part0011

The Body’s Defense Systems Against Disease

Dr. Li presents the concept of health as an active state protected by the complex interaction of the five major defense systems: angiogenesis, cell regeneration, microbiome health, DNA protection, and the immune system. In his book, he presents an in-depth analysis of research on each of these topics. As with all bodily systems, these defense systems work synergistically.

For the purposes of this book, I’ll provide an overview of each system, explain what happens when one is not working correctly, and highlight the foods that provide the greatest benefits within each system.

Simply put, angiogenesis is the process of blood vessel formation. Angiogenesis is important because the body has a natural ability to regulate when and where new blood vessels are produced in order to increase or decrease the blood supply to various parts of the body as needed. This system plays a critical role in maintaining healthy tissue, healing damaged tissue, and preventing the growth and spread of potential cancer cells.

Disease can result from excessive angiogenesis, which is when blood vessels feed diseased tissue or cancerous tumors, and insufficient angiogenesis, which is when there aren’t enough blood vessels to supply healthy tissue with the blood and nutrients it needs to survive.

Excessive angiogenesis can lead to blindness from age-related macular degeneration and diabetes-related vision loss (Penn et al. 2008). There is also evidence that too much angiogenesis can lead to the worsening of rheumatoid arthritis, an autoimmune disease that causes inflammation in the joints (Bousseau et al. 2018). Medications that inhibit excessive angiogenesis are now a common type of cancer therapy (Saeed et al. 2019).

Diabetes is a disease that can cause insufficient angiogenesis, which can reduce the blood supply to nerves when blood sugar is not properly controlled. Lack of angiogenesis can also cause chronic wounds and subsequent infections because inadequate blood flow to the affected area impedes healing (Okonkwo and DiPietro 2017).

Well-balanced angiogenesis is essential for preserving health and preventing disease. It is necessary for getting proper blood supply to organs like your brain and heart, even helping the body naturally work around blockages through new blood vessel formation (Potz et al. 2017). It is equally important in cutting off the fuel supply that cancer cells need for rapid growth.

Luckily, the foods we eat can help prevent or slow chronic diseases that are caused by both excessive and insufficient angiogenesis. Many foods can help the body regulate this defense system to optimize proper blood flow while stopping blood vessels from forming abnormally to feed diseased tissue or cause other damage. Whether you’re eating angiogenic (blood vessel–forming) or antiangiogenic (blood vessel–regulating) foods, you’ll improve your overall health. Specific foods that can help the body manage angiogenesis include soy, tomatoes, green tea, kale, and pomegranates, among many others that you can find on Your Eat to Beat Disease Food List (here ).

Soy?! Yes, Soy

Some people may be surprised to see soy foods recommended so strongly in Dr. Li’s book and throughout this cookbook as well. There is so much misinformation and fear around this food, and it’s time to clear it up.

Soy foods are a staple in diets around the world, but especially in China, Singapore, Hong Kong, and Japan. This has allowed large, long-term, human studies on the health risks and benefits of consuming them.

Soy foods (and many other foods we eat) contain antioxidants called isoflavones, which are phytoestrogens , or plant estrogens. Though not exactly the same as human and animal estrogens, they are similar in structure and actually work as estrogen modulators. They have shown anticancer support in addition to health benefits for the heart and bones. The American Cancer Society and other major cancer organizations have statements about the safety of soy, so it really is time to change our tune about this incredibly healthy food.

Cells in all tissue and organs are constantly being maintained and repaired, and the body must be able to regenerate cells as needed in order to survive. Whereas angiogenesis is the process of growing new blood vessels to support healthy tissue, stem cells are the way that the intestines, lungs, skin, blood cells, and even your bones are renewed throughout your life. Cells in the colon regenerate every four days, which is relatively quick. Some white blood cells live for about a year (others have a much shorter lifespan), whereas red blood cells survive for about three months, and platelets only last for about 12 days. The body’s natural ability to regenerate cells is a key to survival, and certain foods contain compounds that can help support the process.

Stem cells are the engine that powers regeneration in the body. Stem cells in adults are not specialized but remain ready to regenerate when needed due to injury or illness in organs and tissue in the body. Many stem cells are stored in the bone marrow and are activated by an enzyme called vascular endothelial growth factor (VEGF). Stem cells are guided to the place they’re needed through cell-to-cell communication. Once they arrive at their destination, they transform into the heart, skin, or other organ tissue they were called to regenerate.

One example of how amazing stem cells are is one that you may already be familiar with: a stem cell transplant for a person going through cancer treatment, which is a lifesaving therapy. It is done by transferring stem cells from a donor to a patient with cancer in the hope that the donor’s stem cells will help the patient’s body make healthy new blood cells. Cure rates of some blood cancers are now around 90%, thanks to stem cell therapy.

Stem cells also support your heart and vascular system. If there’s a blockage or the blood flow through arteries or into the heart is compromised, vascular stem cells help regenerate blood vessels to get critical nutrients and oxygen to the right tissues.

Stem cells can be damaged by chronic diseases, such as type 2 diabetes, or by lifestyle factors like smoking tobacco and excessive alcohol intake. This damage can lead to regeneration dysfunction, but the good news is that there are many foods you can eat that support healthy stem cells.

Cocoa powder, which is rich in antioxidants, supports healthy stem cell recruitment. Anti-inflammatory omega-3 fatty acids, found in some fish as well as plant foods like flaxseed, chia, hempseed, and walnuts, have been shown in studies to help stem cells function better by migrating around the body with more ease. In Eat to Beat Disease , Dr. Li analyzes research on how other foods, including whole wheat, green beans, rice bran, and turmeric, support stem cells and regeneration in the body. In addition, foods that are high in certain antioxidants like resveratrol (red wine!), zeaxanthin (corn, kale, mustard greens, and other leafy vegetables), and chlorogenic acid (coffee, black tea, and blueberries) have been shown in studies to help stem cells regenerate tissues in the body.

Several types of beverages can help stem cells circulate in the body more efficiently, and two of them contain alcohol: red wine and beer. This could possibly be because alcohol slightly thins the blood, and these beverages also contain a lot of unique antioxidants. If you abstain from alcohol, you still have options. Both green and black tea have been found to boost the number of stem cells circulating in the body (Fujiki et al. 2018; Mitra and Khandelwal 2017).

You’ve got a very large community of bacteria—in the trillions—residing in your intestines. This is called the gut microbiome. Research continues to explore how these bacteria support human health (Mohajeri et al. 2018). The interaction between the gut microbiome and health is complex. For example, the types of bacteria you have in your colon change through life stages, pregnancy, diet changes, and medications you take, especially antibiotics. Gut bacteria create metabolites (substances) that actually affect brain signaling and the immune system. By feeding the gut microbiome with healthy prebiotics and probiotics, you can keep this system working optimally, which is a key factor in protecting your health.

There are a lot of potential threats to the health of your gut microbiome, including certain diseases in the digestive tract, a diet that doesn’t properly feed the bacteria living there, and some medications. When gut bacteria become altered, serious diseases, including inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis, can develop. Alterations in gut bacteria can also affect the cardiovascular and immune systems.

Food allergies can also cause problems with the gut. For example, although high-fiber whole wheat would normally help the body’s natural defense systems, for those with celiac disease, it can damage health. When the immune system identifies gluten (the protein found in wheat) as a threat, a person with celiac disease will have an immune reaction in the gut that causes diarrhea or constipation (or both), weight loss, bloating, gas, and abdominal pain when they eat wheat.

Although there’s a lot still to be learned about the microbiome, like which bacteria are potentially beneficial and harmful, what ratios are optimal, and which individual strains may be ideal for human health, research does point to the fact that diversity in the bacteria seems to be positive. To foster diversity and keep the bacteria “happy,” it’s important to include foods that naturally contain microbes. This includes eating foods with probiotics, such as fermented foods, as well as foods with prebiotic fiber that support gut bacteria, like fruits, vegetables, whole grains, and beans.

Many culinary traditions around the world include foods that are prepared by bacterial fermentation, and there’s evidence that this process is beneficial to the gut, providing a dietary source of live microorganisms that may support the microbiome defense system. Kimchi, sauerkraut, and pao cai (Sichuan fermented pickle, usually made from cabbage) contain potentially beneficial microbes, in addition to being high-fiber foods (Marco et al. 2017). Cheese is also made using a starter culture that utilizes different bacterial strains. There’s some evidence that cheese, like Parmigiano-Reggiano, Gouda, and Camembert, can positively affect the bacterial biodiversity of those who consume it (Milani et al. 2019). Other fermented dairy products, like yogurt and kefir, have been shown to influence the gut microbiome within a month of consuming them daily (Volokh et al. 2019). Even sourdough bread, made with a bacterial starter (Lactobacillus ), which is ultimately cooked and does not contain live bacteria, could be helpful to human health by supporting the immune system (Zheng et al. 2015).

Your genetic blueprint is unique just to you. It is kept inside DNA in every cell in your body and is important to protect from damage. DNA is made of genes inherited from your parents that defend your body by telling it how to function optimally throughout your life. There are a lot of threats to your DNA health, including chemical and environmental exposure and even lack of sleep or exercise, that can lead to DNA damage and a weakening of this powerful defense system.

DNA damage can happen at high levels with normal exposures during daily life. For example, ultraviolet (UV) rays from the sun can do a lot of damage, increasing your risk of skin cancer. Smoking tobacco—either first- or second-hand exposure—is damaging to DNA because of compounds such as polycyclic aromatic hydrocarbons (PAHs) and nitrosamines, which can lead to increased risk of cancers of the mouth, throat, esophagus, stomach, colon, rectum, liver, pancreas, larynx, trachea, bronchus, kidney, bladder, cervix, and more.

PAHs and another toxic compound, heterocyclic amines (HCAs), are a common exposure that damages DNA when charred beef, pork, fish, and poultry are consumed. PAHs are also found in smoked foods.

Part of DNA protection has to do with the ends of chromosomes (the structures made of DNA found in the nucleus of every cell), telomeres, which are the protective caps on the ends of DNA strands. There is important research on what can harm telomeres, damaging DNA and leading to an increased risk of certain cancers, and what can protect them. A lot of that has to do with diet. Studies on soda consumption in children have shown that it shortens telomeres (Wojcicki et al. 2018), whereas studies on the intake of antioxidant-rich foods and omega-3 fatty acids have shown that they offer protection (Prasad, Wu, and Bondy 2017).

The most important foods that help protect against DNA damage fall into three categories: those high in antioxidants that help protect DNA, those with epigenetic effects that may help repair broken DNA or influence DNA function, and those that help protect telomeres.

Research has identified that juices from fruits like grapes, pomegranates, cherries, and blackberries can protect against DNA damage, as can kiwi, carrots, broccoli, and foods rich in the compound lycopene (tomatoes, watermelons, guava, pink grapefruit).

Foods rich in omega-3 fatty acids, including salmon, hake, sea cucumber, manila clams, tuna, yellowtail, walnuts, chia, hemp, and flaxseed, have anti-inflammatory effects and help improve DNA repair in cells.

Still other foods contain compounds that actually influence how DNA functions by activating and deactivating it as needed. Foods with this unique ability include soy, cruciferous vegetables (broccoli, cauliflower, Brussels sprouts, kale, cabbage, etc.), coffee, green tea, turmeric, and herbs like basil, marjoram, sage, thyme, and peppermint.

One of the body’s most important defenses is a robust immune system, which plays a protective role in fighting off disease. Because of the complex nature of how this system works, there are many factors that could negatively affect it. Immunodeficiency diseases (there are more than 300) are caused by defects in the immune system and can cause recurrent infections. Though rare, they still affect 1 in 100,000 people, not including those diagnosed with Human Immunodeficiency Virus (HIV) or those who take immune-suppressing medications. The immune system can also work against itself in a condition referred to as autoimmune disease, which is discussed in the next section.

Many lifestyle factors that affect the immune system are within your control. Regular exercise, quality sleep, and certain foods can support and optimize immune defense. Chronic stress, lack of sleep, and malnutrition lower the body’s ability to fight infection and disease. Alcohol, especially chronic alcohol abuse, can suppress the immune system. In addition, being either underweight or obese can lower the immune response in both children and adults.

Although the immune system works hard to protect the body from invaders, it can also work against you if it becomes overactive and begins attacking itself, creating chronic inflammation. This is what happens in autoimmune disease, which includes more than 80 chronic illnesses and affects more than 24 million Americans. Among the most well-known autoimmune diseases are type 1 diabetes, rheumatoid arthritis, multiple sclerosis, lupus, Sjögren syndrome, and Hashimoto’s thyroiditis.

Nutrition plays an important role in autoimmune disease because certain foods can calm inflammation, reduce symptom flares, and help the body heal. Whole, minimally processed foods that are rich in antioxidants can be especially beneficial.

Many macronutrients and micronutrients work together to support a strong immune system. The food you eat can absolutely make the difference. Vitamins A, C, D, and E as well as B vitamins, like folate and B12 , are critical parts of immune cells. Iron, selenium, and zinc each play unique roles in the immune system, too. Protein is an important foundation for enzymes and cells that are required to help the body fight infection and disease.

Whether a nutrient is needed for creating B cells (which mark invaders to create antibodies), T cells (which respond by recognizing and killing bacteria, viruses, and cancer cells), or the many enzymes that orchestrate this entire complex system, eating a variety of foods is important.

Certain foods have shown promise in creating a healthy immune response, whereas others can calm the chronic inflammation caused by autoimmune diseases. Studies have shown that some nutrients, namely vitamins, minerals, and antioxidants, including carotenoids and polyphenols, can support immunity (Lange and Nakamura 2020). The nutrients that have also been shown to decrease inflammatory markers are found in many foods. For example, carrots, sweet potatoes, and tomatoes are high in carotenoids, and berries, cocoa, and beans are high in polyphenols. As an added bonus, many of these foods also contain fiber to help support a healthy gut microbiome.

Now that you have a foundational understanding of the science behind the body’s five major defense systems that Dr. Li establishes in Eat to Beat Disease , you can better understand the role food plays in optimizing how the body functions. You can also see the power that food has in fighting disease. Keeping the body in balance by providing the right types of nutrients is possible, and there’s a lot of research to prove it. Next up is a discussion of exactly how to put it into practice in your life.