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Microbes & Immunity Management of obesity

Table 2. Comparison of gut microbiota in obese and non‑obese individuals
Group ↑ Gut microbes ↓ Gut microbes Firmicutes: Bacteroidetes References
Non-obese Actinobacteria (phylum), Bacteroidetes (phylum), Firmicutes (phylum), Lactobacillales 0.9 127
individuals Bifidobacterium, Bacteroides, Prevotella (order), Clostridium
Obese Firmicutes (phylum), Lactobacillales (order), Actinobacteria (phylum), Bacteroidetes 1.7 127
individuals Clostridium (phylum), Bifidobacterium, Bacteroides,
Prevotella

13. Obesity and cardiovascular disorders Probiotics are currently widely applied in the prevention
and treatment of various diseases, including periodontal
The gut microbiota, when subjected to unhealthy dietary conditions and gastrointestinal infections, with particular
patterns, metabolizes dietary nutrients into metabolically emphasis on Lactobacillus and Bifidobacterium species.
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harmful substances. Examples include imidazole As commensal microorganisms in the human gut,
propionate, branched-chain amino acids (BCAAs), and probiotics are believed to exert beneficial effects through
trimethylamine N-oxide (TMAO). The microorganisms mechanisms, such as competing with pathogenic bacteria,
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Bacteroides vulgatus and Prevotella copri promote the enhancing gut barrier function, and regulating immune
synthesis of BCAAs, whereas Eggerthella lenta and responses. Recent studies involving both animals and
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Streptococcus mutans are known to produce imidazole humans have demonstrated that probiotics can effectively
propionate. Elevated circulating levels of BCAAs improve metabolic disorders, reduce inflammation,
are significant risk factors for insulin resistance, and and mitigate weight gain in individuals with obesity.
BCAA-related microbial metabolites, such as imidazole The probiotic VSL#3, which includes Bifidobacteria and
propionate, adversely affect insulin signaling cascades. Lactobacillus strains, has been utilized in mouse models
TMAO has garnered significant interest because of its to address obesity by enhancing insulin sensitivity,
potential role in cardiovascular disease. Trimethylamine decreasing food intake, and inhibiting weight gain. In
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is produced by the gut microbiota from compounds, such a randomized controlled trial, VSL#3 usage in human
as choline, phosphatidylcholine, betaine, and L-carnitine, subjects demonstrated improvements in insulin sensitivity
which are abundant in seafood, egg yolks, dairy products, and lipid profiles. The probiotic powder Lactobacillus
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and red meat. Trimethylamine is absorbed into the portal plantarum Dad-13 demonstrated the ability to alter gut
circulation and oxidized to TMAO in the liver by flavin- microbiota composition in a double-blind, placebo-
containing monooxygenase 3. TMAO and its dietary controlled trial, resulting in a decrease in Firmicutes and an
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pre-cursors promote arteriosclerosis through pathways increase in Bacteroidetes, alongside significant reductions
involving inflammation, platelet aggregation, oxidative in body weight and body mass index. Another double-
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stress, and thrombosis. Consequently, gut dysbiosis results blind, randomized trial found that the supplementation
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in elevated plasma TMAO levels, which are associated with with a probiotic mix (Bifidobacterium, Lactococcus,
cardiovascular disease and increased overall mortality. 103 and Lactobacillus) in overweight and obese individuals
LPSs are glycolipid molecules that constitute crucial increased antioxidant enzyme activity and reduced
components of the outer membrane components of abdominal adiposity. Nonetheless, a recent meta-analysis
Gram-negative bacteria and act as bacterial endotoxins, of randomized controlled human studies indicated that the
contributing to cardiometabolic abnormalities. Elevated association between weight loss and probiotics treatment
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LPS levels can induce the expression of pro-inflammatory was not statistically significant. Furthermore, the specific
cytokines, leading to endothelial damage, enhanced bacterial species, optimal dosages, and treatment durations
oxidation of low-density cholesterol particles, and foam necessary to effectively enhance obesity management
cell formation, processes that collectively accelerate require additional research.
atherosclerosis. 105
14.2. Prebiotics
14. Prevention of obesity by modulation of Prebiotics are indigestible components specifically used
gut microbiota by host microbiota, offering beneficial effects primarily by
alleviating gut dysbiosis. Several studies have indicated
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14.1. Probiotics
that prebiotics may improve dysbiosis, metabolic disorders,
The World Health Organization defines probiotics as “living and chronic inflammation associated with obesity.
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microorganisms that provide the host with beneficial Common prebiotics include inulin, various forms of
effects when administered in sufficient quantities.” lactulose, oligosaccharides, and resistant starch. It is
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Volume 2 Issue 4 (2025) 52 doi: 10.36922/MI025160036