Consumption of both resistant starch and beta-glucan improves postprandial plasma glucose and insulin in women.

OBJECTIVE: Consumption of a meal high in resistant starch or soluble fiber (beta-glucan) decreases peak insulin and glucose concentrations and areas under the curve (AUCs). The objective was to determine whether the effects of soluble fiber and resistant starch on glycemic variables are additive. RESEARCH DESIGN AND METHODS: Ten normal-weight (43.5 years of age, BMI 22.0 kg/m2) and 10 overweight women (43.3 years of age, BMI 30.4 kg/m2) consumed 10 tolerance meals in a Latin square design. Meals (1 g carbohydrate/kg body wt) were glucose alone or muffins made with different levels of soluble fiber (0.26, 0.68, or 2.3 g beta-glucan/100 g muffin) and three levels of resistant starch (0.71, 2.57, or 5.06 g/100 g muffin). RESULTS: Overweight subjects had plasma insulin concentrations higher than those of normal-weight subjects but maintained similar plasma glucose levels. Compared with low beta-glucan-low resistant starch muffins, glucose and insulin AUC decreased when beta-glucan (17 and 33%, respectively) or resistant starch (24 and 38%, respectively) content was increased. The greatest AUC reduction occurred after meals containing both high beta-glucan-high resistant starch (33 and 59% lower AUC for glucose and insulin, respectively). Overweight women were somewhat more insulin resistant than control women. CONCLUSIONS: Soluble fiber appears to have a greater effect on postprandial insulin response while glucose reduction is greater after resistant starch from high-amylose cornstarch. The reduction in glycemic response was enhanced by combining resistant starch and soluble fiber. Consumption of foods containing moderate amounts of these fibers may improve glucose metabolism in both normal and overweight women.

Barley bread containing lactic acid improves glucose tolerance at a subsequent meal in healthy men and women.

In the present study, we evaluated whether a low glycemic index (GI) breakfast with lactic acid bread had an effect on glucose tolerance and insulinemia at a subsequent high GI lunch meal. A barley bread containing lactic acid and a reference barley bread were consumed in the morning after an overnight fast in random order by 10 healthy men and women. Four hours after the breakfasts, the subjects ate a standardized high GI lunch, and the blood glucose and insulin responses were measured for the next 3 h. Significant lowerings of the incremental glycemic area (-23%, P = 0.033) and of the glucose response at 95 min were found after the lunch meal when the barley bread with lactic acid was given as a breakfast. At 45 min after the lunch meal, the insulin level was significantly lower (-21%, P = 0.045) after the lactic acid bread breakfast, compared with the barley bread breakfast without lactic acid. We concluded that barley bread containing lactic acid eaten at breakfast has the potential to improve second-meal glucose tolerance at a high GI lunch meal 4 h later.