Probiotics for the Treatment of Overweight and Obesity in Humans-A Review of Clinical Trials

Abstract

The World Health Organization (WHO) reports that 400 million people are obese, and over 1.6 billion adults are overweight worldwide. Annually, over 2.8 million people die from obesity-related diseases. The incidence of overweight and obesity is steadily increasing, and this phenomenon is referred to as a 21st-century pandemic. The main reason for this phenomenon is an easy access to high-energy, processed foods, and a low-activity lifestyle. These changes lead to an energy imbalance and, as a consequence, to the development of body fat. Weight gain contributes to the development of heart diseases, skeletal system disorders, metabolic disorders such as diabetes, and certain types of cancer. In recent years, there have been many works linking obesity with intestinal microbiota. Experiments on germ-free animals (GFs) have provided much evidence for the contribution of bacteria to obesity. The composition of the gut microbiota (GM) changes in obese people. These changes affect the degree of energy obtained from food, the composition and secretory functions of adipose tissue, carbohydrate, and lipid metabolism in the liver, and the activity of centers in the brain. The study aimed to present the current state of knowledge about the role of intestinal microbiota in the development of obesity and the impact of supplementation with probiotic bacteria on the health of overweight and obese patients.

Keywords: Bifidobacterium; Lactobacillus; gut microbiota; obesity; overweight; probiotic.

Figure 1

Steps for selecting the articles included in the review.

Figure 2

Risk of bias summary.

Figure 3

Risk of bias graph.

Figure 4

Inflammatory processes in the fat tissue. In obese people, the composition and number of cells in the immune system change. Reduction in the number of Treg lymphocytes, eosinophilia, and M2 macrophages and an increase in the number of B, Th1 lymphocytes, neutrophils, and M1 macrophages. Created with BioRender.com.

Figure 5

Mechanism of action of probiotics in the gastro intestinal tract: Probiotics increase the variety of intestinal microbiota. Inhibition of growth of pathogenic bacteria. Stimulating SCFA production in the gut. Regulation of appetite. Effects on glucose and lipid metabolism. Positive effect on intestinal barrier tightness. The role of intestinal microbiota in the etiology of obesity: Decreased AMPK expression causes a decrease in β-oxidation in the liver and muscles. Inhibition of ANGPTL4 increases lipoprotein lipase activity, which leads to TG storage in adipose tissue. Lowering GLP-1 levels disrupts the host’s response to insulin. Low levels of PYY cause more hunger. An increased hepatic lipogenesis by activating acetyl CoA carboxylase and fatty acid synthase. The development of inflammation in adipose tissue is caused by LPS. Stimulation of GPR 41/43 receptors increases lipolysis in adipose tissue. Activation of CB1 receptors. Abbreviations: SCFA—short chain fatty acids, GPR41/43—G-protein coupled receptor 41/43, GLP1—Glucagon Like Protein 1, PYY—peptide YY, LPS—lipopolysaccharide, TMA—trimethylamine, TMAO—Trimethylamine-N-oxide, TGR5—transmembrane G protein-coupled receptor, FXR—farnesoid X receptor, ANGPTL4—Angiopoietin Like 4, AMPK—5’AMP-activated protein kinase. Created with BioRender.com.