Dietary Fiber, Brain Inflammation, and Aging

Most of people regard fiber as something that helps keep them “regular.” Others who may be more interested in their health understand how a diet rich in fiber can foster populations of beneficial gut flora and greater diversity overall within the microbiome. The latest investigation however is sure to pave the way for a better understanding of the mechanisms linking higher levels of soluble fiber with improved brain health.

The University of Illinois team fed mice of varying ages different levels of dietary fiber from whole food sources and observed dramatic differences in the brains of those mice getting larger amounts of fiber when compared to the older mice that were lacking the fiber. The key to less microglial-based inflammation in some of the older mice was the presence of n-butyrate. N-butyrate is a primary short chain fatty acid that is generated from gut flora metabolizing or essentially fermenting certain types of dietary fiber. Previous studies have shown that at higher levels in circulation, n-butyrate offers protection against heart disease, caner, and other inflammatory-mediated diseases. The n-butyrate levels within the high fiber-fed mice were, as expected, within the highest quartile.

It is widely accepted by neuroscientists that most diseases of the aging brain have major inflammatory components.  Numerous aspects of the modern lifestyle contribute to this inflammation: stress, sleep deprivation, chronic infection, and diet. While there are many dietary factors that we could choose to change in a campaign to reduce the epidemic of Alzheimer’s, dementia, and other diseases associated with aging, eating more fiber would seem to be the easiest. Not all fibers are created equally however. While certain bacteria have an affinity for specific types of fiber, n-butyrate generating microbes prefer vegetable and legume fiber, as opposed to those from grains and/or bran.

If you have not seen a need to evaluate the fiber levels in your diet until now, this may be the reason to do so. Everyone should aim for at least 35 to 50 grams of fiber per day, primarily from an array of vegetables: both starchy and non-starchy. If you do this and choose some sort of fermented food regularly such as yogurt or kimchi, you will be making quite possibly the single most protective lifestyle change that is out there.