Bacteria-eating viruses in the gut may help us live to a healthy 100

We’re all told that to live longer, we must exercise regularly, eat a healthy diet, get enough sleep, maintain an optimal weight, not smoke, and manage stress. But why do some people naturally make it to the ripe old age of 100 while remaining healthy? A new study may have an answer to that question, and the bottom line is that it has to do with what’s in our gut.

Over the years, studies have shown that the gut microbiome, billions of bacteria and other microorganisms that live in our intestinal tract and are both helpful and potentially harmful, has been linked to mood, memory, body weight, and disease.

While these studies have told us a lot about how gut bacteria affect health, the viruses that make up the microbiome – the gut virome – are less commonly explored. Researchers from the University of Copenhagen studied the virome of 176 healthy Japanese centenarians to see if they could discover what it was about bacteriophages, viruses that eat bacteria, that enabled these people to maintain good health at such an advanced age.

“Our intestines contain billions of viruses living off and inside bacteria, and they could not care less about human cells; instead, they infect the bacterial cells,” said Simon Rasmussen, a corresponding author of the study. “And seeing as there are hundreds of different types of bacteria in our intestines, there are also lots of bacterial viruses.”

Using an algorithm they designed, the researchers mapped the intestinal bacteria and bacteriophages of the centenarians. Compared with adults over 18 and those over 60, they found that the centenarians had a more diverse and rich gut virome, as well as diverse bacteria.

“We found great biological diversity in both bacteria and viruses in the centenarians,” said Joachim Johansen, lead author of the study. “High microbial diversity is usually associated with a healthy gut microbiome. And we expect people with a healthy gut microbiome to be better protected against aging-related diseases.”

Their study suggests that bacteria-infecting viruses might strengthen the bacteria they interact with, positively affecting health.

“We have learned that if a virus pays a bacterium a visit, it may actually strengthen the bacterium,” Johansen said. “The viruses we found in the healthy Japanese centenarians contained extra genes that could boost the bacteria. We learned that they were able to boost the transformation of specific molecules in the intestines, which might serve to stabilize the intestinal flora and counteract inflammation.”

The researchers say their findings may help us understand what specific bacteria and viruses we should optimize to protect the body against disease.

“If you discover bacteria and viruses that have a positive effect on the human intestinal flora, the obvious next step is to find out whether only some or all of us have them,” said Rasmussen. “If we are able to get these bacteria and their viruses to move in with the people who do not have them, more people could benefit from them.”

That the microbiome can actively be changed is significant, say the researchers.

“Intestinal bacteria are a natural part of the human body and of our natural environment,” said Rasmussen. “And the crazy thing is that we can actually change the composition of intestinal bacteria. We cannot change the genes – at least not for a long time to come. If we know why viruses and intestinal bacteria are a good match, it will be a lot easier for us to change something that actually affects our health.”

The study was published in the journal Nature Microbiology.

Source: University of Copenhagen via EurekAlert!

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