People whose gut bacteria transformed over the decades tended to be healthier and live longer. By Anahad O’ Connor. NYTimes Health / 03/18/2021
The secret to successful aging may lie in part in your gut, according to a new report. The study found that it may be possible to predict your likelihood of living a long and healthy life by analyzing the trillions of bacteria, viruses and fungi that inhabit your intestinal tract.
The new research, published in the journal Nature Metabolism, found that as people get older, the composition of this complex community of microbes, collectively known as the gut microbiome, tends to change. And the greater the change, the better, it appears.
In healthy people, the kinds of microbes that dominate the gut in early adulthood make up a smaller and smaller proportion of the microbiome over the ensuing decades, while the percentage of other, less prevalent species rises. But in people who are less healthy, the study found, the opposite occurs: The composition of their microbiomes remains relatively static and they tend to die earlier.
The new findings suggest that a gut microbiome that continually transforms as you get older is a sign of healthy aging, said a co-author of the study, Sean Gibbons, a microbiome specialist and assistant professor at the Institute for Systems Biology in Seattle, a nonprofit biomedical research organization.
A lot of aging research is obsessed with returning people to a younger state or turning back the clock,” he said. “But here the conclusion is very different. Maybe a microbiome that’s healthy for a 20-year-old is not at all healthy for an 80-year-old. It seems that it’s good to have a changing microbiome when you’re old. It means that the bugs that are in your system are adjusting appropriately to an aging body.”
The researchers could not be certain whether changes in the gut microbiome helped to drive healthy aging or vice versa. But they did see signs that what happens in people’s guts may directly improve their health. They found, for example, that people whose microbiomes shifted toward a unique profile as they aged also had higher levels of health-promoting compounds in their blood, including compounds produced by gut microbes that fight chronic disease.
Scientists have suspected for some time that the microbiome plays a role in aging. Studies have found, for example, that people 65 and older who are relatively lean and physically active have a higher abundance of certain microbes in their guts compared to seniors who are less fit and healthy. People who develop early signs of frailty also have less microbial diversity in their guts. By studying the microbiomes of people of all ages, scientists have found patterns that extend across the entire life span. The microbiome undergoes rapid changes as it develops in the first three years of life. Then it remains relatively stable for decades, before gradually undergoing changes in its makeup as people reach midlife, which accelerates into old age in those who are healthy but slows or remains static in people who are less healthy.
Although no two microbiomes are identical, people on average share about 30 percent of their gut bacterial species. A few species that are particularly common and abundant make up a “core” set of gut microbes in all of us, along with smaller amounts of a wide variety of other species that are found in different combinations in every person.
To get a better understanding of what happens in the gut as people age, Dr. Gibbons and his colleagues, including Dr. Tomasz Wilmanski, the lead author of the new study, looked at data on over 9,000 adults who had their microbiomes sequenced. They ranged in age from 18 to 101.