intestinal microbiota and obesity

Obesity is defined as excessive accumulation of fat and hypertrophy of adipose tissue. Obesity is now classified as an epidemic because it is a risk factor for many chronic diseases, such as diabetes II, cardiovascular disease, and certain types of cancer, and has generated tripled levels of obesity as compared to the year 1975, and has become one of the greatest public health challenges of the twenty-first century. Obesity is caused by multiple factors and each factor affects each other. At present, it is known that heredity, certain mental diseases, and acquired social environment are related to obesity. In recent years, animal studies have found that obesity may be caused by changes in the Intestinal Microbiota. This view can provide us with some reflections. For example, some obese people may be dysbacteriosis. Perhaps in the future, humans can also use intestinal flora changes in bacteria or take probiotics to achieve the purpose of losing weight.

70-75% of the intestinal bacteria in the human body come from two categories: Firmicutes and Bacteroides. Firmicutes bacteria prefer a high-oil and high-sugar diet. If such bacteria multiply, they will rapidly decompose fat and sugar, greatly improving the efficiency of absorbing calorie, and the endotoxin produced during the decomposition process which will cause systemic chronic inflammation. It may lead to obesity and other problems in the long run; Bacteroides bacteria can break down plant starch and fiber into short-chain fatty acids. Recent studies have demonstrated that there is a specific gut Intestinal Microbiota in obese people, characterized by dysbiosis and lower microbial diversity. From this point of view, the proportion of Bacteroidetes is lower and the proportion of Firmicutes is higher compared to people who are not obese.

In recent years, the effect of probiotics and synbiotics has gained a great deal of interest in the treatment of obesity. The results of this study suggest that probiotics and synbiotics, whether used as a single or multi-strain, can be beneficial for weight loss in obese individuals and for other relevant anthropometric markers such as waist measure, BMI, etc. Regarding the probiotic used in probiotics and synbiotics, the Lactobacillus genus stands out, including those from L. rhamnosus, L. gasseri, L. plantarum, L. casei, L. lactis, L. acidophilus. The participants with the absence of restriction of energy intake; the use of whether the strain alone or mixed with Bifidobacterium showed a weight loss effect, however these interventions had in common an intervention period ≥ 8 weeks.

Probiotics and synbiotics have been implicated in weight loss through different mechanisms. Probiotics help in the recovery of the tight junctions between epithelial cells thus reducing intestinal permeability, preventing the translocation of bacteria and reducing inflammation derived from lipopolysaccharides (LPS). The reduction in inflammation leads to increased hypothalamic insulin sensitivity, which improves satiety. In addition, due to increased satiety, increased concentrations of leptin, glucagon-like peptide 1 (GLP-1), and pancreatic polypeptide (PPY) in adipose tissue lead to decreased food intake.

Several clinical studies in recent years have shown that probiotics and synbiotics may contribute to the reduction of body weight and fat mass in obese people. There is still a need, though, for clinical trials, in order to state more accurate recommendations in terms of strains, doses and intervention times. Besides, research on gender and age is also recommended. Beyond that, ideal future trials would be conducted in the absence of other weight loss methods (such as dietary advice and physical activity programs for weight loss) to assess the specific effects of strains. In sum, if people don’t want to have a fat-prone constitution, they should eat less high-fat and high-sugar foods, eat more foods high in dietary fiber, and take more probiotics and synbiotics, which can improve the diversity and change the composition of intestinal bacteria: Decreased Firmicutes, increased Bacteroidetes, turned into a healthier intestinal flora, and maintained normal body weight.

Reference:

1. Valentina Álvarez-Arraño and Sandra Martín-Peláez. Effects of Probiotics and Synbiotics on Weight Loss in Subjects with Overweight or Obesity: A Systematic Review. Nutrients 2021, 13, 3627. https://doi.org/10.3390/nu13103627
2. Benahmed, A.G.; Gasmi, A.; Do¸sa, A.; Chirumbolo, S.; Mujawdiya, P.K.; Aaseth, J.; Dadar, M.; Bjørklund, G. Association between the gut and oral microbiome with obesity. Anaerobe 2021, 70, 102248.