Dr. David Perlmutter, a board-certified neurologist and recipient of the Linus Pauling Award for his innovative approaches to addressing neurological disorders, has recently released Brain Maker, the latest in a series of books on brain health. This medical advisor to the Dr. Oz Show demonstrates how brain problems can be prevented by adopting lifestyle changes that nurture the bacteria living in the digestive system.

Why did you begin your book with the quote, “Death begins in the colon,” rather than “Brain health begins in the gut”?

I wanted to draw attention to the real life-or-death issues mediated by what goes on inside the gut. Individuals with an immediate concern for their heart, bones, immune system or brain must recognize that the health of these parts and functions are governed at the level of commensal gut bacteria, the normal microflora that eat what we eat. This relationship is the most powerful leverage point we have for maintaining health.

How were you led to expand from studying the nervous system and brain to investigating gastrointestinal medicine?

Early on in my career, I was taught that everything that goes on in the brain stays there. But leading-edge research now reveals that seemingly disparate organs are in close communication, regulating each other’s health. As scientific literature began supporting the notion that gut-related issues have a huge bearing on brain health, and specifically on brain disease, it became important to me to be able to leverage deep knowledge of this empowering information in terms of being able to treat brain disorders.

What is the Human Microbiome Project (HMP)?

HMP, launched in 2008 by the National Institutes of Health, is a $115 million exploration of the gut microbiome. In the ongoing research project involving genetic and DNA assessment, researchers are looking at the microbiome array in the gut of individuals suffering from various diseases. They are drawing correlations between emerging patterns in the abnormalities of gut bacteria and specific diseases. For example, autism correlates with an overabundance of the Clostridia species. In diabetes, there are more Firmicutes than Bacteroidetes, which we also see in obesity characteristic of the Western cosmopolitan diet.

This is paving the way for interventions designed to restore a normal balance of gut bacteria. An  example in my book is Dr. Max Nieuwdorp’s research at the University of Amsterdam, in which he discovered an array of abnormal bacteria that characterize Type 2 diabetes. In the more than 250 individuals diagnosed with diabetes that he treated in a double-blind study, he was able to reverse the disease by inserting a series of fecal material transfers from healthy, lean donors into diabetic patients.

What is the most eye-opening information about the roles played by gut organisms?

More than 100 trillion bacteria live in our gut. Plus, there are viruses, yeast species and protozoa. When we factor in their genetic material, it means that an astonishing 99 percent of the DNA in our body is bacterial. It’s humbling to realize they influence all manner of physiology, from our immune system to our metabolism, making vitamins, maintaining the gut lining and controlling inflammation, the key mechanism involved in Alzheimer’s, Parkinson’s, multiple sclerosis and any number of brain degenerative disorders. They also exert influence over the expression of our 23,000 genes, in effect regulating the expression of the human genome.

The latest startling discovery—which is so new that it’s not in the book—is that bacterial DNA sequences have now been found in the human genome, meaning we are partly bacterial. It reveals the most sophisticated symbiotic and intimate relationship at the deepest level imaginable. It turns the previous way of thinking about who we are upside-down. Our perceptions of the world, moods, hunger or satiety, even our metabolism, are dictated by gut bacteria, which deserve careful stewarding. They don’t deserve, for example, to be bombarded by the capricious use of antibiotics whenever we have the sniffles.

How can we reestablish good gut health?

Better food choices bring about significant changes in our body’s microbiome. By incorporating prebiotic foods such as Jerusalem artichokes, dandelion greens, garlic, leeks, onions, jicama or Mexican yam, as well as fermented foods such as kimchi, kombucha tea, yogurt and kefir, individuals can reestablish good gut health that helps them gain control over inflammation, the cornerstone of all degenerative conditions. Inflammation originates in the gut. Balancing bacteria and reducing intestinal permeability, which allows substances to leak through the lining of the small intestine into the bloodstream, can reduce it.

Linda Sechrist is a Natural Awakenings senior staff writer.