Study: Gut microbiome pattern reflects healthy ageing and predicts survival in humans Nature Metabolism, Feb 2021
Overview:
This large study investigated the changes in the gut microbiome of over 9,000 individuals aged 18-87.
Change in the gut microbiome is one aspect of aging that adds to chronic disease and frailty. In people over age 65, recent studies have identified associations between the gut microbiome changes and physical fitness, frailty, and metabolism. Interestingly, studies on centenarians (age 100+) show specific alterations to the gut microbiome including increases in rare gut bacteria and decreases in normal gut residents such as Bacteroides. This has been shown worldwide; thus not as likely due to diet in one location.
When comparing centenarians to other older individuals a pattern emerges showing that higher levels of Bacteroides are associated with a decreased survival.
This study looked at the gut microbiome information for about 9,000 individuals over a wide age range. The researchers took into account the differences in the sampling methods (a couple of different companies were involved). In addition to the different bacterial species, the study also included different metabolites produced from the bacteria. This could be an important difference because our gut microbiome produces both beneficial (e.g. vitamin K) and negative (e.g. TMAO) molecules.
The study found a correlation between maintaining the core microbiome of Bacteroides and Prevotella in aging and the 4-year mortality rate. In elderly individuals, a shift away from the core microbes into a more unique microbiome was associated with better health. This is backed up by the research showing that centenarians have a reduction in these core microbes and a shift towards more uniqueness in their microbiome.
This research doesn’t point to a specific microbe – or a specific probiotic – as the key to longevity, but rather it points to multiple different gut microbes being important to individuals.
What seems to be more important than individual bacterial species is the metabolites produced. Blood levels of phenylacetylglutamine, a metabolite produced by certain bacteria, predicted uniqueness in the microbiome. Additionally, the study also pinpointed tryptophan-derived indole metabolites as also being important. These indole metabolites are important in mediating inflammation.
The study concludes: “In the current analyses, we have expanded the investigation of the gut microbiome in ageing to cover most of the adult lifespan in multiple, large, deeply phenotyped cohorts. Although it is evident from previous research that gut microbiomes of older individuals (65+ years) change with deteriorating health, we propose that gut microbiomes of healthy individuals continue to develop along a distinct trajectory. This trajectory originates in adulthood, is accompanied by a rise in specific plasma microbial metabolites, reflects a healthy ageing phenotype and is predictive of extended survival in the latest decades of human life.”