Probiotics are simply bacteria that are beneficial to our bodies, particularly our digestive systems. They are present in foods like yogurt, kimchi, buttermilk, tofu, idly, dosa, dhokla and sauerkraut. Our guts contain a mix of good and bad bacteria, and a healthy supply of probiotics can make the good grow while keeping the bad at bay.
The microbiota (the full collection of microbes that naturally exist within a particular biological niche) has a profound influence on human physiology, affecting metabolism and the immune system and protecting against pathogens while modulating gastrointestinal (GI) development. Perturbations in the composition of the microbiota may be especially important during early life, when the immune system is still developing. Gut microbiota play several crucial roles in host physiology such as immune modulation, digestion of indigestible food materials, and production of vitamins, bile acids, bioactive compounds [conjugated linoleic acid (CLA), bacteriocins]. They are also known to be involved in the degradation of toxins, carcinogens, inhibition of enteric pathogens, and maintenance of intestinal epithelia, all of which the host cannot achieve alone.
Gut microbiota have a suppressive effect on AMPK activity, which in turn affect fatty acid oxidation and make the host susceptible to obesity. Activation of AMPK by probiotics lead to increase in fatty acid oxidation in liver and muscle tissues, incites energy loss, and disfavour obesity.
The gut microbiota inhibits bile acid synthesis in the liver by alleviating the levels of FXR in the ileum (Sayin et al., 2013). Another mechanism by which bile acids regulate energy metabolism is by activating the G-protein-coupled bile acid receptor 1 (GPBAR1) or TGR5. This protein gets activated by interacting with secondary bile acids, as ligands, present in the intestinal lumen, thereby aiding in glucose homeostasis by activating secretion of glucagon-like peptide.
Probiotic helps in suppressing insulin-mediated fat accumulation, which in turn regulates the energy balance by inhibiting the deposition of excess energy and inducing fat consumption (Kimura et al., 2013). Another mechanism, by which gut microbiota modulate energy homeostasis via SCFAs is their effect on leptin secretion from adipocytes through GPR41/43 dependent process. So it will increases satiety value and reduced intake of excess calories.