Digestive tolerance of inulin-type fructans: a double-blind, placebo-controlled, cross-over, dose-ranging, randomized study in healthy volunteers

Background Similar to other indigestible carbohydrates or dietary fibres, a consumption of too large quantities of inulin-type fructans may cause some digestive problems. Aim To compare the digestive tolerance of inulin-type fructans, administered during 2 weeks, at different doses. Methods Eighty-four healthy volunteers (aged 18-45 years, mean body mass index 25.1 kg/m2 and mean total fibre consumption 12 g) were included in a double-blind, placebo-controlled, randomized, cross-over study comparing Fibrulose F97 (5 and 20 g/day), Fibruline Instant (5, 10 and 20 g/day) and Fibruline XL (10 g/day) (degrees of polymerization respectively equal to 2-20, 2-60 with an average of 10, and 2-60 with an average 20) to placebo. The study was decomposed into five 2-week periods: placebo run-in, treatment 1, placebo washout, treatment 2, placebo run-out. The following symptoms were assessed using visual analogue scales: flatulence, rumbling, bloating, abdominal pain, abdominal cramps, nausea, stool frequency and stool consistency. The primary variable was the mean difference between treatment and placebo in terms of tolerance (sum of the eight visual analogue scales). Results The three products tended to increase digestive symptoms whatever the dose but the change was mild (maximum, +19 mm on the 800-mm scale) and significant (P0.001) for Fibruline Instant at 20 g/day only. At 20 g/day, a statistically significant difference between Fibruline Instant and Fibrulose F97 was demonstrated (P=0.011). There was a dose-effect relationship both for Fibrulose F97 (P0.05) and Fibruline Instant (P=0.042). All the other tendencies were non-significant. Conclusions The three different inulin-type fructans were very well tolerated.