According to the 2010 US Census, there were 53,364 centenarians in the US, and in the 2020 Census about 90,000 Americans were centenarians. So around 1.73 of every 10,000 Americans live to be at least 100 years old, making it relatively rare for a person to reach that age. The rate in Japan, with the highest rate of centenarians, is about 3.43 centenarians per 10,000 people. Most people want to know what the secret to a long life is, and there have been multiple studies on the topic. Even in the Guinness Book of World Records, where the longest-lived people are listed, it also includes their 'secrets.'
Now, researchers have suggested that the right combination of microbes in the gut might help people live a longer life. Reporting in Nature Microbiology, scientists assessed the microbiomes of 176 healthy Japanese centenarians, but rather than focusing only on bacteria, they looked at viruses, or the gut viriome. The work showed that the gut viriome of centenarians is not only more diverse than the gut viriomes of younger adults who were over age 18 and older adults over the age of 60, it also carries unusual microbes.
Previous studies have indicated that older Japanese citizens carry gut bacteria that generate new molecules that confer resistance to pathogens. This improved shield against infection can help explain why they live longer than other people, suggested first study author and postdoctoral researcher Joachim Johansen of the University of Copenhagen.
Many viruses called bacteriophages only infect bacterial cells, and they can have a huge impact on the composition of the gut microbiome. Japanese centenarians were found to carry unique microbiomes. There was a great deal of diversity in both the bacteria and viruses that were in centenarian guts, noted the authors.
"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," noted Johansen.
There is still a lot left to learn but we may be able to use the gut microbiome to help improve healthspan, longevity, or protect against disease.
"We want to understand the dynamics of the intestinal flora. How do the different kinds of bacteria and viruses interact? How can we engineer a microbiome that can help us live healthy, long lives? Are some bacteria better than others? Using the algorithm, we are able to describe the balance between viruses and bacteria," said senior study author Associate Professor Simon Rasmusseny.
The investigators identified viruses in the centenarians' guts that carried genes that actually promoted the bacteria, and encouraged the metabolism of certain molecules. This could have a stabilizing influence on the microbiome that tamps down inflammation, Johansen suggested.
After discovering the beneficial microbes, an obvious question is what proportion of people are carrying them, and can we get them into people who might not have them, but could benefit, added Rasmussen. The microbiome could present a much easier way to improve health than through the manipulation of genes, so researchers will be following up on this work.