“Let food be thy medicine, and let medicine be thy food.” This famous quote is often attributed to Hippocrates, who was the Greek founder of western medicine. This quote holds so much value since nutrition plays a huge role in our health outcome. From strengthening our microbiome to helping our body regenerate healthy cells, food is a powerful form of medicine that is often overlooked. 

 We spoke about this topic with Dr. William W. Li, an internationally renowned physician, scientist, and author of the New York Times bestseller Eat to Beat Disease: The New Science of How Your Body Can Heal Itself. His 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. 

Here, Li shared what we should be eating every day to stay healthy and fight off chronic disease. He also provided tips on eating well on-the-go and the top wellness hacks he swears by.

What are your top five non-negotiables in regards to what you should not do when it comes to health and nutrition?

Don’t get addicted to drinking soda – the added sugar of regular soda consumption is destructive to your metabolism.

Don’t use artificial sweeteners – studies have shown many artificial sweeteners alter your healthy gut microbiome, which can alter metabolism and damage your health defenses.

Don’t use plastic containers to store your food – containers can shed microplastics into food which has unclear health implications.

Don’t put milk in your tea – adding dairy can reduce the bioavailability of the beneficial catechins found in tea.

Don’t eat factory-processed preserved meats – epidemiological data shows that regular consumption of processed meat is associated with an increase in colon cancer.

Your book Eat to Beat Disease is based on the science of how our bodies can heal themselves. What are your top foods that activate our health defenses? 

1) Green tea

2) Brassica vegetables

3) Tree nuts

4) Extra virgin olive oil

5) Berries of all types

Finding ways to kill cancer stem cells has been one of the holy grails of cancer research. What are your thoughts on this and are there any foods that have the ability to target and suppress cancer stem cells? 

Walnuts, extra virgin olive oil, dark chocolate, and green tea have all been discovered to stop the growth of cancer stem cells. Drugs have not been able to do the same without causing toxicity. One of the advantages of researching food as medicine, especially for cancer, is the ability to add to the armamentarium to help patients without increasing side effects. More research is needed, but the cancer stem cell-fighting activity of certain foods is an exciting and important new path for cancer research.

What are the top foods to protect our skin?

Fruit peel contains ursolic acid, which helps to stimulate blood vessel growth for better circulation. 

When it comes to protecting against photoaging from the sun, watermelon and tomatoes contain the bioactive lycopene that reduces DNA damage caused by ultraviolet radiation (sun damage) to the skin.

To help with inflammation, broccoli, citrus, and kiwifruit are good sources of vitamin C which has potent anti-inflammatory benefits in the body. They are also whole foods that contain fiber, which feeds the microbiome, and well-fed gut bacteria produces their own anti-inflammatory substances called short-chain fatty acids (SCFAs).

Since inflammation is a culprit of disease and aging, which foods make the biggest impact on inflammation in our bodies?

Foods that ignite inflammation should be avoided or consumed in moderation, including candy and cakes, and grilled meats.

Foods that suppress inflammation are helpful to increase your diet, like turmeric, broccoli, and other brassicas (kale, cauliflower), green tea, coffee, and seafood rich in omega-3 fatty acids. Also, vitamin C-containing foods such as strawberries, red bell pepper, and citrus provide anti-inflammatory benefits.

Foods with high dietary fiber, such as nuts, brassica, and fruits like pears and kiwi, feed the gut microbiome, as do fermented foods like yogurt, sauerkraut, and kimchi, which all lower inflammation.

Do you believe supplements have a place in disease management? If so, which ones do you recommend alongside a healthy diet? 

The world of supplements is huge and full of exaggerated claims, but the science says that daily multivitamins can be beneficial for those who are not regularly eating a healthy diet. Vitamin D, in particular, has cancer-preventative and immune-supporting benefits. Omega-3 supplements are beneficial for your overall body’s health defenses and aid your metabolism. While the jury is still out on which are the best probiotics to take, many people report their gut feels better when taking a probiotic.

It’s been said that health starts in the gut. What are some uncommon foods we should incorporate into our diet to help support a healthy microbiome? 

Omega-3 fatty acids are healthy for the gut microbiome. Some unusual foods that contain them are seaweed, like wakame, kombu, and dulse. These can be found in various dried forms and ordered online. If you enjoy seafood, there are many different types of fish and shellfish that are rich in omega-3 fatty acids as well.

Dark chocolate, made with 80% of higher cacao, contributes dietary fiber that is good for the gut microbiome.

What role does vitamin C have on autoimmune diseases? 

Vitamin C has been shown to reduce the flare of autoimmune diseases like lupus. 

What are some of the best herbs and spices to help fight disease?

Herbs and spices mostly enhance the flavor of foods and make your meal tastier and more delicious. That said, many of them contain useful bioactives like rosmarinic acid and other polyphenols that activate your health defenses. Examples include rosemary, thyme, oregano, and basil. Turmeric, ginger, and fresh cracked black pepper, as well as dried chili, also have potent bioactives that boost health.

When traveling, what are some of your top tips for eating healthy while on the go?

Look for the healthiest choices possible that you enjoy.

Don’t worry if you wind up skipping a meal or two if you can’t find something that fits the bill. This lowers your calorie intake and effectively is a type of intermittent fasting, which benefits your metabolism and health defenses.  

Make sure you plan for one healthy delicious meal each day. Take the time to research where you might go to have this meal or prepare it yourself.

Avoid snacking. Most of the packaged snacks you buy on the road are packed with artificial preservatives, coloring, and flavoring.

Can you share some of the newest research you’ve discovered regarding food?

Chili peppers contain a bioactive called capsaicin that activates a receptor on your tongue, giving the sensation of “burn.” This signals your brain to release hormones that are sent down from your head to your chest and belly. The hormones trigger a set of reactions in a special kind of fat called brown fat. When brown fat is activated, it becomes a space heater in your body and burns down energy derived from a type of fat called white fat. So you can eat spicy foods to help your “good fat” burn down “bad fat.” I write all about this in my new book Eat to Beat Your Diet because these new concepts of metabolism show that we can control our own metabolic destiny by controlling body fat.

Can you share your daily wellness routine?

First, I try to make sure I get good quality sleep. Sleep restores your body’s health defenses, including your immune system. Eight hours of sleep is the ideal number, but in reality, I probably get less. Everyone’s needs and situations are different. The key is to be mindful of your sleep pattern. 

Second, I stay active. Even if I’m busy or traveling and can’t work out, I try to walk briskly for at least 30 minutes every day. Staying active is good for your body as well as your brain. I drink coffee or tea every day. They contain bioactives that boost all five of your body’s health defenses — angiogenesis, regeneration, microbiome, DNA protection, and immunity — as well as improve your metabolism and fight harmful body fat. 

Finally, I choose the food I eat carefully. It must be tasty and healthy at the same time. If I can’t find that combination, I’m happy to skip a meal — a little fasting is good for your health.