DIGESTIVE AND METABOLIC EFFECTS OF POTATO AND MAIZE FIBERS IN HUMAN-SUBJECTS

The physiological effects of dietary fibres in humans are due to their physico-chemical properties. However, it is difficult to predict thes e effects simply by measuring certain characteristics in vitro. Studie s in human subjects are still required to assess the effectiveness of new substrates. The aim of the present study in healthy human subjects was to evaluate the effects of two novel fibres, potato (PF) and maiz e (MF), on fasting and postprandial blood concentrations of carbohydra te and lipid metabolites as well as on stool ouput and transit time. T he chemical composition, water-binding capacity (WBC) and fermentative properties of the fibres were also characterized in order to determin e their possible involvement in digestive and metabolic effects. Stool s, as well as breath and blood samples, were collected after consumpti on for 1 month of either a basal diet (control) or a basal diet supple mented with fibre (15 g/d). MF resisted fermentation better than PF an d had lower digestibility. However, both fibres increased faecal outpu t of dry matter, neutral sugars and water. There was an inverse relati onship between stool weight and orofaecal transit time, although only MF significantly reduced transit time. Orocaecal transit was lengthene d by PF, probably because of its high WBC. PF ingestion also decreased postprandial plasma levels of total and esterified cholesterol but ha d no effect on fasting concentrations. In contrast, MF lowered fasting cholesterolaemia and increased free:esterified cholesterol. These par ticular physiological and fermentative properties suggest that PF and MF would be suitable ingredients in a healthy diet.