Gut microbes have some level of influence over the pace of natural aging. It isn’t yet clear as to how large this influence might be, but it may well turn out to be of a similar magnitude to that of exercise. Identifying the most important mechanisms by which the microbiota of the gut affect aging is an ongoing process, still in its comparatively early stages. Many researchers are, quite reasonably, focused on inflammation as a primary concern. Inflammation rises with age, and accelerates the development of all of the common age-related conditions. Scientists are thus attempting to trace back the ways in which different bacterial populations and byproducts can spur the immune system into inappropriate chronic inflammation, and link those mechanisms with known dietary changes and bacterial population changes that take place in later life.
As mammals age, immune cells in the brain known as microglia become chronically inflamed. In this state, they produce chemicals known to impair cognitive and motor function. That’s one explanation for why memory fades and other brain functions decline during old age. Dietary fiber promotes the growth of good bacteria in the gut. When these bacteria digest fiber, they