Measurement of water-holding properties of fibre and their faecal bulking ability in man.

Experiments to measure the effect of a fibre source in the diet on stool bulk are difficult and lack precision. In vitro methods which would identify fibre sources that are effective for clinical and epidemiologic use would be valuable. One important property of fibre which influences the ability of fibre to increase stool weight is its water-holding capacity (WHC). WHC was measured using centrifugation, filtration, suction pressure and water flow-rate techniques using fibre concentrates of potato, cereal bran and gum arabic. Dietary supplementation of three preparations of potato fibre (20 g/d) had no significant effect on stool weight but 16 g bran/d increased stool weight from 107 (SE 44) g/d to 174 (SE 51) g/d. The effects of these fibres on stool weight can be related to the nature of the water-holding properties of fibre rather than absolute WHC.