and 7 g of sucrose were added to a controlled diet during three experimental periods of three days each. Ileostomy effluents were collected and analysed. Differences between experimental and control diet were investigated with the Wilcoxon’s sign and values test.

RESULTS: Inulin and oligofructose were recovered in the ileostomy effluent to 88%(95% CI, 76–100%) and 89%(64–114%) respectively. Dry solid excretion increased by 14.4 g (11.3–17.5) on inulin, and by 14.7 g (13.0–16.4 g) on oligofructose and energy excretion increased 245 kJ (190–307 kJ) on inulin and 230 kJ (217–315 kJ) on oligofructose compared to control diet (P< 0.05). Cholesterol absorption, excretion of cholesterol, bile acids, nitrogen, fat, calcium, magnesium, zinc and iron were not affected by inulin and oligofructose.

CONCLUSIONS: Inulin and oligofructose are not digested in the small intestine. They do not affect mineral excretion and hence hardly mineral absorption. They do not increase fat or nitrogen excretion from the small intestine. Any physiological effect of inulin and oligofructose is probably mediated through other mechanisms than altered excretion from the small intestine.