The more scientists examine the bacteria in the gut, the clearer its importance for our overall health becomes, and new research links a specific type of development of the gut microbiome to a longer life expectancy and healthier old age.
In a study of more than 9,000 people in three different cohorts, new research found that our intestinal microbiomes become more unique and personalized for us as we age, and that the number of essential bacteria (such as Bacteroides) tend to decrease as well.
This pattern appears to be associated with physical health and longevity as well. Therefore, people whose microbiomes are not continuously changing in old age and who are not seeing a reduction in essential bacteria tend not to be as healthy or to live as long.
“This unique signature can predict the patient’s survival in the last decades of life,” says biochemist Tomasz Wilmanski, of the Institute for Systems Biology (ISB).
“Interestingly, this pattern of exclusivity appears to start in middle age – 40-50 years of age – 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 also can contribute directly to health as we age. “
It was notable that, even when microbiomes diverged in design at older ages, the metabolic functions they performed were consistent among individuals – the researchers found certain metabolites linked to longevity in the gut of people (and several animals) whose microbiomes were following a diet healthier to standardize.
As Wilmanski points out, the question remains whether these changes in the composition of the microbiome are really contributing to good health or just reflecting this, but it is certainly worth further investigation, say the scientists – and adds some clarity to an area of research where the findings were not always clear.
For example, metabolites called indoles have been discovered that were previously associated with reducing inflammation in the intestines of mice – and chronic inflammation is one of the health problems that increase the risk of mortality in older people.
“Previous results in research on the aging of the microbiome 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,” said the microbiologist Sean Gibbons from ISB.
“Our work, which is the first to incorporate a detailed analysis of health and survival, can resolve these inconsistencies.”
Although the study as a whole covered 18- to 101-year-olds, it was a particular cohort of individuals aged 78 to 98 that allowed researchers to take a close look at how microbiomes and mortality may be linked.
We know that it is at the beginning and at the end of our lives when our mixture of intestinal bacteria undergoes the greatest changes, and this latest study confirms the idea that a mixture of abdominal bacteria in continuous evolution at the end of life is a good sign: perhaps an indicator of a body still prosperous in the last years of life.
The study suggests that a healthy gut microbiome – whatever it may be – may not look the same at different stages of life, and this is a useful avenue for future research to explore. It appears that our microbiomes may develop differently in older people, and some of these developments may be healthier than others.
“This is an exciting job that we believe has important clinical implications for monitoring and changing the health of the intestinal microbiome throughout a person’s life,” said ISB bioengineer Nathan Price.
The research was published in Nature’s Metabolism.