Probiotics are live microorganisms that impart digestive health benefits to the host and can be found in yogurt and other fermented foods, along with dietary supplements. Prebiotics are non-digestible fibers (e.g., oligosaccharides) that are selectively fermented by the gut bacteria that produce beneficial metabolites (e.g., short-chain fatty acids) that positively influence intestinal function, metabolism, and epithelial integrity. Synbiotics contain both prebiotics and probiotics that promote beneficial microflora proliferation and maintenance and help suppress growth of non-commensal bacteria. It is well-known in scientific literature that these beneficial microbes and their metabolites have a positive effect on various aspects of gastrointestinal physiology and can contribute to overall health and wellness of the host. What about weight management? 

Probiotics and Obesity

According to the World Health Organization, obesity, now classified as an epidemic, has tripled since the 1970s and is currently touted as the 21st century’s greatest public health challenge. Being overweight and obese are risk factors for other non-communicable diseases such as diabetes, cardiovascular disease, and fatty liver disease. Research shows that the intestinal microbiota profile (i.e., gut microbiome composition) plays a role in the pathogenesis of obesity and associated diseases.

Compared to people with normal weight, the intestinal microbiota of obese or overweight individuals is characterized by decreased microbial diversity and dysbiosis. A higher Firmicutes-to-Bacteriodetes (F/B) ratio is observed in obesity compared to normal weight. A lower proportion of Bacteriodetes and higher Firmicutes is shown to facilitate energy extraction from food and increase energy storage in the host’s fat tissue. It can also suppress the production of fasting-induced adipose factor resulting in increased triglyceride accumulation in adipose tissue and decrease glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) hormone release. These gut-derived hormones suppress appetite by delaying gastric emptying and promoting satiety. 

Improving this ratio and other potential microbial imbalances may aid in weight management, as demonstrated by a meta-analysis on adult subjects. This analysis found a statistically significant reduction in body weight after taking prebiotics, probiotics, and synbiotics. Another review demonstrated that orally administered probiotics, mostly from the genus Lactobacillus and Bacillus and yeast from the genus Saccharomyces, helped restore and modify an imbalanced F/B phyla ratio, which reduced weight gain. L. rhamnosus, L. sakei, L. paracasei, L. salivarius, B. amyloliquefaciens, and S. boulardii were shown to decrease the F/B ratio and reduce weight gain.

A recent systematic review of randomized controlled trials evaluated the effects of probiotic and synbiotic intake in reducing body weight or body fat in overweight or obese populations who are otherwise healthy. The probiotic doses ranged between 106 and 5 x 1010 CFU and the duration of the studies ranged from 4 weeks to 36 weeks. Specific strains from the Lactobacillus and Bifidobacterium genus, whether used as a single-strain or multi-strain, were shown to have the potential to aid in fat mass and weight loss in overweight and obese populations. An intervention duration of at least 12 weeks showed positive effects on anthrometric measurements. 

Another systematic review and meta-analysis of 26 randomized controlled trials examined the effects of probiotics on body adiposity and cardiovascular risk markers in overweight and obese populations. The results showed both single and multi-strain probiotics significantly reduced body weight, body mass index (BMI), waist circumference, tumor necrosis factor-alpha, insulin, total cholesterol, and low-density lipoprotein (LDL) cholesterol levels compared with the controls. Significant decreases in body adiposity parameters were only observed in the studies using dosages of ≥1010 CFU for ≥8 weeks duration.

Along with dietary and lifestyle modifications, probiotics and synbiotics may help support healthy weight management in overweight and obese populations. It’s important for patients to discuss this with their health-care practitioner before supplementing. Although it’s clear that balance and gut microbiome health is critical for maintaining energy metabolism homeostasis, more long-term clinical trials are needed to fully elucidate the effects of probiotic and synbiotic intake for weight management in obesity. 

By Caitlin Higgins, MS, CNS