How does your microbiome affect your health and longevity?

People who live to an exceptionally old age have a strikingly different gut flora than younger people. In people aged 105 and older, certain groups of bacteria, including Akkermansia and Bifidobacterium, are more prevalent than in younger age groups. At the same time, as we age, the presence of common, protective bacterial families gradually declines, while less common and sometimes harmful species take their place. These are associations from observational research, not evidence that these bacteria are the cause of a long life.

A large study of more than 9,000 participants showed that healthy people in their eighties and beyond who had an increasingly personal and unique microbiome composition survived better over a four-year period. People who retained a poorly varied microbiome at an advanced age that closely resembled the average had lower survival rates. This finding is also observational: the association may be mediated by healthy lifestyle habits, health status, or other factors.

The gut flora also influences the immune system and inflammation in the body. Disruptions in the gut flora during ageing likely contribute to two negative processes: a blunting of the immune system and a smouldering chronic inflammation that quietly fuels disease in the background. Through metabolic products produced by bacteria, such as TMAO and short-chain fatty acids, the gut flora also influences the risk of cardiovascular disease. This mechanism is biologically plausible, but randomised trials in humans are largely lacking.

Animal research has shown that a gut microbiota transplant from healthy mice to mice with accelerated ageing extended lifespan and improved health. Even the administration of the bacterium Akkermansia muciniphila alone had an effect. Whether this also works in humans is unknown. Clinical applications in humans are still at a very early stage and safety has not been sufficiently studied to recommend this as an anti-ageing strategy.

Probiotics and prebiotics are sometimes suggested as a way to address this, but the evidence for them in humans falls short. There are still too few data on which bacterial strains make a precise difference for which person to give targeted advice. If you want to positively influence your gut flora, lifestyle measures that have broader support, such as a fibre-rich diet and physical activity, are for now the most concrete tools available.