Colonic fermentation – More than meets the nose

Abstract

Fermentation of undigested foods in the colon by its resident bacteria affects not only colonic health (protection against inflammation and tumour formation) but also influences metabolic health. Studying fermentation directly is difficult for lack of access. We hypothesise that the anatomical structure of the colon is suited to act as a fermenting chamber with the gaseous molecules (VOCs) emitted having direct effects on the colonocytes as well as gut neural and metabolic effects. We refer to this complex system as the "fermentome", and further hypothesise that alteration in the "fermentome" through dietary modification will have a direct impact on colonic as well as metabolic health and disease. The VOCs emitted may play a role in bacterial chemical signalling within the colon but importantly could also function as a "gas" biomarker. Measurement of such VOCs through non-invasive methods would have important application as a hypothesis-generating tool with subsequent clinical application.3

Application of a Novel Tool for Diagnosing Bile Acid Diarrhoea

“…VOCs and other vapours are produced as a result of colonic fermentation following a complex interaction between the colonocyte, human faecal flora, and mucosal integrity and invading pathogens [5]. They are emitted from bodily fluids and as a result, vapours emitted from urine, faeces and breath may include biomarkers of use in the assessment of gastrointestinal disease.…”

“…Modern genomic techniques can circumvent this problem but are expensive, laborious and not practical for daily clinical use. The study of the resultant products of fermentation—‘the fermentome’ can be measured for various diseases using urine and faeces [5–9]. By examining the signature of some volatiles, we have been able to distinguish those with diarrhoea due to inflammatory bowel disease (a chronic relapsing condition) [10].…”

Immunomodulatory dietary polysaccharides: a systematic review of the literature

“…Current studies investigating the link between the bioconversion of dietary polysaccharides, their bioavailability and their downstream effects on the host metabolism and physiology are utilizing metabolomic and metagenomic approaches that can detect and track diverse microbial metabolites from immunomodulatory polysaccharides [103]. These and other innovative approaches in the field of colonic fermentation are providing novel insights into gut microbial-human mutualism [110,111], its impact on regulating human health and disease, and the importance of dietary modulation [112-115]. …”

Non-Invasive Distinction of Non-Alcoholic Fatty Liver Disease using Urinary Volatile Organic Compound Analysis: Early Results

“…This would indicate that they represent the complex interaction of colonocytes, human gut microflora and invading pathogens [26]. The resultant products of fermentation, 'the fermentome' can exist in the gaseous phase and are present in exhaled air, sweat, urine and faeces [23,25,[27][28][29]. Their presence in bodily secretions from sites other than the gastrointestinal tract (sweat, exhaled air and urine) is presumed possible due to the altered gut permeability afforded in certain disease states [27].…”

“…The resultant products of fermentation, 'the fermentome' can exist in the gaseous phase and are present in exhaled air, sweat, urine and faeces [23,25,[27][28][29]. Their presence in bodily secretions from sites other than the gastrointestinal tract (sweat, exhaled air and urine) is presumed possible due to the altered gut permeability afforded in certain disease states [27]. We believe that VOCs represent a bio-signature specific to a patient that is affected by a variety of factors such as genetics, disease state and environmental factors such as diet.…”