Doctor Explains Effects Of Obesity On Gut Microbiota And Digestive Health

Obesity is a complex metabolic disorder caused by a variety of genetic and nongenetic factors (such as environmental factors). Obesity not only manifests as changes in appearance but is also associated with lipid and glucose metabolism disorders, chronic inflammation, oxidative stress and an increased risk of a variety of diseases, most notably cardiovascular disease, diabetes and cancer. In recent years, increasing evidence has shown that an imbalance in the gut microbiota may be a factor leading to obesity. Up to 100 trillion symbiotic microbes live in the gut called the gut microbiota which comprises 10 times the number of cells in the body itself.

In a conversation with Jagran English, Dr. Vikas Singla, Senior Director & Head – Gastroenterology, Hepatology & Endoscopy, Max Super Speciality Hospital, Saket explained the effect of obesity on gut microbiota and digestive health.

The active gut microbiota will produce substances including short-chain fatty acids, vitamins and health-beneficial products such as anti-inflammatory, analgesic and antioxidant products along with potentially harmful products such as neurotoxins, carcinogens and immunotoxins. These products can enter the blood directly regulate the expression of genes and affect human immune and metabolic processes. Therefore, a healthy gut microbiota is essential for maintaining the body’s metabolism and energy balance. An imbalance in the gut microbiota can cause metabolic disorders and increase central appetite, leading to obesity.

Recent research has linked obesity to specific gut bacteria including Christensenellaceae, Methanobacteriales, Lactobacillus, Bifidobacterium and Akkermansia. Christensenellaceae, in particular, is associated with weight loss with its abundance inversely related to BMI. Akkermansia muciniphila has also been shown to support weight loss and improve metabolic health in obese individuals. Traditional probiotics like Lactobacillus and Bifidobacterium help maintain intestinal balance though their effects on weight vary by species. For example, Lactobacillus paracasei is negatively correlated with obesity while Lactobacillus reuteri and L. gasseri are linked to higher obesity levels. Animal studies suggest Bifidobacterium may resist obesity.

The gut microbiome’s role in obesity is strain-specific with beneficial and harmful bacteria existing within the same taxonomic groups. Recent studies have introduced the concept of “guilds” to group microbes with similar functions. Gut microbiota diversity is generally lower in obese individuals although some studies suggest no direct link between diversity and disease. Overall, obesity appears related to dysbiosis in the bacterial ecosystem.

OBESITY MECHANISMS INDUCED BY THE GUT MICROBIOTA

Energy Absorption

Studies have found that people with predominantly microbiota associated with obesity have increased consumption of carbohydrates and protein through the gut microbiota to provide energy for the host. Therefore, the gut microbiota of obese patients can promote the absorption of energy, resulting in excessive accumulation of energy and increased weight gain.

Central appetite

In recent years, the microbiota has emerged as one of the key regulators of gut-brain function. This gut-brain axis has received increasing attention in the study of the biological and physiological bases of obesity and its related diseases. The microbiota and the brain communicate with each other through a variety of pathways, including endocrine, immune, and neural pathways. The central nervous system can also affect the composition and structure of the gut microbiota. The gut microbiota influences food intake by regulating brain function in a number of ways such as by contributing to the production of neuromodulators such as serotonin which plays an important role in regulating gastrointestinal function.

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