An Overview on Fecal Branched Short-Chain Fatty Acids Along Human Life and as Related With Body Mass Index: Associated Dietary and Anthropometric Factors

Abstract

Short-chain fatty acids (SCFA) are the main bacterial products of the catabolism of carbohydrates and proteins in the gut, and their role is essential in host-microbiota interactions. Acetic, propionic, and butyric acids are the major SCFA produced in the gut, and they have been extensively studied. In contrast, branched short-chain fatty acids (BCFA), mainly isovaleric and isobutyric acids, are produced in less amounts and their fecal levels in different human groups, intestinal microbial producing populations, and influence on health are insufficiently known. They have been proposed as markers of protein fermentation, which leads to the concomitant production of other fermentation products that can be harmful for the colon epithelium. In this context, the aim of this study was to shed light into the production of BCFA by the human intestinal microbiota, as related to age, body mass index (BMI), and diet. Fecal levels of the different SCFA were analyzed by gas chromatography in 232 healthy individuals with ages between 3 months and 95 years, and BMI in adults ranging from 19 to 54. Dietary assessments in adults were obtained through a food frequency questionnaire (FFQ). Molar proportions of BCFA in feces were strongly and positively related with aging. However, not a significant relationship was obtained between BCFA and BMI. A negative correlation was found between the consumption of dietary insoluble fiber and fecal levels of BCFA. More studies are needed for improving our understanding on the relationship of BCFA production profile with the intestinal microbiota composition and human health.

Akkermansia muciniphila and environmental enrichment reverse cognitive impairment associated with high-fat high-cholesterol consumption in rats

“…In this regard, some microorganisms, such as Bacteroides or Clostridia members, are able to produce BCFAs from the proteolytic metabolism of branched-chain amino acids. The higher levels of Bacteroidaceae or Peptostreptococcaceae observed in the HFHC group could be related to the higher levels of BCFAs observed, as found in other diseases related to the gut–brain axis, such as obesity, 66 Rett syndrome, 67 or anorexia nervosa. 68 Furthermore, evidence exists in mice that acetate can alter the levels of glutamate, glutamine, and GABA, 69 and some studies have shown that SCFAs and their metabolites can stimulate vagus nerve signaling.…”

Antioxidant Vitamins and Prebiotic FOS and XOS Differentially Shift Microbiota Composition and Function and Improve Intestinal Epithelial Barrier In Vitro

“…Under physiological conditions, protein reaching the distal colon undergoes microbial proteolysis. Proteolytic fermentation metabolites, including BCFAs, hydrogen sulfide, ammonia or p-cresol, are usually linked to negative consequences to the host e.g., gut inflammation and increased cancer risk [ 31 , 32 , 33 ]. Some studies have also described a potential impact of BCFAs on gut–brain axis communication and regulation of glucose and lipid metabolism.…”

Short-Chain Fatty Acids, Maternal Microbiota and Metabolism in Pregnancy

“…In humans, the species Bacteroides and Clostridium are mainly responsible for the fermentation process of branched chain amino acids [ 8 ]. Differences in the distribution of BSCFAs concentrations in the human large intestine were observed, with a tendency to higher concentrations in the proximal part of the colon compared to the distal part and feces [ 9 ]. Both the metabolism of BSCFAs and the types of intestinal microbial populations involved in their production, as well as their role in the human body, are not yet sufficiently understood.…”