Reduced Dietary Intake of Carbohydrates by Obese Subjects Results in Decreased Concentrations of Butyrate and Butyrate-Producing Bacteria in Feces

• Published in: Applied and Environmental Microbiology Vol. 73; no. 4; pp. 1073 - 1078
• Main Authors: Duncan, Sylvia H, Belenguer, Alvaro, Holtrop, Grietje, Johnstone, Alexandra M, Flint, Harry J, Lobley, Gerald E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.02.2007
• Subjects: Adult; bacteria; Bacteria - metabolism; Bacteriology; Bacteroides; Biological and medical sciences; body mass index; butyrates; Butyrates - metabolism; carbohydrate intake; Carbohydrates; Diet; Diet, Carbohydrate-Restricted; Diet, Reducing; dietary carbohydrate; Eubacterium rectale; fatty acids; feces; Feces - microbiology; fluorescence in situ hybridization; Fundamental and applied biological sciences. Psychology; high performance liquid chromatography; Humans; Large intestine; Liquid chromatography; Male; Microbial activity; Microbial Ecology; Microbiology; Middle Aged; Obesity; Obesity - diet therapy; protein intake; Proteins; Roseburia; Weight control; weight loss; Bacteria; Carbohydrate; Concentration; Feces; Diet; Butyrate
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.02340-06

Weight loss diets for humans that are based on a high intake of protein but low intake of fermentable carbohydrate may alter microbial activity and bacterial populations in the large intestine and thus impact on gut health. In this study, 19 healthy, obese (body mass index range, 30 to 42) volunteers were given in succession three different diets: maintenance (M) for 3 days (399 g carbohydrate/day) and then high protein/medium (164 g/day) carbohydrate (HPMC) and high protein/low (24 g/day) carbohydrate (HPLC) each for 4 weeks. Stool samples were collected at the end of each dietary regimen. Total fecal short-chain fatty acids were 114 mM, 74 mM, and 56 mM (P < 0.001) for M, HPMC, and HPLC diets, respectively, and there was a disproportionate reduction in fecal butyrate (18 mM, 9 mM, and 4 mM, respectively; P < 0.001) with decreasing carbohydrate. Major groups of fecal bacteria were monitored using nine 16S rRNA-targeted fluorescence in situ hybridization probes, relative to counts obtained with the broad probe Eub338. No significant change was seen in the relative counts of the bacteroides (Bac303) (mean, 29.6%) or the clostridial cluster XIVa (Erec482, 23.3%), cluster IX (Prop853, 9.3%), or cluster IV (Fprau645, 11.6%; Rbro730 plus Rfla729, 9.3%) groups. In contrast, the Roseburia spp. and Eubacterium rectale subgroup of cluster XIVa (11%, 8%, and 3% for M, HPMC, and HPLC, respectively; P < 0.001) and bifidobacteria (4%, 2.1%, and 1.9%, respectively; P = 0.026) decreased as carbohydrate intake decreased. The abundance of butyrate-producing bacteria related to Roseburia spp. and E. rectale correlated well with the decline in fecal butyrate.