A combined 13CO2/H2 breath test can be used to assess starch digestion and fermentation in humans

Ingestion of starch from corn (naturally enriched with C-13) should produce (CO2)-C-13 after small intestinal digestion and (CO2)-C-13 and H-2 from colonic fermentation. This study used a combined (CO2)-C-13/H-2 breath test to assess the digestion and fermentation of resistant starch and to show that the test could detect changes in digestibility due to cooking. Volunteers consumed 40 g digestible cornstarch with water (n = 8), or 40 g resistant cornstarch in liquid (n = 12) or cooked into a pancake (n = 4). Interval breath sampling was performed and analyzed for (CO2)-C-13 and H-2. Ingestion of resistant starch produced a double-peaked (CO2)-C-13 excretion curve. The first increase in (CO2)-C-13 occurred at the same time as excretion from digestible starch (55 +/- 9 and 68 +/- 9 min, respectively), which was due to small intestinal digestion. The second increase in 13CO2 was accompanied by an increase in H2 excretion (432 +/- 15 and 428 48 min, respectively), which was indicative of colonic bacterial fermentation. Cooking resistant starch increased its degree of digestion from 36 to 72%. The (CO2)-C-13/H-2 breath test can be used to estimate digestion and fermentation of starches in different physiologic and pathologic conditions.