Gut microbiota is linked to several diseases, affecting a range of areas of the body, from the gut to the brain. It also has connections with pregnancy and plays a role in the lives of both newborns and children. Little, however, is known about gut microbiome variation during aging. And finding a common pattern in the gut microbiota of aging individuals could be a useful tool to predict health outcomes and life expectancy.
In an attempt to trace a pattern in the gut microbiota of aging individuals who are in good health, Dr Orwoll, Dr Price and their respective teams analyzed the gut microbiota of individuals in different age groups. Researchers recruited 4,582 individuals aged between 18 and 98 and analyzed their fecal microbiome. They used statistical models to find a pattern in microbiome shifts among healthy aging individuals and crossed the data with factors such as body mass index, sex, age, diet and health care to find associations.
First, Wilmanski et al.’s study showed that the pattern identified in the gut microbiome of healthy aging individuals lies in the concept of uniqueness. Microbiome uniqueness is how distinct the gut microbiome is from everyone else’s in the studied population. Microbiome uniqueness was strongly linked to age, lower body mass index, higher omega 3, a higher ratio for ‘good’ cholesterol versus ‘bad’ cholesterol, higher vitamin D and lower triglycerides. That meant a healthy aging individual had a more unique microbiome than a non-healthy subject.
In a second part, the researchers found that microbiome uniqueness increased with age in both sexes, but was more pronounced in women, indicating that women’s microbiomes become unique more quickly with age. This may explain why women live longer than men.
When undertaking a more precise analysis of microbiome uniqueness, researchers noticed that individuals approaching 85 years of age and older with a high abundance of Bacteroides and a low gut microbiome uniqueness score had decreased survival in a 4 year follow-up. Therefore, the rarer and more unique the bacteria composing the gut microbiota of aging individuals, the more likely they will be healthy.
The often contradictory findings in elderly and centenarian populations indicate that multiple gut microbiome patterns of aging may exist. Finding a single bacterium responsible for health outcomes when aging remains a challenge, however, as gut microbiota variations differ around the world due to cultural habits and traditional food. As a result, gut microbiome uniqueness could be an intriguing new diagnostic tool for healthy aging.
Wilmanski, T., Diener, C., Rappaport, N. et al. Gut microbiome pattern reflects healthy ageing and predicts survival in humans. Nat Metab 3, 274–286 (2021). doi.org/10.1038/s42255-021-00348-0