Sonnenburg Erica - The good gut: taking control of your weight, your mood, and your long-term health

ANDREW WEIL, MD

In medical school in the mid-1960s I learned that the human colon contained a great many bacteria necessary for proper digestion and the assimilation of nutrients and that prolonged use of antibiotics could cause intestinal disturbances as a result of the overgrowth of undesirable organisms. In that era, people who ate yogurt for digestive health or took acidophilus supplements were labeled health nuts, and few medical authorities believed that gut flora had any influence outside of the gastrointestinal tract. There was no concept of a human microbiome that comprised all the microorganisms in and on the body, whose total DNA content was greater than that of human DNA.

Today, research on the human microbiome is one of the hottest areas of medical science, heralding a true revolution in our understanding of physiology and offering great promise for optimizing health and managing disease in novel ways. The species of bacteria and fungi that colonize the gut may determine our interactions with the environment, protecting us from or predisposing us to the development of allergy and autoimmunity. They may protect us from or predispose us to becoming obese or diabetic. They may inhibit or intensify inflammation in the body. They may interact with artificial sweeteners to cause insulin resistance and weight gain in some individuals. They may even influence mental function and emotional wellness.

I first heard about this new view of the microbiome from one of the authors of this book, Justin Sonnenburg. He and his wife, Erica, are prominent researchers in the field, directing their own lab in the Department of Microbiology and Immunology at Stanford University School of Medicine. In 2013, I had invited Justin to give a plenary talk on his research at the 10 th Annual Nutrition and Health Conference, organized by the University of Arizona Center for Integrative Medicine. The conference took place in Seattle and was attended by hundreds of physicians, registered dieticians, and other health professionals. Justins talk was the highlight of the event for me. It conveyed the excitement of discoveries about the human microbiome and suggested answers to puzzling questions I had about health conditions that are on the rise.

Asthma, allergies, and autoimmunity have all increased in North America and other developed areas of the world. Why is the incidence of peanut allergy so much greater today than it was when I grew up in the 1950s? And what is the explanation for the spectacular increase in gluten sensitivity?

That last question had bothered me greatly. Granted that gluten intolerance is a patient-driven diagnosis for which objective tests are lacking, there are still more and more people whose symptoms resolve when gluten is removed from their diet and reappear when it is added back. I reject the notion that grains in general and wheat in particular are bad foods, and I am unconvinced by the argument that the genetics of wheat have changed enough in recent years to be the cause. Gluten sensitivity seems to be most prominent in the North American population. In China, where isolated gluten is served at most restaurantsin such dishes as gluten with black bean sauce, and sweet-and-sour glutensensitivity to this protein is unknown, as it is in Japan. What has changed in North America that might explain it?

Justin Sonnenburg gave me the insight that alterations in our microbiome are likely to blame. Four factors have greatly changed gut flora in individuals in our population over the past few decades. They are: 1) increasing consumption of industrialized, processed foods, 2) widespread use of antibiotics, 3) the alarming rise in Caesarean deliveries, now accounting for one in every three births, and 4) the decline in breast-feeding. In this book you will learn how each of these has contributed to drastic alterations in the human microbiome and how those alterations may account for the increasing incidence of diverse chronic health conditions including autism, depression, and other mental/emotional disturbances.

The Sonnenburgs also discuss possibilities for typing the microbiome as a new diagnostic modality, and they examine the very important question of whether (and how) we might modify our microbiome to reduce disease risks and optimize health. How to do so is a very individual question, and the answer changes as you age. Should you take probiotic dietary supplements? Do they work? Which ones are most effective? What about fermented foods, so prominent in the diets of East Asians? (I believe we should be making and eating more of them.) This book tells you how to tackle all of these questions.

I consider this work essential reading for all health professionals and for everyone interested in a broader understanding of health and wellness. I am sure that you will come away from it with the same excitement that the authors and I feel over these new discoveries about the microorganisms that are so much a part of us.

Tucson, Arizona

October 2014