Microbiota and SCFA in Lean and Overweight Healthy Subjects

Abstract

articles epidemiology led to the hypothesis that Methanobrevibacter smithii may be a therapeutic target for the reduction of energy harvest in obese humans (25,26), as M. smithii is the major representative of the human gut methanogens (27).The purpose of this study was to investigate whether the proposed role of SCFA and microbiota composition in obesity, which was based on proof of principle experiments, can be confirmed in a larger study which did not exclude all confounding factors. Methods and Procedures Volunteer recruitmentLean and obese volunteers of both sexes were recruited from the Institute of Microecology and from the obesity consultation hours at the University of Giessen and Marburg. In total 98 volunteers (34 males and 64 females) took part in the study. All of the samples collected were analysed. The volunteers were aged 47 ± 13 year (mean ± s.e.m.: range 14-74 year). The BMI in kg/m 2 of 30 volunteers was within the normal range (18.5-24.9), while 35 were overweight (25.0-29.9) and 33 were obese (≥30.0). Of the latter, 17 were classified as obesity class 1 (30-35), 11 as class 2 (35-40), and 5 as class 3 (>40). No antibiotics had been taken in the 6 months prior to the study. All participants subsisted primarily on a western diet and all volunteers provided informed, signed consent.

Association of Obesity with Serum Leptin, Adiponectin, and Serotonin and Gut Microflora in Beagle Dogs

“…Our results are consistent with human studies 35. Schwiertz et al36 analyzed fecal microbiota by real‐time polymerase chain reaction (RT‐PCR) instead of pyrosequencing and observed that the proportion of Bacteroidetes was increased in the fecal microbiota of obese humans. Other studies observed no differences in the proportions of Bacteroidetes and Firmicutes in lean and obese individuals 37, 38.…”

Pediatric obesity is associated with an altered gut microbiota and discordant shifts in Firmicutes populations

“…The significantly higher concentration of SCFAs in obese participants in our study may indicate that in obese children colonic fermentation is elevated, or alternatively that there is decreased SCFA absorption due to low‐grade inflammation or more rapid gut transit. This has previously been observed in cohorts of both children (Payne et al ., 2011) and adults (Schwiertz et al ., 2009; Fernandes et al ., 2014). Elevated fecal concentrations of total or individual SCFAs might result from increased microbial production, shifts in microbial cross‐feeding patterns or low mucosal absorption (Schwiertz et al ., 2009).…”

“…This has previously been observed in cohorts of both children (Payne et al ., 2011) and adults (Schwiertz et al ., 2009; Fernandes et al ., 2014). Elevated fecal concentrations of total or individual SCFAs might result from increased microbial production, shifts in microbial cross‐feeding patterns or low mucosal absorption (Schwiertz et al ., 2009). …”

“…One of the main activities of the gut microbiota is to break down substrates such as resistant starch and dietary fiber, which are incompletely hydrolysed by host enzymes in the small intestine. The main fermentation products resulting from fiber breakdown are the short chain fatty acids (SCFAs) acetate, propionate and butyrate, which play different roles in energy salvage (Schwiertz et al ., 2009). Microbially‐derived SCFAs provide an additional source of energy for the body: propionate is taken up by the liver and used as a precursor for liponeogenesis, gluconeogenesis and protein synthesis; acetate is used as a substrate for cholesterol synthesis; and butyrate is the main energy supply for colonic epithelial cells (Kallus et al ., 2012).…”

“…The adult human gastrointestinal tract microbiota has been extensively studied in relation to its role in gut homeostasis and various diseases (Schwiertz et al ., 2009). Notably, alterations in the gut microbiome and metabolome have been associated with the development of obesity (Choquet et al ., 2010; Vinolo et al ., 2011).…”