Digestive physiological outcomes related to polydextrose and soluble maize fibre consumption by healthy adult men

The objective of the present study was to evaluate digestive physiological outcomes elicited by functional fibres fed to healthy adult men. A total of twenty-one healthy adult men were utilised in a cross-over design. Each subject received polydextrose (PDX) or soluble maize fibre (SCF) (21 g/d) or no supplemental fibre (no fibre control; NFC) in a snack bar. Periods were 21 d and faeces were collected during the last 5 d of each period. Food intake, including fibre intake, did not differ among treatments. Flatulence (P=0.001) and distention (P=0.07) were greatest when subjects consumed PDX or SCF. Reflux was greater (P=0.04) when subjects consumed SCF compared with NFC. All tolerance scores were low (<2.5), indicating only slight discomfort. Faecal ammonia, 4-methylphenol, indole and branched-chain fatty acid concentrations were decreased (P<0.01) when subjects consumed the functional fibre sources compared with NFC. Faecal acetate, propionate and butyrate concentrations were lower (P<0.05) when subjects consumed PDX compared with SCF and NFC. Faecal pH was lower (P=0.01) when subjects consumed SCF compared with NFC, while PDX was intermediate. Faecal wet weight was greatest (P=0.03) when subjects consumed SCF compared with NFC. Faecal dry weight tended to be greater (P=0.07) when subjects consumed PDX compared with NFC. The functional fibres led to 1.4 and 0.9 g (PDX and SCF, respectively) increases in faecal dry mass per g supplemental fibre intake. Bifidobacterium spp. concentrations were greater (P<0.05) when subjects consumed SCF compared with NFC. These functional fibres appear to be beneficial to gut health while leading to minimal gastrointestinal upset.