South Asian Gut Microbiome :

Why in News?

A major three-year study published in the scientific journal Gut Microbes has created the first-ever reference database of the gut microbiome across South Asia. Led by researchers from India and the US, the study reveals that changes in the gut bacteria of urbanizing Indians—driven by processed foods rather than genetics—help explain the rapid rise in lifestyle diseases like diabetes, obesity, and hypertension.

What is a Gut Microbiome?

A gut microbiome refers to the trillions of microscopic organisms (mostly helpful bacteria, but also fungi and viruses) that live naturally inside your digestive tract, primarily in your large intestine.

• The “Second Brain” or Inner Ecosystem: Think of your gut as a bustling internal city. Far from just digesting food, these microbes help train your immune system, produce essential vitamins, regulate metabolism, and even communicate with your brain.

• Why it Matters: A balanced, diverse microbiome keeps you healthy. However, when bad bacteria take over due to poor diet or lifestyle, it can lead to inflammation, weight gain, and chronic illnesses.

Key Points from the Study:

• The “Natural Experiment” in India: India provides a rare setting where rural and urban populations share the same family ancestry and genetics, but eat vastly different diets. This allowed researchers to prove that diet changes—not genes—reshape our gut bacteria.

• Rise of Harmful Bacteria (Megamonas): Researchers found that people living in cities have a much higher abundance of a bacterium called Megamonas, which is globally linked to obesity, high blood pressure, and high blood sugar.

• Loss of Protective Bacteria (Holdemanella): Traditional rural diets rich in fiber support beneficial bacteria like Holdemanella (which helps control blood sugar). These protective bacteria are largely lost when people move to cities and eat processed foods—except in places like Kerala, where families maintained traditional diets even after migrating.

• Processed Food is the Culprit: Scientists noted that the shift is caused by ultra-processed foods (packaged snacks, biscuits, sugary soft drinks, and fast food) rather than natural foods.

• Next Steps: The research team is now analyzing the specific molecules produced by these bacteria to directly connect individual microbes to specific diseases.