Barley β-glucan reduces plasma glucose and insulin responses compared with resistant starch in men

Glucose and insulin responses have been reported to be lowered by acute consumption of soluble oat fiber or high amylose cornstarch. This study sought to determine if barley β-glucan and preformed resistant starch reduced glucose and insulin responses in men independently or if a synergism exists between the two carbohydrate sources. A total of 20 men (10 control, 10 overweight; average body mass index, 23.8 vs 29.0) were fed a controlled diet for 2 days before each treatment containing 75 g available carbohydrate. Fasting subjects consumed 10 treatments consisting of glucose or 1 of 9 muffins containing 3 levels of resistant starch (0.1, 6.1, or 11.6 g/tolerance) and 3 levels of β-glucan (0.1, 3.1, or 5.8 g/tolerance) in a Latin square design. Plasma glucose and insulin responses were determined over 4 hours after each treatment. Compared with controls, overweight subjects had significantly higher mean glucose (5.5 vs 6.0 ± 0.1 mmol/L) (P < .003) and insulin (153 vs 285 ± 21 mmol/L) (P < .0001) concentrations. Glucose (P < .001) and insulin (P < .003) responses were lower and returned to fasting quicker in the controls than in overweight subjects. The highest β-glucan level was the most effective in lowering glucose (P < .001) and insulin responses (P < .0001). Average glucose (P < .025) and insulin (P < .0001) areas under the curve were lowest after the muffins containing the high β-glucan. Resistant starch content was less effective than β-glucan in reducing glucose or insulin response. Acute consumption of barley β-glucan, but not resistant starch, in muffins was effective in reducing glucose and insulin responses in men who were mildly insulin-resistant.