Quantification of in vivo colonic short chain fatty acid production from inulin

Short chain fatty acids ( SCFA), including acetate, propionate, and butyrate, are produced during bacterial fermentation of undigested carbohydrates in the human colon. In this study, we applied a stable-isotope dilution method to quantify the in vivo colonic production of SCFA in healthy humans after consumption of inulin. Twelve healthy subjects performed a test day during which a primed continuous intravenous infusion with [ 1- C-13] acetate, [ 1- C-13] propionate and [ 1- C-13] butyrate ( 12, 1.2 and 0.6 mu mol center dot kg - 1 center dot min - 1, respectively) was applied. They consumed 15 g of inulin with a standard breakfast. Breath and blood samples were collected at regular times during the day over a 12 h period. The endogenous rate of appearance of acetate, propionate, and butyrate was 13.3 +/- 4.8, 0.27 +/- 0.09, and 0.28 +/- 0.12 mu mol center dot kg - 1 center dot min (-1), respectively. Colonic inulin fermentation was estimated to be 137 +/- 75 mmol acetate, 11 +/- 9 mmol propionate, and 20 +/- 17 mmol butyrate over 12 h, assuming that 40%, 10%, and 5% of colonic derived acetate, propionate, and butyrate enter the systemic circulation. In conclusion, inulin is mainly fermented into acetate and, to lesser extents, into butyrate and propionate. Stable isotope technology allows quantifying the production of the three main SCFA in vivo and proved to be a practical tool to investigate the extent and pattern of SCFA production

Systemic availability and metabolism of colonic-derived short-chain fatty acids in healthy subjects: a stable isotope study

The short-chain fatty acids (SCFAs), acetate, propionate and butyrate, are bacterial metabolites that mediate the interaction between the diet, the microbiota and the host. In the present study, the systemic availability of SCFAs and their incorporation into biologically relevant molecules was quantified. Known amounts of 13C-labelled acetate, propionate and butyrate were introduced in the colon of 12 healthy subjects using colon delivery capsules and plasma levels of 13C-SCFAs 13C-glucose, 13C-cholesterol and 13C-fatty acids were measured. The butyrate-producing capacity of the intestinal microbiota was also quantified. Systemic availability of colonic-administered acetate, propionate and butyrate was 36%, 9% and 2%, respectively. Conversion of acetate into butyrate (24%) was the most prevalent interconversion by the colonic microbiota and was not related to the butyrate-producing capacity in the faecal samples. Less than 1% of administered acetate was incorporated into cholesterol and <15% in fatty acids. On average, 6% of colonic propionate was incorporated into glucose. The SCFAs were mainly excreted via the lungs after oxidation to 13CO2, whereas less than 0.05% of the SCFAs were excreted into urine. These results will allow future evaluation and quantification of SCFA production from 13C-labelled fibres in the human colon by measurement of 13C-labelled SCFA concentrations in blood

Korte keten vetzuren in het humane colon en hun impact op de gezondheid

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Quantification of Plasma or Serum Short-chain Fatty Acids: Choosing the Correct Blood Tube

Short-Chain Fatty Acids (SCFA; acetate, propionate and butyrate) are more and more recognised as mediators of local gut and systemic health. Quantification of SCFA in plasma and serum is challenging due to their low concentrations in human blood and the ubiquitous nature of acetate, requiring careful standardisation of the sample preparation procedure. Also the choice of the blood tube might affect the resulting concentrations. SCFA concentrations were measured in blood samples (10 mL), collected from 10 healthy subjects in 7 different blood tubes. Control samples included milliQ (MQ) water and standard SCFA solutions. After pre concentration and clean-up of the samples using a hollow fibre liquid membrane extraction, SCFA concentrations were measured using gas chromatography (GC) coupled to Flame Ionisation Detection (FID). Acetate concentrations were significantly higher (ANOVA, p<0.01) when blood was collected in an EDTA K2 tube, where as propionate and/or butyrate levels were significantly higher in plasma prepared in a PST tube and a Barricor tube and serum prepared in a SST tube (ANOVA, p<0.01 for all three tubes). Similar profiles of contamination were observed when analysing standard SCFA solutions that had been centrifuged in the different blood tubes. Lowest levels of contamination were observed when using red top glass serum tubes. A red top glass serum tube is the preferred tube to collect blood for the quantification of SCFA. When plasma is preferred over serum, a lithium heparin tube is the most appropriate test tube.status: publishe

Quantification of in Vivo Colonic Short Chain Fatty Acid Production from Inulin

Short chain fatty acids (SCFA), including acetate, propionate, and butyrate, are produced during bacterial fermentation of undigested carbohydrates in the human colon. In this study, we applied a stable-isotope dilution method to quantify the in vivo colonic production of SCFA in healthy humans after consumption of inulin. Twelve healthy subjects performed a test day during which a primed continuous intravenous infusion with [1-(13)C]acetate, [1-(13)C]propionate and [1-(13)C]butyrate (12, 1.2 and 0.6 μmol·kg(-1)·min(-1), respectively) was applied. They consumed 15 g of inulin with a standard breakfast. Breath and blood samples were collected at regular times during the day over a 12 h period. The endogenous rate of appearance of acetate, propionate, and butyrate was 13.3 ± 4.8, 0.27 ± 0.09, and 0.28 ± 0.12 μmol·kg(-1)·min(-1), respectively. Colonic inulin fermentation was estimated to be 137 ± 75 mmol acetate, 11 ± 9 mmol propionate, and 20 ± 17 mmol butyrate over 12 h, assuming that 40%, 10%, and 5% of colonic derived acetate, propionate, and butyrate enter the systemic circulation. In conclusion, inulin is mainly fermented into acetate and, to lesser extents, into butyrate and propionate. Stable isotope technology allows quantifying the production of the three main SCFA in vivo and proved to be a practical tool to investigate the extent and pattern of SCFA production.status: publishe

Systemic availability and metabolism of colonic-derived short-chain fatty acids in healthy subjects: a stable isotope study

The short-chain fatty acids (SCFAs) are bacterial metabolites produced during the colonic fermentation of undigested carbohydrates, such as dietary fibre and prebiotics, and can mediate the interaction between the diet, the microbiota and the host. We quantified the fraction of colonic administered SCFAs that could be recovered in the systemic circulation, the fraction that was excreted via the breath and urine, and the fraction that was used as a precursor for glucose, cholesterol and fatty acids. This information is essential for understanding the molecular mechanisms by which SCFAs beneficially affect physiological functions such as glucose and lipid metabolism and immune function.status: publishe