Role of Gut Microbiota in the Aetiology of Obesity: Proposed Mechanisms and Review of the Literature

Abstract

The aetiology of obesity has been attributed to several factors (environmental, dietary, lifestyle, host, and genetic factors); however none of these fully explain the increase in the prevalence of obesity worldwide. Gut microbiota located at the interface of host and environment in the gut are a new area of research being explored to explain the excess accumulation of energy in obese individuals and may be a potential target for therapeutic manipulation to reduce host energy storage. Several mechanisms have been suggested to explain the role of gut microbiota in the aetiology of obesity such as short chain fatty acid production, stimulation of hormones, chronic low-grade inflammation, lipoprotein and bile acid metabolism, and increased endocannabinoid receptor system tone. However, evidence from animal and human studies clearly indicates controversies in determining the cause or effect relationship between the gut microbiota and obesity. Metagenomics based studies indicate that functionality rather than the composition of gut microbiota may be important. Further mechanistic studies controlling for environmental and epigenetic factors are therefore required to help unravel obesity pathogenesis.

Determinants and Duration of Impact of Early Gut Bacterial Colonization

“…In addition, the association between the gut microbiome and obesity in adults has led to studies exploring the development of the microbiome and obesity in children. Despite evidence suggesting that a gut microbiome with lower numbers of bifidobacteria in infancy is related to later obesity [5,28] , children with hyperphagic disorders [29] , including Prader-Willi syndrome, who developed obesity had more similar gut bacterial activity to normal obese children than those with the same condition but who had not become obese indicating that the bacterial differences may have been caused by the obesity and not vice versa.…”

“…There have been several studies implicating the gut microbiota in inflammatory bowel disease [3] , irritable bowel syndrome [4] , obesity [5] , allergy [6] , autoimmune disease, and many other potential conditions including brain disorders [7] . The number and types of bacteria in the gut are important but their metabolic activity is also key to their impact in the body.…”

Effects of inclusion of dietary fibers in the composition of the diet in obesity

“…В то же время за последние годы появились клиниче-ские работы, в которых обнаружены корреляционные связи между нарушениями количественного и/или ка-чественного состава микробиоты кишечника и развити-ем различных аллергических и иммунопатологических реакций, воспалительных заболеваний кишечника, ожирения и других дисметаболических состояний [6,7]. Благодаря появлению высокоинформативных методов исследования микробиоты кишечника, таких как ана-лиз метаболитов микроорганизмов в кале -короткоце-почечных жирных кислот (КЖК), возможности изучения функциональной активности микробиоты кишечника существенно расширились [8,9,10]. В настоящее вре-мя фармацевтическая отрасль производит огромное количество лекарственных препаратов и биологи-чески активных добавок с заявленным содержанием в своем составе определенного количества различ-ных пре-и главным образом пробиотиков [7,11,12].…”

Obesity and the Microbiome - A Surgeon's Perspective

“…Some genetic factors contribute to the control and maintenance of body weight, but the dramatic increase in obesity prevalence over the past decades, suggests an additional, environmental effect. 1 The effect of the gut microbiome in controlling obesity phenotypes 2 has generated attention to its role in developing obesity. In experimental germ-free mice models, when the luminal contents from the ceca of obese or lean mice were implanted, mice receiving the microbiome of obese donors gained more weight than recipients of the lean donors, despite equivalent food intake.…”