DETERMINATION OF SUGAR ALCOHOL AND POLYDEXTROSE(R) ABSORPTION IN HUMANS BY THE BREATH HYDROGEN (H2) TECHNIQUE - THE STOICHIOMETRY OF HYDROGEN-PRODUCTION AND THE INTERACTION BETWEEN CARBOHYDRATES ASSESSED INVIVO AND INVITRO

The production of hydrogen from substrates and substrate mixture of su gar alcohols and Polydextrose(R) was determined, both in vivo using th e breath hydrogen test, and in vitro, using human faecal microorganism s in anaerobic culture. One objective was to test a previous assumptio n that the stoichiometry of hydrogen production from different alterna tive carbohydrates is similar. Another objective was to discover wheth er hydrogen responses from mixtures of substrates were simply additive , or whether interactions occurred. The breath tests were performed in a 10 subject X 10 substrate factorial design with substrates and subs trate mixtures (5-11 g) administered in 42 g chocolate confectionery. Incorporation of the alternative carbohydrates lactitol (L), Isomalt ( I) and Polydextrose(R) (P) into otherwise conventional confectionery i ncreased breath hydrogen production by approximately 112, 73 and 11%/g respectively. There was no interaction between L and I or between P a nd I, but a combination of L and P approximately doubled the breath hy drogen anticipated from their individual contributions (P < 0.05). Ana erobic cultures showed a sixfold range in the efficiency of converting individual substrates and mixtures to hydrogen gas (0.003-0.018 kJ H- 2 per kJ carbohydrate). The positive interaction between L and P, and the lack of interaction between L and 1, and between P and I, found in vivo were reproduced in vitro. The work showed that interpretation of the hydrogen breath test is confounded by differing stoichiometries f or hydrogen production, by interaction between substrates and by an un certain extent to which small intestinal hydrolysis yielding species w ith a fermentation stoichiometry that differs from the parent substrat e.