Breath-hydrogen production and amylose content of the diet

Recommendations to increase dietary intakes of starch and fiber in the United States may result in increased intake of resistant starch. High-amylose starch appears to resist digestion in vitro. To investigate the in vivo effect of high-amylose starch, diets containing 70% amylose or amylopectin cornstarches were fed for 14 wk each in a crossover design to 24 men [10 control, 14 hyperinsulinemic (HI)]. Fasting breath samples and periodic postingestion samples were analyzed for hydrogen during weeks 12 (nibbling tolerance test) and 14 (acute tolerance test) of each phase. Overall breath hydrogen was significantly higher after the amylose tolerance tests (nibbling, P < 0.0005; and acute, P < 0.0006). Control subjects, regardless of body mass index (BMI; in kg/m2), appeared to adapt to the high-amylose starch diet. Fasting breath hydrogen was significantly higher at week 12 but not at week 14 in HI subjects with a low BMI (< 25) consuming amylose than in other subjects. Breath hydrogen of the HI subjects with a moderate (between 25 and 27.8) or high (> 27.8) BMI increased from week 12 to week 14. The HI subjects with a high BMI averaged lower breath-hydrogen expiration than other HI subjects. After 3 d of excess energy intake, breath hydrogen after amylose was still significantly greater than after amylopectin (P < 0.019); fasting breath hydrogen of the control subjects after amylose more closely resembled that of the HI subjects. HI subjects with a high BMI may be more efficient at digesting all starch, therefore decreasing the amount available for colonic digestion. This may be a factor contributing to their greater body weight.