Can the gut microbes of young people make older people feel younger and live longer? Well, we don’t know yet. But it works in fish!

Researchers found that dosing older turquoise killifish with gut microbes from younger killifish made them live 37% longer and increased their activity levels to match the liveliness of younger fish.[1]

Think of it as parabiosis, only using intestinal contents. You know, poop.

Should you care about fish getting younger? Probably. Like humans, killifish have whole ecosystems of beneficial and not-so-friendly microorganisms living in their digestive systems. When these microbes are in balance we feel great, and when they’re out of whack, our performance suffers.

Researchers found that the profile of your microbiome (the ecosystem of microorganisms in your gut) changes as you age.[2] Read on to find out why reversing aging and restoring vitality in fish might matter for humans.

What does gut bacteria do?

Your digestive system houses up to 100 trillion living cells, which protect the lining of your gut and contribute to your immunity.

When your gut microbiome falls out of balance, chaos ensues. You end up tired, weak, ill, and you can end up with inflammation and autoimmune disorders.

Lots of things change the balance of bacteria in your digestive system, such as:

Diet

Exposure to germs

Stress

Weight

Drugs

Alcohol

Age[3]

You can control all of these to a degree, except age. You can’t stop time, but scientists are working on ways to help you stop the symptoms of aging.

Gut microorganisms help you digest your food, and byproduct from the microbes eating your food (yes, it’s bizarre but it works) can be helpful to your system. Around 75% of your vitamin K supply is produced in the intestines by gut bacteria.[4] Gut bacteria also help your body make its own B vitamins and absorb the B vitamins that come from food.

What happens to the gut microbiome as you age

The microbiome profile of infants and young people is radically different from that of older people.[5] It’s a bit of a chicken-and-egg dilemma, as we don’t really know if it’s the age-related habits of the host (that’s you) that changes your gut microbes, or the microbes themselves that cause the changes.

Researchers established that changes in the microbiome modulate some of your aging processes.[6] You can point fingers at gut bacteria for changes in immunity, loss of muscle tone, and declining cognitive function as you age.[7]

Because bacteria are so important to digestion, it may be the change in the way bacteria produce and help you absorb nutrients that cause physical changes associated with aging.[8] We need nutrients to keep our cells young.

Exploring the role of the microbiome is a fast-moving and fascinating area of research that’s only going to get better. Anti-aging therapies such as parabiosis help people feel younger, and hospitals use fecal transplantation therapy (yes, it is what it sounds like) to treat a number of deadly infections and imbalances. It’s absolutely worth examining non-invasive ways to transfer microorganisms from the young and healthy to old or sick people.