It is known that there are relationships between gut bacteria and aging in many species, though exploration of the details is still at a comparatively early stage. Even without delving into the literature one can imagine numerous possibilities by which these bacteria influence long-term health, such as by playing a role in the degree to which food is converted into nutrients useful for cells, or by interacting with the immune system. Here, researchers examine age-related changes in gut bacteria in flies. The health of the intestine is particularly important in fly aging, much more so than in higher species, so we should probably wait for similar experiments to be conducted in mammals before drawing conclusions:
Why do some people remain healthy into their 80s and beyond, while others age faster and suffer serious diseases decades earlier? A new study suggests that analyzing intestinal bacteria could be a promising way to predict health outcomes as we age. The researchers discovered changes within intestinal microbes that precede and predict the death of fruit flies. "Age-onset decline is very tightly linked to changes within the community of gut microbes. With age, the number of bacterial cells increase substantially and the composition of bacterial groups changes."
In a previous study, the researchers discovered that five or six days before flies died, their intestinal tracts became more permeable and started leaking. When a fruit fly's intestine begins to leak, its immune response increases substantially and chronically throughout its body. Chronic immune activation is linked with age-related diseases in people as well. In the latest research, which analyzed more than 10,000 female flies, the scientists found that they were able to detect bacterial changes in the intestine before the leaking began. As part of the study, some fruit flies were given antibiotics that significantly reduce bacterial levels in the intestine; the study found that the antibiotics prevented the age-related increase in bacteria levels and improved intestinal function during aging.
The biologists also showed that reducing bacterial levels in old flies can significantly prolong their life span. "When we prevented the changes in the intestinal microbiota that were linked to the flies' imminent death by feeding them antibiotics, we dramatically extended their lives and improved their health." Flies with leaky intestines that were given antibiotics lived an average of 20 days after the leaking began - a substantial part of the animal's life span. On average, flies with leaky intestines that did not receive antibiotics died within a week.