SEATTLE – Living a long and healthy life depends on the unique combination of bacteria in our gut, according to a new study. Patterns in a person’s microbiome – the organisms that live in the gut – can determine whether a person will age well or die early, scientists say.
The intestine mainly contains healthy bacteria and immune cells, which help to prevent infections and diseases. Although it is a vital component of the body’s immune system, its importance in the aging process is still unclear. Now, researchers at the Institute for Systems Biology in the United States show that the intestinal microbiome continues to evolve, but only among healthy people.
“Previous results in the microbiome aging survey seem inconsistent, with some reports showing a decline in central intestinal genera in centuries-old populations, while others show relative stability of the microbiome until the beginning of declines related to aging in health,” says the co- author Dr. Sean Gibbons in a statement. “Our work, which is the first to incorporate a detailed analysis of health and survival, can resolve these inconsistencies. Specifically, we show two distinct aging trajectories. One, a decline in central microbes and a concomitant increase in uniqueness in healthier individuals, consistent with previous results in centenarians living in the community, and two, the maintenance of central microbes in less healthy individuals. “
The researchers analyzed the intestinal microbiome of 9,000 people aged 18 to 101 years for the study. In particular, the team followed the survival rates of a cohort of 900 elderly people aged 78 to 98.
Their work shows that the intestinal microbiome has become increasingly exclusive as participants get older. Central bacteria, known as bacteriodes and common to all humans, begin to decline in middle to late adulthood.
“Interestingly, this pattern of exclusivity seems to start in middle age – 40 to 50 years old – and is associated with a clear blood metabolomic signature, suggesting that these changes in the microbiome may not simply be diagnoses of healthy aging, but they may also contribute directly to health as we age, ”says study co-author Dr. Tomasz Wilmanski. “For example, indoles are known to reduce inflammation in the intestine, and chronic inflammation is considered to be a major driver of the progression of aging-related morbidities.”
Despite its increasing uniqueness, the healthy microbiome continued to share common traits. People with unique intestinal patterns had different substances in their blood plasma, known as metabolites, the study shows. This includes indole derived from tryptophan, which has been shown to prolong the life of mice.
Another metabolite, Phenylacetylglutamine, had already been found in large quantities in the blood of centenarians. But that unique transformation occurred only among healthy individuals, the researchers say.
“This unique signature can predict the patient’s survival in the last decades of life,” says Dr. Tomasz Wilmanski. “Healthy individuals around the age of 80 showed a continuous microbial tendency towards a unique state of composition, but that trend was absent in less healthy individuals.”
The fact that the microbiome continues to develop later in healthy individuals may have important clinical implications, say the researchers. “This is a stimulating work that we believe has important clinical implications for monitoring and modifying the health of the intestinal microbiome throughout a person’s life,” adds co-author Dr. Nathan Price.
The results are published in the journal Nature’s Metabolism.
SWNS writer Tom Campbell contributed to this report.