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1、Excretion of Breath and Flatus Gases by HumansConsuming High-Fiber Diets1DIANA MARTHINSEN ANDS. E. FLEMINGDepartment of Nutritional Sciences, University of California,Berkeley, CA 94720ABSTRACT The abilities of dietary fibers to promote the excretion of intestinalfermentation gases were evaluated in
2、 five healthy men. Flatus and breath gases werecollected and analyzed during 3 days of each 9-day metabolic period. Responses tofeeding xylan, pectin, cellulose and corn bran were compared to a fiber-free formuladiet. Generally, hydrogen production increased throughout the day, whereas methaneproduc
3、tion remained more constant. Methane excretion was greater while consumingthe xylan and pectin diets than while consuming the other diets. These two purifiedfibers also caused higher flatus volume, hydrogen and carbon dioxide excretion. Celluloseand corn bran generally resulted in breath and flatus
4、gas excretion at levels equivalentto the fiber-free diets. Considerable variation was noted in the response of subjects toan individual diet. However, in most cases 2-5 days of frequent and daily consumptionof the diets was necessary to establish a relatively constant level of gas excretion. Thistim
5、e may represent the period of microbial and enzymatic adaptation to the new dietaryconstituents. J. Nutr. 112: 1133-1143, 1982.INDEXING KEY WORDS flatus humans gases pectin xylan cellulose corn bran fermentation fiberEpidemiological evidence has related alow-fiber diet to greater incidence of diseas
6、esincluding cancer of the colon and rectum,diabetes, obesity, appendicitis, hiatus hernia,hemorrhoids and varicose veins (1, 2). Research has provided logical explanations forthese associations, in some cases. However,the chemical heterogeneity and the diversephysiological functions of compounds not
7、digested by mammalian enzymes, andthereby categorized as dietary fibers, havecaused confusion and difficulties in the interpretation of results. Naturally occurringplant carbohydrates which are indigestibleby mammalian enzymes include pectins,hemicellulose and cellulose.Pectins are composed primaril
8、y of a-1,4-linked polygalacturonic acid units, which arerandomly interrupted with rhamnopyranoseresidues, have side chains of arabinose, galactose and xylose, and are methoxylated tovarying degrees (3, 4). Pectins are water soluble and are excreted to varying extents (5,6) presumably a function of t
9、he quantity ingested. Pectins have a hypocholesterolemiceffect on humans, and researchers speculatethat this is the result of their inhibiting reab-sorption of cholesterol and, perhaps more importantly, bile salts from the intestines (7).Additionally, pectins have been shown tohave depressing effect
10、s on postprandial serumglucose and insulin levels (8, 9).Hemicelluloses are composed of variousproportions of xylose and arabinose units andmay have side chains composed of galactose,glucose or mannose (3, 10). This diversegroup of carbohydrates is difficult to chemically characterize and shows wide
11、 variabilityin molecular weight, solubility and physiological function. Cellulose is ubiquitous in1982 American Institute of Nutrition. Received for publication 30October 1981.1Supported in part by N1H grant POI AM 10202 and USDA grant 12-14-9001-290 Reported, in part, at the XII International Congr
12、ess of Nutrition, August ld-21 1981,San Diego, CA.1133by guest on December 30, 2012jn.nutrition.orgDownloaded from 1134 MARTHINSEN AND FLEMINGplant material and is a (8-1,4glucose polymer(11). Hydrogen bonds between these polymers result in structural strength and insolubility in water (12).The effe
13、cts of dietary fibers on health appear to be largely due to their action withinthe large intestine of humans. Microbes thatreside both in the lumen and on the mucosaare able to produce enzymes that hydrolyzeundigested food residues and endogenouslyexcreted components. The products of hydrolysis can
14、then be fermented by these orother microbes. Volatile fatty acids and lacticacid are also formed (13, 14). Fermentationswithin the large intestine can also result inthe formation of gases including hydrogen,carbon dioxide and methane (15, 16). Intestinal pain or social discomfort are often associate
15、d with the formation of these gases.Anecdotal information suggests that dietary fibers are fermented to gases in somepersons, but there is little scientific evidenceof this. Tadesse and Eastwood (17) measuredbreath hydrogen and methane concentrations following single-dose feedings of dietary fibers.
16、 Only hemicellulose significantlyincreased breath hydrogen concentration,whereas cellulose and pectin did not affecthydrogen or methane concentrations. In asimilar type of study (18), the subjects showedhigher concentrations of hydrogen in theirbreath when they consumed 20 or 30 g ofwheat bran, than when only 10 g were eaten.However, no values were provided for abran-free diet. In a third study., cereal fractions were fed at breakfast meals for 3 consecutive days to eld
