In medical school and throughout his medical training, there was zero education about nutrition, says William Li, MD, a physician, scientist, and the president and medical director of the nonprofit organization the Angiogenesis Foundation in Boston. Dr. Li recalls patients in their fifties, sixties, and seventies who had failing health and chronic diseases like heart disease, diabetes, and cancer who were once athletes and soldiers at the peak of health when they were younger. Why were they ill now?
As Li began practicing medicine, “Virtually all of my patients asked me, ‘Doc, what should I be eating?’” So he set out to answer that by creating the “Eat to Beat” movement, which is based on food as medicine, he says. “I began to realize that diet and lifestyle was something that needed to be addressed by scientists and doctors, not just trainers and online gurus.”
That “Eat to Beat” movement has led to a book, Eat To Beat Disease: The New Science of How Your Body Can Heal Itself. That science is based on angiogenesis.
This may not be a term you’ve heard of, but when it comes to preventing cancer, or supporting your body’s defenses if you have the disease, it’s one you should pay attention to. “Angiogenesis is the process used by the body to grow blood vessels, which is crucial to our health. Blood vessels from our circulation, a 60,000-mile network that brings oxygen and nutrients to feed every cell in our body. Too few blood vessels and our organs starve and can die. Too many, and disease can result,” explains Li.
Li has been involved in the field of angiogenesis for more than three decades. As a result, “I have been involved with some breakthroughs in treating cancer, blindness, and diabetes — as well as food as medicine, since what we eat can help our angiogenesis system stay healthy,” says Li.
Ultimately, Li’s drive is a focus on prevention rather than solely treating disease. It’s food as a form of preventative medicine, he says. “Eating healthy food is something we can do for ourselves at home, under our own control, according to our own preferences, and between visits to the doctor’s office,” adds Li. And, he says, your diet can have a remarkable effect on cancer prevention and treatment.
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Diet and Cancer Prevention
What you eat makes a big difference in your body’s ability to prevent cancer. In fact, according to the American Cancer Society (ACS), at least 18 percent of all cancers and 16 percent of cancer deaths in the United States are related to lifestyle factors, including poor nutrition.
In a cancer-protective diet, the ACS specifically recommends colorful veggies like those that are dark green, red, and orange, and plant proteins like beans and peas, as well as fruit and whole grains. Lowering your risk of cancer is also about what you’re not eating. The ACS recommends keeping processed foods, red meats, alcohol, and sugary drinks (soda, sports drinks, fruit juice) to a minimum.
That falls in line with the Cancer Prevention Recommendations from the World Cancer Research Fund, which is part of the American Institute for Cancer Research. The organization suggests filling most meals with plant foods including whole grains, legumes, nonstarchy veggies, and fruit. A plant-based diet is one that’s rich in fiber (which helps protect against colorectal cancer), vitamins, and minerals. This also naturally pushes out less-healthy fare, like those foods that contain refined flour and sugar, which tend to be higher calorie and thus promote a higher body weight. There are 13 cancers that are associated with being overweight or obese, including cancer of the esophagus, gallbladder, liver, and pancreas, points out the Centers for Disease Control and Prevention (CDC).
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Li has a popular TED talk: “Can We Eat to Starve Cancer?” which has more than 1.7 million views. The talk introduces the audience to using anti-angiogenic therapy as a cancer therapy. This means eating foods that contain anti-angiogenic substances (more on this in a minute), which reduce angiogenesis, stopping tumors from developing blood vessels and growing.
While you shouldn’t replace medication with diet, some foods, Li says, have potent anti-cancer properties. Those include tea, turmeric, citrus, grapes, garlic, berries, and tomatoes. Tomatoes specifically contain the powerful antioxidant lycopene. Turmeric contains curcumin, a polyphenol (plant compound) that may possess anti-cancer activity, points out a review published in October 2019 in Nutrients. Yet this compound, like many others, has shown conflicting and limited evidence in cancer treatment, which suggests there is not just one “it” food, but an entire pattern of eating rich in a rainbow of foods that supplies a variety of these anti-angiogenic substances that’s critical.
Dietary patterns have been shown to affect certain types of cancer. In a study published in June 2015 in Cancer Prevention Research on over 900 men with prostate cancer, those who followed a “prudent” dietary pattern (that is, one that is linked to disease protection, and features veggies, fruits, fish, legumes, and whole grains) were 36 percent less likely to die from any cause compared with men who followed more of a processed foods Western-style diet.
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Popular Diets and Cancer: What’s the Deal?
It’s probably no surprise by now, but popular plant-based diets are often recommended for the prevention of cancer:
The Mediterranean Diet A review published in the journal Nutrients in September 2019 concluded that the Mediterranean diet was helpful in preventing cancer occurrence, particularly, as researchers note, there’s a high intake of olive oil and fresh fruits and vegetables. These foods help reduce inflammation and contain antioxidants to prevent DNA damage that may eventually lead to cancer.
Dietary Approaches to Stop Hypertension (DASH) This diet focuses on vegetables, fruits, low-fat dairy, whole grains, fish, poultry, and nuts, while encouraging sodium reduction, notes Mayo Clinic. A systematic review and meta-analysis of 17 studies, published in the Journal of the American College of Nutrition in May 2018, suggests that following the DASH diet is associated with a 16 percent lower risk in death from any cancer, and was particularly linked to a reduced likelihood of developing colorectal cancers compared with those whose diets don’t adhere to the guidelines.
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Q&A With Dr. Li: What Does He Eat to Help Prevent Cancer?
Here’s a look at how Li personally approaches food personally to help keep cancer at bay. Responses have been edited for concision and clarity.
EH: What does a typical day of eating look like for you?
WL: I will start breakfast with green tea or black coffee, with a little fruit.
Lunch tends to be on the light side, something tasty with some veggies and protein. For example: A ripe peach, a small piece of salmon, and a little quinoa, sprinkled with oregano, and a dash of olive oil. Honestly, sometimes I get so busy, I skip lunch. But that’s okay because it reduces the calories I take in over the course of a week.
Dinner I save for something I really enjoy. I always build my meal around seasonal foods, especially vegetables (kale, spinach, broccoli, red peppers, carrots) and fruits. I do enjoy seafood and sometimes a little chicken thigh, but they are not on my plate every day. If I snack, I love to eat tree nuts, like pecans or walnuts. I will sip tea in the evening, which I find calming.
EH: Why is this the diet you follow?
WL: I follow several principles. One: Focus on plant-based foods, and build everything around at least one vegetable or fruit at every meal. Two: Eat whole foods seasonally, whenever I can get them. Three: I have to love what I eat, or I would rather pass. Four: Eating less calorically may help people live longer, so I quit the clean plate club many years ago. Five: I eat diversely, which means lots of variety from meal to meal. Taken together, these rules combined with the list of more than 200 healthy foods I can choose from that are in my book, make eating to be healthy an enjoyable experience.
EH: What’s your favorite healthy snack and why?
WL: My favorite snack is a handful of pecans. They are tasty and packed with fiber and healthy fat. In a study in the Journal of Clinical Oncology in April 2018, patients with stage 3 colon cancer who ate two or more servings of nuts per week were more likely to survive and less likely to experience a cancer recurrence compared with nut-free folks.
EH: How about your go-to quick breakfast? Why?
WL: Whatever fruit is in season and ripe. Stone fruits, like peaches, plums, and mangoes, have antiangiogenic compounds that have been shown to decrease risk for certain cancers. Apples, specifically Granny Smith and Red Delicious, and berries are other antiangiogenic fruits.
EH: When you’re feeling rundown, which foods or drinks do you rely on to boost your energy? Why?
WL: I naturally have a lot of energy, but admit I drink a lot of tea and coffee. The good news about these is that they contain disease-fighting flavanols as well as caffeine. I find staying hydrated is critical to keep up my energy level, but so is getting a good night’s sleep and having regular exercise.
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EH: Is there a cooking method or technique that you gravitate toward? Or one you avoid? Why?
WL: I love to stir-fry, which is quick and seals in flavors and nutrients, making food tasty and healthy. I avoid deep frying. Past research has connected consumption of deep-fried foods to prostate cancer; cooking at high temps, like frying, also forms acrylamides, which have been rated by several agencies, including the International Agency for Research on Cancer, as a probable human carcinogen.
EH: How do you treat yourself?
WL: Just taking a break from the various tugs and pulls of life. Taking a walk by myself in the outdoors — clearing my mind is a treat I relish.
EH: What’s one healthy habit you wish you practiced more of? Why?
WL: Meditation. I’m always on-the-go and push myself to do more, so my life is super-fast-paced. When I have a chance to take a pause and meditate, I feel peaceful and can recharge. I would like to do more of that.
EH: Are there any foods you would never eat? Why?
WL: I never eat old-school junk food, like ultraprocessed chips and other snacks. A study published in the BMJ in February 2018 concluded that increasing the amount of ultraprocessed foods you eat by 10 percent also increased the risk of cancer by 10 percent.
What’s more, ultraprocessed foods are made with artificial flavoring, colors, and preservatives. We now know that many of the artificial chemicals found in snacks like chips, candies, and other popular snack foods actually cause harm to our gut microbiome, the healthy bacteria in our intestines that helps control our metabolism, our mood, and our immune system. We need to treat our gut properly and avoid those types of foods.
EH: What’s your strategy when eating out?
Li: Before the pandemic, I enjoyed dining out often. My approach to ordering from a menu is to scan the choices for vegetables, legumes, herbs, spices, and other ingredients that I recognize and know activate my health defenses. Then, I decide if the proteins they are paired with, like seafood, are something I want to eat at that moment. My food always has to taste good. These days, I rarely go out to eat, but I will still order carry-away using the same philosophy.
EH: Wine with dinner: Yes or no? Why?
WL: I do enjoy red wine and will occasionally have a glass or two with a nice dinner. Very modest wine drinking is fine for your heart and even for reducing risk of some cancers — and some existing research supports it — with a couple of caveats. First, the benefits come from the polyphenols found in the red wine, not from the alcohol itself. And second, a glass or two with a meal is about as much as you would want. For me, I save my red wine for a fine meal—usually cooked by myself using delicious whole plant-based foods.
EH: What’s one small change you’ve made — dietary or otherwise — to help reduce the risk of cancer?
WL: I cut out all processed meats from my diet, which are classed by the World Health Organization as a carcinogen.
EH: What’s one small change anyone can make to help better manage cancer?
WL: If someone has cancer, they need to cut out ultraprocessed foods and eliminate all added sugar to their diet. To know what an ultraprocessed food is, is to follow this simple rule: If it comes in a box or a can, and the ingredient label is long and filled with chemical names you can’t easily pronounce, and don’t recognize as healthy — it’s a good bet that it is ultraprocessed.
EH: Any final thoughts on the link between eating choices and cancer?
WL: If you want to eat to beat cancer, there’s a wealth of epidemiological research showing what we eat can be associated with cancer risk. Reducing or eliminating foods that damage your health defenses, like ultraprocessed foods, is a good move. And eating more whole plant-based foods because they are rich in natural cancer-fighting bioactive substances is wise and can taste great. Drinking green tea is also a simple way to lower cancer risk.
William W. Li, MD, is an internationally renowned physician and scientist, as well as the author of the New York Times bestseller Eat to Beat Disease: The New Science of How Your Body Can Heal Itself. His groundbreaking work has led to the development of more than 30 new medical treatments and impacts care for 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 1.7 million views. Dr. Li has appeared on Good Morning America, CNN, CNBC, and the Dr. Oz Show, and he has been featured in USA Today, Time Magazine, The Atlantic, and O Magazine. He is president and medical director of the Angiogenesis Foundation and is leading research into COVID-19.