Fermentation potential of the gut microbiome: implications for energy homeostasis and weight management

Abstract

Energy homeostasis is regulated by twin factors, energy intake and energy expenditure. Obesity arises when these two factors are out of balance. Recently, the microflora residing in the human gut has been found to be one of the influential factors disturbing energy balance. Recent interest in this field has led to use of the term "gut microbiome" to describe the genomes of trillions of microbes residing in the gut. Metagenomic studies have shown that the human gut microbiome facilitates fermentation of indigestible carbohydrates to short-chain fatty acids that provide excess energy to the body, thus contributing to the obese phenotype. Alteration in the ratio of Bacteroidetes and Firmicutes drives a change in fermentation patterns that could explain weight gain. Therefore, changes in the gut microbiome (induced by antibiotics or dietary supplements) may be helpful in curbing the obesity pandemic. This review provides information on the expansive role the gut microbiome is believed to play in obesity and other related metabolic disorders.

Levansucrases of a Pseudomonas syringae pathovar as catalysts for the synthesis of potentially prebiotic oligo- and polysaccharides

“…The colon microbiota co-develops with the host, changes from birth to old age and is affected by the genome, but also lifestyle and nutritional habits of the host as well as antibiotic treatment and other factors [3][4][5]. Among those, food plays a key role [1,[5][6][7]. For a fresh review on significance of food, gut microbiota and its metabolites as epigenetic effectors in humans and animals, see [8].…”

“…Complex carbohydrates (also referred to as food fiber) are specifically suited to manipulate the human colon microbiota as they resist human digestion system, reach to the colon and serve as food for resident bacteria. Millennia of human-bacteria co-evolution have equipped the gut microbiota with potent tools for the degradation of complex carbohydrates: resistant starch, inulin, xylan, pectin [1,11,12] and some others. The colon bacteria also feed on oligosaccharides of breast milk and those attached to gut mucins [11,13].…”

“…The colon bacteria, comprising a major part of it, are involved in many functions: food digestion, food energy harvest and storage, vitamin production, mineral absorption, development and stimulation of the immune system, and maintenance of the intestinal barrier integrity [1][2][3][4]. The colon microbiota co-develops with the host, changes from birth to old age and is affected by the genome, but also lifestyle and nutritional habits of the host as well as antibiotic treatment and other factors [3][4][5].…”

Kefir drink leads to a similar weight loss, compared with milk, in a dairy-rich non-energy-restricted diet in overweight or obese premenopausal women: a randomized controlled trial

“…Another strategy, which again has just become popular in recent years, is the use of non-energy-restricted diets rich in probiotics, usually provided in the form of fermented dairy products, as there is growing evidence regarding the significant contribution of gut microbiota to energy homeostasis and weight control [27]. However, despite the escalating literature supporting the potential of probiotics as antiobesity agents in experimental animals [28], the few RCTs in humans assessing the effects of non-energyrestricted diets rich in probiotic dairy products on anthropometric indices such as weight, body mass index (BMI), waist circumference (WC), and fat mass have been relatively less conclusive [29][30][31][32].…”

Identification of Oligosaccharides in Feces of Breast-fed Infants and Their Correlation with the Gut Microbial Community

“…HMOs are not catabolized directly by the infant, but instead pass undigested through the upper digestive tract to the large intestine where they function as prebiotics for the distal gut microbiota (4, 14 -16). HMOs help promote a healthy infant gastrointestinal tract in a number of ways: as anti-adhesives preventing viruses from binding to epithelial cell surface glycans, as antimicrobials acting as decoy receptors to pathogenic bacteria, and as energy sources for beneficial bacteria which in turn produce short-chain fatty acids for the infant (4,6,17,18). Commensal bacteria such as Bifidobacterium and Bacteroides are equipped with a suite of enzymes capable of breaking down HMOs (19 -21).…”