Objective: To determine the tolerance of increasing dosages of an incompletely hydrolysed and/or incompletely absorbed food dextrin coming from wheat starch, NUTRIOSE� FB, at daily levels of 10 and 15 g up to 60 and 80 g, respectively.

Design: A randomized, double-blind, multiple dose, placebo-controlled, combined crossover and parallel trial.

Setting: The metabolic ward of TNO Nutrition and Food Research.

Subjects: A total of 20 healthy men (age 31.7�9.1 y; BMI 24.5�2.9 kg/m 2).

Intervention: One group of 10 subjects consumed on top of their diet 10, 30 and 60 g of NUTRIOSE� FB or maltodextrin (placebo) daily. The other group of 10 subjects consumed 15, 45 and 80 g daily. Each dose was consumed for 7 days.

Results: Compared with placebo, flatulence occurred more frequently over the last 6 days on 30, 60 or 80 g/day of NUTRIOSE� FB (P< 0.05). During the last 24 h, that is, days 6–7, of 60 and 80 g/day of NUTRIOSE� FB, the frequency of flatulence was even higher (P< 0.05). During the last 24 h on a daily dose of 60 g NUTRIOSE� FB, the frequency of defecation decreased (P< 0.05). Bloating occurred more often during the last 24 h on 80 g/day of NUTRIOSE� FB (P< 0.05). None of the doses of NUTRIOSE� FB resulted in diarrhoea. Compared to baseline levels, breath H 2 excretion, which was only measured after a week with 10 and 15 g of NUTRIOSE� FB daily, increased (P< 0.05). However, no difference in area under the curve was found.

Conclusions: NUTRIOSE� FB is a fermentable carbohydrate and is well tolerated up to a dose of 45 g daily. Higher daily dosages (60 and 80 g) may result in flatulence, but does not result in diarrhoea.