Dietary fiber effects on passage rate and breath hydrogen.pdf

44 Dietary fiber effects on passage rate and breath hydrogen13 Christa F Hanson, PhD and Esther A Winterfeldt, RD, PhD ABSTRAC1’ Fermentation of fiber and passage to the large intestine were monitored by measuring hydrogen gas (H2) concentration in expired breath. Five subjects consumed meals containing no added fiber or 40 g of wheat bran (WB), corn bran (CB), oat bran (OB), or citrus flour (CF) replacing white flour. Breath samples were obtained at 30 mm intervals for 9 h after the test meals. Mean H2 concentration (ppm), averaged over the 9 h test period, ranged from 7.5 (CB) to 12.0 (OB) and tended to increase with addition of OB, CF, or WB but decrease with addition of CB. Hours from the meal to the highest H2 peaks were 4.7 (WB), 5.6 (CB), 6.2 (OB), 6.4 (CF), and 8.2 (basal). The gel-like fibers (OB and CF) resulted in greater H2 concentration and less acceleration of passage rate than the particulate fibers (WB and CB). Am J C/in Nuir 1985;42:44-48. KEY WORDS Breath hydrogen, fiber, passage time, wheat bran, corn bran, citrus flour, oat bran Introduction Epidemiological studies have indicated that the consumption of dietary fiber may prevent various degenerative diseases common to Western countries (1, 2). Dietary fibers differ in physical and chemical characteristics, as well as in their effects on the gastrointestinal tract (3); interactions between intestinal bac- teria and fiber may have additional effects (4, 5). When fiber is fermented in the lower intestine, bacteria produce hydrogen gas, methane, and short chain fatty acids. Hydro- gen gas is partially absorbed and excreted through the lungs (6). Hydrogen gas produc- ing organisms, which ferment various fiber fractions, have been identified in the human intestinal tract (7). Bacterial fermentation of fiber alters the concentration of hydrogen in breath, and fiber consumption changes passage time through the gastrointestinal tract. In subjects fed single doses of purified fibers in flavored water, brea