India, Dec. 17 -- Scroll through social media and you will be told that your gut is broken and that a capsule can fix it. Probiotics promise balance. Prebiotics promise strength. Influencers promise immunity, clarity, and longevity. The pitch rests on a simple idea that science already knows what a healthy gut microbiome looks like.

It does not. At least, not in the way you have been led to believe.

For years, microbiome research leaned on small, scattered studies. A few dozen people here, a few snapshots there. Patterns were teased out, amplified, and sold back as certainty. The gut became a marketing ploy long before it became a mapped system.

That has begun to change. A new study published in Nature has now looked at gut DNA from ov...