Fermentation of the carbohydrate of banana (Paradisiaca sapientum) in the human large intestine.

Fermentation of dietary fiber and resistant starch is one of the major physiological functions of the human large intestine. The major substrate for fermentation is probably starch. This study assessed the effect of bananas--a carbohydrate with a highly resistant starch content--on breath hydrogen and methane production in methane and nonmethane-producing subjects. The results showed that both groups produced significant quantities of hydrogen after a banana meal, compared with a sucrose control test meal, measured as area under the curve (28 +/- 5.6 vs. 8.1 +/- 1.4 10(3) pm/min, p = 0.008 in methane producers and 39 +/- 15.2 vs. 10.5 +/- 4.1 10(3) ppm/min, p = 0.01 in methane nonproducers). The rise in breath hydrogen started a half hour after the banana meal and peaked at 3 1/2 h in methane nonproducers, whereas in methane producers, the rise began after 2 h and peaked at 5 h. Methane production was not significantly stimulated by the test meals. This study shows that bananas stimulate fermentation mainly through the production of hydrogen, with minimal effect on methane production. The possible mechanisms for this process are discussed.