In order to understand the benefits of food for health, we need a new definition of health. To most people, health is the absence of disease. But it is much more than that. In fact, the definition of health needs a major upgrade.

Our health is an active state, protected by a series of remarkable defense systems in the body that are firing on all cylinders, from birth to our last day alive, keeping our cells and organs functioning smoothly. These health defense systems are hardwired in our body to protect us. Some are so powerful they can even reverse diseases like cancer. And while they function as separate systems of defense, they also support and interact with one another. These defense systems are the common denominators of health. Each of the systems is influenced by diet. When you know what to eat to support each health defense, you know how to use your diet to maintain health and beat disease.

When I teach other doctors and students about diet and health, I use the analogy that the body is like a medieval fortress, protected not only by its stone walls, but by a host of other clever built-in defenses. Think of your health defense systems as the hidden defenses of the body fortress. These defenses heal the body from within, so it is now possible to systematically examine how to shore up your health.

The five defense systems are angiogenesis, regeneration, microbiome, DNA protection, and immunity. Here is what they can do:

Angiogenesis: The process by which these blood vessels are formed. Foods like soy, green tea, coffee, tomatoes, red wine, beer, and even hard cheese can influence the angiogenesis defense system.

Regeneration: Powered by more than 750,000 stem cells distributed throughout our bone marrow, lungs, liver, and almost all of our organs, our body maintain, repair, and regenerate throughout our lives. Some foods like dark chocolate, black tea, and beer can mobilize them and help us regenerate. Other foods, like purple potatoes, can kill deadly stem cells that spark cancer growth.

Microbiome: Almost 40 trillion bacteria inhabit our bodies that control our immune system, influence angiogenesis, and even help produce hormones that influence our brain and social function. We can boost our microbiome by eating foods like kimchi, sauerkraut, cheddar cheese, and sourdough bread.

DNA Protection: Our DNA is our genetic blueprint, but it is also designed to be a defense system. It has surprising repair mechanisms that protect us against damage caused by solar radiation, household chemicals, stress, compromised sleep, and poor diet, among other insults. Not only can certain foods prompt DNA to fix itself, but some foods turn on helpful genes and turn off harmful ones, while other foods lengthen our telomeres, which protect DNA and slow aging.

Immunity: Our immune system defends our health in sophisticated ways that are much more complicated than we previously thought. It is influenced by our gut, and it can be manipulated to successfully attack and wipe out cancer, even in the elderly. Recent discoveries have completely changed our understanding of the immune system. Foods like blackberries, walnuts, and pomegranate can activate the immune system, while other foods can dampen its activities and help reduce the symptoms of autoimmune diseases.

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There is no “silver bullet” for any one disease or for overall health and longevity. No single factor in our life is going to prevent sickness. But my research shows we have something even better. There is a way to boost our own defense systems, so the body will heal itself. These revelations tell us that we have radically underestimated our power to transform and restore our own health.

If your goal is to extend the number of healthy years you have ahead, your food choices can tip the odds in your favor. By boosting your defense systems, you’ll have a better shot at beating back disease and extending not just the length but also the quality of your life.

We live in a time of enormous and exciting scientific progress, so good health should be within reach of most everyone. And yet millions suffer and die from avoidable chronic illnesses, even as more high-tech treatments are invented. The crushing cost of medical care continues to rise, creating a precarious situation where the entire system of modern medicine is on the brink of collapse. The only way to comprehensively bring down the cost of health care is to decrease the number of people who are sick.

We each need to do our part, and the best way to make the world a healthier place is to start with the choices you make for yourself and the people you care about. Let go of the idea that health is the absence of disease and start eating to beat disease every day. Bonne santé, and bon appétit.

Excerpted from EAT TO BEAT DISEASE: The New Science of How Your Body Can Heal Itself. Copyright © 2019 by William W. Li, MD. Reprinted with permission of Grand Central Publishing. All rights reserved.


  • William W. Li, MD, is an internationally renowned medical doctor, researcher, and president and a founder of the Angiogenesis Foundation. His groundbreaking work has led to the development of more than 30 new medical treatments, has impacted more than 50 million people worldwide, and covers more than 70 diseases including cancer, diabetes, blindness, heart disease, and obesity. His TED Talk, “Can We Eat to Starve Cancer?” has garnered more than 11 million views. Dr. Li has appeared on The Dr. Oz Show, CNN, and MSNBC and has been featured in USA Today, TIME, The Atlantic, and O Magazine.  Dr. Li has served on the faculty of Harvard Medical School, and presented at the Vatican’s Unite to Cure conference.