Short-Chain Fatty Acids in the Normal Human Feces

Abstract

The short-chain fatty acids ( SCFAs ) have been studied in the feces of 20 healthy subjects--10 methane excretors and 10 non-methane excretors. The analytical procedure included homogenization of fecal samples followed by vacuum distillation and subsequent gas chromatography. This method for analysis of fecal SCFAs showed recoveries of the individual acids from 90% to 109% and coefficients of variation for the inter-assay reproducibility from 6.0% to 19.7%, highest for those acids present in the smallest concentrations. There was no difference in the concentrations or relative compositions of SCFAs between methane-excreting subjects and non-methane-excreting subjects. The concentrations of SCFAs , given as mmol/kg feces (wet weight), were (median and range): total, 76.8 (27.9-187.7); acetic acid, 37.4 (12.8-103.4); propionic acid, 12.5 (4.5-27.8); i-butyric acid, 2.2 (0.7-3.8); n-butyric acid, 12.4 (4.0-53.0); i-valeric acid, 3.2 (0.8-5.9); n-valeric acid, 2.4 (0.6-3.8) and n-caproic acid, 0.5 (0.0-3.6). The study shows that the SCFAs are quantitatively the most important anions in the feces of healthy subjects. The pronounced individual variations in the concentrations of SCFAs are real biological variations and cannot be explained by methodological variations.

Fecal Fermentation in Irritable Bowel Syndrome: Influence of Dietary Restriction of Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols

“…Upon analysis, 0.5 g of the fecal material was homogenized after addition of distilled water containing 3 mmol/l of 2-ethylbutyric acid (as internal standard) and 0.5 mmol/l of H 2 SO 4 ; 2.5 ml of the homogenate was vacuum distilled, according to the method of Zijlstra et al [15], as modified by Hoverstad et al [16]. The distillate was analyzed with gas chromatography (Agilent 7890 A, Calif., USA), using a capillary column (serial No.…”

Short-Chain Fatty Acid Receptor and Its Contribution to Glucagon-Like Peptide-1 Release

“…In nonruminant mammals, SCFAs are produced by microbiota in the distal small intestine and colon from low-digestible carbohydrates, including resistant starch and soluble oligo- and poly-saccharides. The main components of SCFAs in the human colon are acetate (2-carbon), propionate (3-carbon) and butyrate (4-carbon), at a ratio of about 3:1:1 [2]. Once produced, about 90% of SCFAs are readily absorbed by colonocytes; butyrate in particular is almost entirely utilized by colonocytes [3].…”

Toxins, Butyric Acid, and Other Short-Chain Fatty Acids Are Coordinately Expressed and Down-Regulated by Cysteine in Clostridium difficile

“…For analysis of short-chain fatty acids (SCFAs), 1 ml of harvested medium was mixed with an equal volume of distilled water containing 3 mM 2-ethylbutyric acid as an internal standard and 0.5 ml of 0.5 mM H 2 SO 4 . The mixture was vacuum distilled according to the method of Zijlistra et al (27) modified by Høverstad et al (8), and the distillate was analyzed with gas-liquid chromatography on 10% SP-1200-1% H 3 PO 4 (Chromosorb) at 120°C (Perkin-Elmer Autosystem XL with Turbochrome 4 automatic analyzer system). The injector and detector temperatures were 180 and 190°C, respectively, and the carrier gas was N 2 (flow rate, 60 ml/min).…”