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Colonic Fermentation of Ispaghula, Wheat Bran, Glucose, and Albumin to Short‐Chain Fatty Acids and Ammonia Evaluated in Vitro in 50 Subjects
Author(s) -
Mortensen Per Brøbech,
Clausen Mette Rye,
Bonnén Helen,
Hove Hanne,
Holtug Klavs
Publication year - 1992
Publication title -
journal of parenteral and enteral nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.935
H-Index - 98
eISSN - 1941-2444
pISSN - 0148-6071
DOI - 10.1177/0148607192016005433
Subject(s) - short chain fatty acid , bran , food science , albumin , fermentation , chemistry , in vitro , biochemistry , urea , fatty acid , butyrate , raw material , organic chemistry
The production of short‐chain fatty acids and ammonia was measured in 16.6% fecal homogenates from 50 subjects incubated at 37°C for 6 and 24 hours. All 50 homogenates produced ammonia and short‐chain fatty acids of any chain length (C2‐C5). Incubation for 24 hours with dietary fiber (ispaghula husk or wheat bran), albumin, or glucose (10 mg/ mL) increased the short‐chain fatty acid production (43.6 ± 2.8, 45.4 ± 2.0, 60.3 ± 3.2, and 65.8 ± 3.1 mmol/L, respectively) compared with controls (21.4 ± 1.3 mmol/L). The degradation of different substrates was associated with the production of different amounts of ammonia and short‐chain fatty acids. Ispaghula, wheat bran, albumin, and glucose were fermented to acetate (>2 mmol/L; 24‐hour incubations) in 86%, 96%, 98%, and 98% of the homogenates, to propionate in 80%, 76%, 100%, and 68%, and to butyrate in 32%, 94%, 88%, and 54% of the homogenates, respectively. Isobutyrate, valerate, and isovalerate were produced from albumin in all (100%) of the homogenates, but only in 2 to 4% of the homogenates incubated with ispaghula or glucose. Ammonia was always (100%) produced after the addition of albumin and always (98%) consumed (assimilated) when glucose was fermented. Surgery (sigmoid or right‐ or left‐sided colonic resection) did not change the pattern of ammonia and short‐chain fatty acid production from these substrates. This study suggests that the different colonic flora from a large number of subjects share general biochemical characteristics, which metabolize different substrates to specific patterns of ammonia and short‐chain fatty acids. (Journal of Parenteral and Enteral Nutrition 16: 433–439, 1992)