Towards microbial fermentation metabolites as markers for health benefits of prebiotics

Abstract

Available evidence on the bioactive, nutritional and putative detrimental properties of gut microbial metabolites has been evaluated to support a more integrated view of how prebiotics might affect host health throughout life. The present literature inventory targeted evidence for the physiological and nutritional effects of metabolites, for example, SCFA, the potential toxicity of other metabolites and attempted to determine normal concentration ranges. Furthermore, the biological relevance of more holistic approaches like faecal water toxicity assays and metabolomics and the limitations of faecal measurements were addressed. Existing literature indicates that protein fermentation metabolites (phenol, p-cresol, indole, ammonia), typically considered as potentially harmful, occur at concentration ranges in the colon such that no toxic effects are expected either locally or following systemic absorption. The endproducts of saccharolytic fermentation, SCFA, may have effects on colonic health, host physiology, immunity, lipid and protein metabolism and appetite control. However, measuring SCFA concentrations in faeces is insufficient to assess the dynamic processes of their nutrikinetics. Existing literature on the usefulness of faecal water toxicity measures as indicators of cancer risk seems limited. In conclusion, at present there is insufficient evidence to use changes in faecal bacterial metabolite concentrations as markers of prebiotic effectiveness. Integration of results from metabolomics and metagenomics holds promise for understanding the health implications of prebiotic microbiome modulation but adequate tools for data integration and interpretation are currently lacking. Similarly, studies measuring metabolite fluxes in different body compartments to provide a more accurate picture of their nutrikinetics are needed.

Growth Inhibition of an Opportunistic Yeast Pathogen <i>Trichosporon asahii</i> by <i>Staphylococcus epidermidis</i>

“…[19][20][21][22][23] We purified and analyzed the molecule produced by S. epidermidis that inhibited an opportunistic fungal pathogen, T. asahii, and identified it as lactic acid. We attempted quantitative analysis of lactic acid in the culture supernatant of S. epidermidis by HPLC.…”

Effect of lactulose intervention on gut microbiota and short chain fatty acid composition of C57BL/6J mice

“…Straightchain SCFAs are mainly produced by microbial fermentation of unabsorbed dietary carbohydrates in the gut. Lactate and succinate can also be metabolized to straight-chain SCFAs, including acetate, propionate, and butyrate (Hasebe et al, 2016;Verbeke et al, 2015). Straight-chain SCFAs have a range of beneficial effects, including regulation of the colonic and intracellular environment (Wong et al 2006), and modulation of cell proliferation and gene expression.…”

“…Straightchain SCFAs are mainly produced by microbial fermentation of unabsorbed dietary carbohydrates in the gut. Lactate and succinate can also be metabolized to straight-chain SCFAs, including acetate, propionate, and butyrate (Hasebe et al, 2016;Verbeke et al, 2015). Straight-chain…”

Continuous combined intake of polydextrose and lactitol stimulates cecal fermentation and salivary IgA secretion in rats

“…Short-chain fatty acids (SCFAs), such as acetic, propionic, and butyric acids, are the major metabolites of anaerobic microbial fermentation of polysaccharides in the forestomach and hindgut (12). SCFAs are implicated in lipid and protein metabolism, colonic health, and immunity, suggesting that gut microflora may modulate host immune status through fermentation of dietary fiber to SCFAs (13). Polydextrose (PDX) and lactitol are fermentable peptic carbohydrates known to increase SCFA production (14,15,16).…”