Make-up of gut microbes linked to aging and longevity in humans

A study published in 2021 links gut microbiome uniqueness to healthy aging and longevity. The human gut is home to trillions of microorganisms that are known to play an important role in health. Imbalance of healthy and unhealthy microbes may lead to diseases such as gastrointestinal disorders, allergies, central nervous system illnesses, and obesity. Scientists are also beginning to understand how age-related changes of microbiomes affect host physiology. Several studies have already shown a higher species diversity in centenarians compared to younger individuals, suggesting that gut microbiomes continue to develop in host humans even in the latest decades of life. The extensive ELDERMET research on older Irish adults reported differences in bacterial colonies in people over 65 years old compared to younger, healthy controls. Other studies have demonstrated a gradual change in microbiome composition in residents of long-term care facilities. While these recent studies demonstrated a link between the composition of gut microbiomes and long-term health outcomes, they lacked enough data to produce conclusively findings. The new study was conducted by researchers from the Institute for Systems Biology. Thousands of participants between the ages of 18 and 101 years old were scrutinized as scientists investigated how gut microbial aging patterns across the adult human lifespan corresponded to health and survival in the latter decades of life. Stool samples were analyzed over time to measure the ‘uniqueness’ of the gut microbiome pattern in each individual. The researchers established that gut microbiome composition became increasingly unique starting at the ages of 40 – 50 years and continued to increase thereafter. Age was found to have the strongest association with microbiome uniqueness. In later decades of human lifespan, healthy individuals continued to show an increasingly unique composition of gut microbiome. This pattern was however absent in individuals who demonstrated worse health. Through the study’s four-year follow-up, it was also established that mortality risk decreased in individuals with more unique gut microbiomes. Interestingly, self-reported dietary habits, demographics, lifestyle, and health measures seemed to have no impact microbiome uniqueness. Women’s microbiomes were found to be more unique with age, which makes sense given that women have an extended lifespan compared to men. Researchers concluded that healthy aging of the gut microbiome involves depletion of core microbes and their replacement by less common groups. In other words, the gut microbiomes of healthy individuals continue to develop throughout aging. It is the lack of this development that appears to be linked to worse health outcomes. The outcomes of this study have important implications for the world’s aging population. As scientists continue to understand how microbiomes change with age, it may be possible to identify modifiable interventions that can promote healthier aging and longevity.