What is the microbiome?
The microbiome is the community of trillions of bacteria and other microbes living in and on your body, especially in your gut, that help digest food, train your immune system and make useful compounds.
Think of your gut microbiome as a rainforest inside you. A rich, diverse rainforest is resilient and productive; a forest reduced to a few species is fragile and easily overrun by weeds.
Why it matters for aging
Your gut microbes break down fiber you can't digest, producing short-chain fatty acids that nourish the gut lining and calm inflammation. They also convert plant compounds into active molecules and help keep harmful bacteria in check.
With age, the microbiome often becomes less diverse. An unbalanced microbiome, called dysbiosis, is one of the twelve hallmarks of aging. The best-supported way to support it is a diet rich in varied plants and fiber.
A common myth
Bacteria in your body are germs, and fewer is better.
Most of your gut microbes are helpful or harmless. A diverse microbiome is linked to better health, and many plant compounds only work after gut bacteria transform them, like urolithin A from pomegranates.
Go deeper
Deep dives
- Does urolithin A work? What the human trials actually show
- Triphala: the three-fruit formula, tested
- Ayurveda and longevity: what science says about the ancient system
Related terms
Updated Nov 9, 2026 · All terms