Effects of short-chain fructo-oligosaccharides on glucose and lipid metabolism in mild hypercholesterolaemic individuals

Background: The intake of 10 g/day of short-chain-fructo-oligosaccharides (sc-FOS) has been shown to increase significantly bifidus counts and to produce high amounts of short-chain fatty acids (SCFA), presumed to influence glucose and lipid metabolism. Aim: To evaluate the effects of moderate intake of sc-FOS on glucose and lipid metabolism in individuals with mild hypercholesterolaemia. Design: A randomized double-blind sequential cross-over study. Subjects and methods: Thirty subjects of both genders (20 M/10 F), mean age 45.5±9.9 years (M±SD), BMI 26.6±2.2 kg/m2, with plasma cholesterol >5.17 and <7.76 mmol/l and plasma triglycerides <3.45 mmol/l, participated in the study. The study was performed after a wash-out period of 1 month and a run-in period of 1 month to stabilize patients on a standard diet (CHO 50%, fat 30%, protein 20%, fibre 20 g/day) plus placebo (maltodextrine plus aspartame 15 g/day). At the end of run-in, subjects were randomly assigned to receive sc-FOS (Actilight(R)) (10.6 g/day) or placebo (maltodextrine plus aspartame 15 g/day) with tea and/or coffee for a duration of 2 months and thereafter switched to the other treatment for additional 2 months. Plasma glucose, total and lipoprotein (VLDL, LDL, HDL) cholesterol and triglyceride concentrations were measured in the fasting state at the end of run-in and of each treatment period. At the end of the two treatment periods, patients consumed a standard test meal (protein 15%, carbohydrate 34%, fat 51%, kJ 3988) 1 h after the administration of 5.3 g of sc-FOS or placebo; plasma glucose, insulin, free fatty acid (FFA) and triglyceride responses to the test meal were evaluated. Results: No significant difference in fasting parameters was detected between the two treatments. After sc-FOS and placebo plasma cholesterol levels were, respectively, 6.47±0.70 and 6.44±0.78 mmol/l (n.s.) and plasma triglycerides were 1.53±0.71 and 1.56±0.53 mmol/l (n.s.). No significant differences were observed in cholesterol and triglyceride content of VLDL, LDL and HDL and in plasma Apo A1 levels; conversely, fasting plasma Lp(a) concentrations were significantly increased after sc-FOS (37±38 vs. 33±35 mg/dl; P<0.005). Postprandial responses of glucose, FFA and triglycerides were not significantly different between sc-FOS and placebo, while postprandial insulin response (incremental area) was significantly reduced after sc-FOS compared to placebo (14 490±7416 vs. 17 760±7710 pmol/l × 300 min; P<0.02). Conclusions: A moderate intake of sc-FOS has no major effects on lipid metabolism, both in the fasting and in the postprandial period, in individuals with mild hypercholesterolaemia. A small but significant increase of Lp(a) concentrations was observed with sc-FOS consumption together with a reduction of the postprandial insulin response; however, the clinical relevance of these small effects is unclear.