Identifies the role of intestinal bacteria in brain health, outlining easy-to-follow dietary strategies for preserving later-in-life brain functions by improving gut ecology. Perlmutter explains the potent interplay between intestinal microbes and the brain. He describes how the microbiome develops from birth and evolves based on lifestyle choices, how it can become 'sick,' and how nurturing gut health through a few easy strategies can alter your brain's destiny for the better.