In the current COVID-19 era, all eyes are on what we can do to stay healthy. And while the Centers for Disease Control and Prevention (CDC) has recommended many measures to that end — including wearing masks, washing hands, and physically distancing — there’s another, often overlooked way to better your immune system: focusing on your diet.
“Nutrition and how it impacts your immune system is all the rage these days because of COVID-19,” says Megan Meyer, PhD, the Durham, North Carolina–based director of science communication at the International Food Information Council (IFIC). Dr. Meyer earned her PhD in microbiology and immunology with a focus on nutritional immunology from the University of North Carolina in Chapel Hill in 2015. She now lives with her husband and 1-year-old daughter, and spends her workdays translating scientific nutrition language into information that the rest of us can understand.
Meyer has always been into food — she grew up in a family that loves to cook. “My grandparents immigrated from the Philippines in the ’50s, and a lot of our family recipes are Filipino food,” she says. As an undergraduate studying biology, she became interested in the interplay between what we eat and how it impacts our immune system.
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Turns out, the link is strong, but when it comes to bolstering immunity with food, there’s no magic bullet.
Diet and Disease Prevention
The foods that fuel your body can make a difference in how your immune system performs. According to an article published in August 2019 in Nutrients, proper nutrition is necessary for all cells to function as they should — including immune cells. By eating well, the body is equipped to fight back against pathogens and avoid dangerous inflammation.
Inflammation normally helps the body fight infections and can become a problem if it’s chronic, which means the immune system stays turned on, according to Harvard Health Publishing. Chronic inflammation is associated with many dangerous health conditions, including heart disease, cancer, diabetes, arthritis, and bowel diseases.
Foods that help fight inflammation include berries, red grapes, onions, and green leafy vegetables. On the other hand, foods that may contribute to inflammation include white bread and pasta, processed meat, and foods with added sugar, according to Harvard Health Publishing.
A balanced, nutrient-rich diet high in anti-inflammatory foods can help you steer clear of dangerous health conditions. According to the CDC, sticking to a healthy diet encourages proper growth and lowers your risk of chronic health conditions, such as obesity, heart disease, type 2 diabetes, and some cancers.
As for the role of nutrition in preventing COVID-19, an article published May 2020 in the Pakistan Journal of Medical Sciences noted that following a heathy diet puts the body in the best position to ward off illness, though there hasn’t been research yet linking specific nutrients to reducing the risk of contracting the virus.
A poor diet can have the opposite effect, however. Eating saturated fats, sugars, and refined carbohydrates can promote inflammation and impair immunity, which could increase the risk of having a severe case of COVID-19 if you get it, according to a July 2020 article published in Brain, Behavior, and Immunity.
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Diet and Disease Treatment
As with preventing disease, the food you eat can influence the immune system, increasing the body’s response to inflammation and reducing the risk of infection, according to a review published January 2017 in Journal of Traditional and Complementary Medicine.
The antioxidant and anti-inflammatory properties present in some foods contribute to the fact that proper nutrition may play a role in treating health conditions and helping certain groups of people, too. Antioxidants are substances that can prevent or slow down cellular damage, according to the National Center for Complementary and Integrative Health.
The antioxidant vitamin C, for instance, can help you recover from a cold more quickly, according to a previous review.
And zinc, another antioxidant, helped people who had a cold recover three 3 faster than those who didn’t take zinc, according to a study published in April 2017 in Open Forum Infectious Disease.
A review published March 2018 in Journal of Translational Medicine noted that what you eat and the supplements you take, such as omega-3 and polyphenols compounds, may enhance the immune system’s battle against cancer and potentially lower the risk of premature death.
And the aforementioned Journal of Traditional and Complementary Medicine review concluded that foods have the power to influence immunity, prevent disease, and treat health conditions, such as in neck and esophageal cancer patients who were being treated with radiochemotherapy.
For example, foods high in omega-3 fatty acids and the amino acid arginine (found in fish, meat, and whole grains) enhanced the immune response in surgical cancer patients, reducing the risk of complications and premature death, according to a previous study.
The association is so strong that the U.S. Department of Agriculture (USDA) offers information for how healthy eating can keep various health issues under control, such as cancer, diabetes, and osteoporosis.
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Popular Diets and the Immune System: What Might They Do to Help?
How should someone eat if they’re trying to boost their immune system? “As boring as it sounds, it’s just a healthy diet,” Meyer says.
Unfortunately, there’s no one food to eat or to avoid in order to reap the benefits. Same goes with macronutrients (protein, fat, and carbohydrates) and micronutrients, such as vitamins and minerals. “It would be hard to say that one macronutrient or micronutrient is a thing you want to double down on,” Meyer says. “There’s so much interplay happening.”
Instead, an all-around healthy diet filled with all three macronutrients and plenty of micronutrients delivers the best results, she says. All of these components play a role in building a healthy immune system.
“Making sure you’re getting those big macronutrients from a variety of sources is really important,” Meyer adds. Certain vitamins and minerals have also been shown to have a particularly positive effect. Meyer points out that vitamin D (found in fish and eggs), and more present in sunlight and supplements, along with zinc (found in shellfish, poultry, and beans) are two well-studied nutrients that support the immune system.
The University of Cincinnati Medical Center adds these to the list:
- Vitamin C, found in citrus fruits
- Beta-carotene, found in greens and root veggies, including sweet potatoes and carrots
- Vitamin E, found in nuts, seeds, and greens
- Antioxidants, found in plant-based foods and drinks such as green tea
- Probiotics, which are beneficial bacteria that help maintain a healthy balance in the body, found in yogurt and kimchi, per the Cleveland Clinic
- Vitamin B6, found in poultry, fish, chickpeas, bananas, and some breakfast cereals
As you can see, there’s a wide range of healthy foods that make up an immune-boosting diet. “A few diets are built around these fundamentals, such as the Mediterranean diet and the DASH diet, because they incorporate lean protein, unsaturated fat, fiber, whole grains, fruits, and veggies — the basics,” Meyer says.
And, alternatively, a traditional Western diet, which is generally high in added sugar and saturated fats, and low in healthy complex carbohydrates, fiber, micronutrients, omega-3 fatty acids, and other bioactive molecules such as polyphenols, has been shown to promote inflammation, which can contribute to health conditions including obesity, cardiovascular disease, and insulin resistance, according to the article published August 2019 in Nutrients.
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Q&A With Meyer on What Her Immune System–Friendly Diet Looks Like
Knowing everything she does about nutrition and the immune system, we asked Meyer to give us the scoop on what she eats on a regular basis. Responses have been edited for concision and clarity.
Everyday Health: What does a typical day of eating look like for you?
Meghan Meyer: During the week, I’m very routine because I’m looking for something that will fill me up and also taste good. I typically will eat yogurt and granola or oatmeal in the morning because those are things that are easy to prepare in batch or quickly put together.
Lunch is usually leftovers or two runny eggs with greens and bread or an everything bagel.
For dinner, I introduce more variety. We like to cook a lot in our house, and we’ve gotten really into Sichuan cooking lately. That type of cooking prioritizes vegetables and a small piece of meat or no meat sometimes, just tofu, plus rice of course. We most recently had mapo tofu (a popular spicy Chinese dish with tofu, ground meat, and fermented beans).
EH: Why is this the diet you follow?
MM: I’m always looking for that good combo of proteins, fats, and carbs. I’m not ravenous after an hour when I eat this way, so that’s really important. But in general, I try not to make my diet something I focus on. I just make healthy eating part of my routine. I’ve noticed that being surrounded by more healthy options, you gravitate toward those things.
EH: What’s your favorite healthy snack?
MM: I do a lot of snacking: whole-grain crackers and hummus, cheese and some veggies, or dark chocolate, nuts, and dried fruit. I put the snack in a little ramekin (a small bowl you might see used for soufflés) so mindless eating isn’t happening. I find that’s really helpful for me. I enjoy different textures and flavor combinations, and I think because my breakfasts and lunches are so standard, snacks are my way to branch out.
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EH: How about your go-to quick breakfast?
MM: I’ll make oatmeal for the week and be set. Typically in the summer, I will do overnight oats cold, and then in the colder months, I make a big thing of oatmeal that I heat up and put my toppings on every day. I make my oatmeal with milk and top it with nuts and some fruit or chia seeds for some more fiber and fats.
EH: When you’re feeling run down, which foods or drinks do you rely on to boost your energy?
MM: I definitely turn to coffee in the mornings. But when I’m feeling run down, I’m a big believer in sleep and getting outside and non-food-related things as much as possible. It’s really important to sleep eight hours at least at night, or try to go to bed early and get off screens.
EH: Is there a cooking method or technique that you gravitate toward?
MM: We roast a lot of vegetables, and we do a lot of wok cooking. I think it delivers a lot of char and flavor for veggies. Those are our current go-tos.
EH: How do you treat yourself?
MM: I’m a big believer in self-care. That could mean going on a walk with friends, or I try to exercise or move a couple times a week. That really keeps me sane — I’ll walk or run or do yoga. I take a lot of baths, especially in cold months. I read a lot and spend time with friends when we can.
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EH: Are there any foods you would never eat?
MM: I take a lot of pride in trying any foods, so there’s no food I’d avoid. I’ve heard of people eating a live octopus — that’s a little much for me. But I’d eat almost anything deemed as strange. There’s this blood dish in the Philippines called dinuguan, and I love it. I consider myself to have a pretty good relationship with food. I know that’s not the case for everyone and I don’t take that lightly. I think growing up around so much cooking and culture helped. Also, I have a curiosity around food and don’t associate fear or other negative emotions toward it, though I know some people struggle with that.
EH: What’s your strategy when eating out?
MM: Before COVID, when I would travel for work and I was eating out a lot, sometimes three times a day. I would try to have vegetables at least at lunch or dinner because that can be tricky when traveling. When I go out with a friend or my husband, we might split a meal or order a bunch of things so we can try lots of different dishes and then we’ll take the leftovers home for later.
EH: Wine with dinner: Yes or no?
MM: Sure — I’ll have a glass of wine three times a week and maybe a beer peppered in there as well. I’m a big fan of beer and used to brew beer before my daughter was born. Alcohol is probably the thing I keep more of an eye on, though. I don’t want to be drinking multiple drinks every night. I probably drink four or five times a week and keep it to a drink or two.
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EH: What’s one small change you’ve made — dietary or otherwise — to help your immune system?
MM: When I’m feeling sick, I’ll take a zinc supplement. That’s one thing I can think of where I changed my behavior. With zinc, catching it early on is what’s going to have the most effect. I would also say that I am still amazed by the effect of sleep and stress management has on the immune system. I’m all for cutting stress where I can, whether that’s having a frozen meal for dinner instead of cooking because it’s just easier and then pumping it up with frozen veggies. You can’t underscore the importance of the ease and convenience and also doing something for yourself. Eating a healthy meal, going to bed early, those are things I tried to implement in 2020 because it was an unprecedented year.
EH: What’s one small change anyone can make to help their immune system?
MM: That’s tough. There isn’t just one little thing and saying to eat a healthy diet isn’t necessarily a small change. But that’s it: A healthy, well-balanced, varied diet is definitely what’s going to set you up for a strong immune system.
EH: Any final thoughts on the link between eating choices and immunity?
MM: I never want it to seem like I think this is super easy. I want to acknowledge that as a society we’re struggling with eating healthy, and I don’t want to minimize any of the struggles that people are dealing with. Many people think, ‘Oh, I’ve got to cook every single meal, and I’ve got to kill it at every single eating event.’ But I think you can get pretty good nutrition from go-to easy meals. Use your pantry, use your freezer — those are things that will help you. I just try to do my duty and eat fruits and veggies. You don’t have to be perfect to make advances for your health.
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