Effects of a commercial starch blocker preparation on carbohydrate digestion and absorption: in vivo and in vitro studies

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Abstract
We have tested the effectiveness of a commercial starch blocker on the digestion and absorption of dietary carbohydrates in six normal, healthy volunteers. The effectiveness of the starch blocker to attenuate or block the digestion of carbohydrate was assessed against a placebo by the measurement of end tidal breath hydrogen, plasma glucose, and insulin responses to a constant test meal. There were no significant differences in breath hydrogen, or plasma glucose and insulin responses. In vitro enzyme inhibition studies assessed the ability of the brush border enzyme maltase/glucoamylase to degrade starch in the presence of the starch blockers. A highly purified solution of rat and human maltase/glucoamylase was capable of degrading a starch solution, while 40 mM Tris-HCl (a known maltase/glucoamylase inhibitor) completely abolished the enzyme activity. These data challenge the claims that starch blocker preparations are effective in reducing or attenuating the absorption of carbohydrates or calories from a mixed meal. The ineffectiveness in vivo could be explained, in part, by the ability of the brush border enzyme maltase/glucoamylase to hydrolyze starch in the presence of starch blockers.