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, Hig h-amylose starch appears to resist digestion in vitro. To investigate the in vivo effect of high-amylose starch, diets containing 70% amylos e or amylopectin cornstarches were fed for 14 wk each in a crossover d esign 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 tes t) of each phase. Overall breath hydrogen was significantly higher aft er the amylose tolerance tests (nibbling, P < 0.0005; and acute, P < 0 .0006). Control subjects, regardless of body mass index (BMI; in kg/m( 2)), 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 subject s. 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 s ubjects 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 amy lose more closely resembled that of the HI subjects. HI subjects with a high BMI may be more efficient at digesting all starch, therefore de creasing the amount available for colonic digestion. This may be a fac tor contributing to their greater body weight.