Mixed-linked beta-glucan from breads of different cereals is partly degraded in the human ileostomy model

The purpose of this investigation was to study the degradation of beta-glucan in the small intestine and the molecular weight of beta-glucan in the excreta of nine ileostomy subjects after consumption of different diets based on bread made with oat bran (oat bread), a fiber-rich barley fraction (barley bread), or wheat flour (wheat bread) as the main ingredients. Oat bread with enzymatically degraded beta-glucan was also used (oat + enzyme bread). The beta-glucan intake from the four diets was 12.5, 12.9, 1.1, and 4.0 g/d, respectively. On the basis of dry matter, the night effluents accounted for approximately 15% of the total amount of the excreta, with the highest proportion (22%) being for the wheat-bread diet. A notable loss of beta-glucan (0.7-2.4 g/d, or 13-64%) was found when intake was compared with excretion. In vitro, a higher viscosity development with time for dispersions of oat bread compared with barley bread was noted, which could be related to the higher molecular weight of the beta-glucan in this bread. There seemed to be a depolymerization of the beta-glucan both during bread making and transit through the upper gastrointestinal tract.