People whose gut bacteria transformed over the decades tended to be healthier and live longer. The human microbiome consists of the 10-100 trillion symbiotic microbial cells harbored by each person, primarily bacteria in the gut; the human microbiome consists of the genes these cells harbor.
A lot of aging research is obsessed with returning people to a younger state or turning back the clock. But here the conclusion is very different. Maybe a microbiome that’s healthy for a 20-year-old is not at all healthy for an 80-year-old. It seems that it’s good to have a changing microbiome when you’re old. It means that the bugs that are in your system are adjusting appropriately to an aging body.
Researchers can not be certain whether changes in the gut microbiome helped to drive healthy aging or vice versa. But they did see signs that what happens in people’s guts may directly improve their health. They found, for example, that people whose microbiomes shifted toward a unique profile as they aged also had higher levels of health-promoting compounds in their blood, including compounds produced by gut microbes that fight chronic disease.
People who have the most changes in their microbial compositions tended to have better health and longer life spans. They had higher vitamin D levels and lower levels of LDL cholesterol and triglycerides, a type of fat in the blood. They needed fewer medications, and they had better physical health, with faster walking speeds and greater mobility.