Mechanisms of action of β-glucan in postprandial glucose metabolism in healthy men

Abstract

Objective: To assess whether b-glucan (which is fermented in the colon) lowers postprandial glucose concentrations through mechanisms distinct from a delayed carbohydrate absorption and inhibits de novo lipogenesis. Design: Administration of frequent small meals each hour over 9 h allows a rate of intestinal absorption to be reached which is independent of a delayed absorption. A group of 10 healthy men received either an isoenergetic diet containing 8.9 gaday b-glucan or without b-glucan for 3 days. On the third day, the diet was administered as fractioned meals ingested every hour for 9 h. Setting: Laboratory for human metabolic investigations. Subjects: Ten healthy male volunteers. Main outcome measures: Plasma glucose and insulin concentrations, glucose kinetics, glucose oxidation, de novo lipogenesis. Results: On the third day, plasma glucose and free fatty acid concentrations, carbohydrate and lipid oxidation, and energy expenditure were identical with b-glucan and cellulose. Plasma insulin concentrations were, however, 26% lower with b-glucan during the last 2 h of the 9 h meal ingestion. Glucose rate of appearance at steady state was 12% lower with b-glucan. This corresponded to a 21% reduction in the systemic appearance rate of exogenous carbohydrate with b-glucan, while endogenous glucose production was similar with both diets. De novo lipogenesis was similar with and without b-glucan. Conclusion: Administration of frequent meals with or without b-glucan results in similar carbohydrate and lipid metabolism. This suggests that the lowered postprandial glucose concentrations which are observed after ingestion of a single meal containing b-glucan are essentially due to a delayed and somewhat reduced carbohydrate absorption from the gut and do not result from the effects of fermentation products in the colon. Descriptors: glucose production; de novo lipogenesis; substrate oxidation

Potentiation of intestinal immunity by micellary mushroom extracts

“…In other words, phylogenetically developed lymphocytes (CD8αβ + , TCRαβ + ) were much more effectively activated by the oral administration of micellary β-glucan. These results suggest that smaller amounts of micellary β-glucan might be useful for the potentiation of intestinal immunity.It is empirically known that mushrooms, especially components of β-glucan, are good for our health (2,6,10,14,17,21) and sometimes show anti-tumor effects in animal models and humans (3,4,15). However, such anti-tumor effects of crude mushroom extracts were limited in our preliminary experiments.…”

“…Primarily, β-1,3-glucan is the major component of oats, mushrooms and yeasts (2,6,10,14,17,21). Since β-1,3-glucan is an indigestive sugar for humans, almost all of the large fragments of this sugar might be unabsorbed from the small intestine.…”

Muesli with 4 g oat β-glucans lowers glucose and insulin responses after a bread meal in healthy subjects

“…Thus, increasing the dose of b-glucans successively reduced the glucose response, which also was seen in the current study. The mechanism for a lowering postprandial glycaemia with b-glucans is probably related to an increased luminal viscosity, leading to a prolongation of carbohydrate digestion and absorption (Battilana et al, 2001). b-glucan is a source of viscous dietary fibre that preferably is found in oat and barley.…”

The effect of β-glucan on the glycemic and insulin index

“…The soluble fiber in oat, b-glucan, has been reported to modify the postprandial blood glucose responses by delaying the carbohydrate absorption (Anderson et al, 1990;Wood et al, 1994;Behall et al, 1998;Battilana et al, 2001). In addition to stabilizing glycemic responses, other positive health effects have been attributed to the b-glucans, including reduced plasma total and low-density lipoprotein (LDL)-cholesterol, weight management and improved gastrointestinal function.…”