by STACEY COLINO
illustrations GRACIA LAM
Your gut health has a major influence on your immunity and protecting your overall health. In part, that’s because the immune system cells in the digestive system make up 70 percent of the body’s entire immune system, says Emeran Mayer, MD, distinguished research professor in the Department of Medicine at UCLA.
The community of microbes that live in the gastrointestinal tract is called the microbiome, and there’s an intricate communication between those microbes and the gut-associated immune cells. This keeps the immune system active, as the good bacteria produce anti-inflammatory substances.
A combo of lifestyle factors keeps your immunity strong, but experts say that if they had to pick a top one, it would be diet. “Diet is foundational because the nutrients in food provide the building blocks for the immune system,” explains David L. Katz, MD, MPH, past president of the American College of Lifestyle Medicine.
We map out which foods give the strongest benefits.
The more plant-based foods you work into your diet, the heartier your gut and immune system will be, says Justin Sonnenburg, PhD, professor of microbiology and immunology at Stanford University and author of The Good Gut.
Nutrient-rich foods that support your gut—including naturally fermented foods, prebiotics, fiber, and polyphenols—decrease inflammation and help with the production and activation of immune cells, which fight off infection. Case in point: A recent study found that people who ate a plant-based diet had a lower risk of contracting COVID-19, and if they did get it, their illness wasn’t as severe compared with people who had a lower intake of fruits, vegetables, and other plant-based foods. “There is scientific evidence that a healthy gut microbiome is protective against some viral infections that target the respiratory and pulmonary systems,” says Mayer, author of The Gut-Immune Connection.
The following vitamins, minerals, and nutrients do the most to fight inflammation and mobilize your immune cells.
● Vitamin A and beta-carotene are in carrots, dark leafy greens, red bell peppers, broccoli, and sweet potatoes.
● Vitamin C is plentiful in bell peppers, oranges, strawberries, broccoli, Brussels sprouts, tomatoes, and cauliflower.
● Vitamin D is found in trout, salmon, fortified milks, sardines, and eggs.
● Zinc is in fish, seafood, oats, pumpkin seeds (pepitas), lentils, and Greek yogurt.
● Antioxidants such as polyphenols (in apples, berries, broccoli, citrus fruits, plums, tea, and coffee) protect the gut lining and help support healthy bacteria growth.
● Probiotics are beneficial bacteria and other microorganisms that help keep your microbiome healthy. Probiotic fermented foods like yogurt, kefir, kimchi, kombucha, miso, sauerkraut, and tempeh. “Fermented foods directly deliver probiotics,” says Katz, coauthor of How to Eat. “You’re replenishing live cultures in the microbiome.”
● Prebiotics are nondigestible forms of fiber that act as food for your gut microbiome. Natural sources of prebiotics include apples, asparagus, bananas, barley, garlic, artichokes, oats, onions, peas, soybeans, green leafy vegetables like kale, and wheat.
● Protein is important for immune cell growth, activation, and regeneration. Black beans, lentils, nuts, and quinoa are good plant-based sources. You’ll also find protein in yogurt, kefir, and milk.
Fortunately, many of these foods have multiple immune-friendly nutrients. For example, Greek yogurt is rich in both probiotics and protein. Onions are loaded with antioxidants and prebiotics that nourish gut bacteria. Apples have vitamin C and fiber—the skin has insoluble fiber, and the pulp is rich in soluble fiber and pectin, which is a prebiotic, says Gail Cresci, PhD, RD, a microbiome researcher and nutritionist with Cleveland Clinic. “Oats also have soluble fiber and beta-glucan, which is a prebiotic.”
Every year we hear the same question: Are there any supplements that truly help you dodge colds and other viruses? The answer: The evidence regarding most supplements is mixed, but there’s solid research showing that taking zinc supplements or lozenges can help prevent symptoms of upper respiratory infections. What’s more, if you take zinc daily when you start feeling respiratory symptoms (coughing, sneezing, runny nose), you can shorten their duration by an average of two days. “Zinc is directly related to certain immune cells that respond to viral infections,” Katz says. More incentive: Most of us probably don’t get enough zinc in our daily diets.
Some of these healthy eats may feel unfamiliar, but many are variations on foods you’re likely already eating. The wider variety of gut-healthy foods you eat, the more nutrients you get, so here’s how to expand your base.
● If you’re already eating yogurt, try kefir, which is loaded with probiotics. Research has found that consuming kefir helps your immune system respond to viruses so they don’t take hold in your body.
● If you’re a fan of oatmeal, you might also like barley cereal, hot or cold. Barley is full of fiber and prebiotics that nourish your gut bacteria. Top with pumpkin seeds for a dose of zinc.
● If you’re a tea drinker, try kombucha, a fermented tea that contains immune-boosting antioxidants as well as bacteria and yeast that are good for gut health.
● If spinach salad is your go-to lunch or side dish, consider adding dandelion greens. You’ll get an extra dose of vitamins A and C and prebiotics.
● Already eating veggie burgers? Black bean burgers are a good option. Black beans are good sources of protein, fiber, and zinc plus other nutrients.
● If you usually put relish on your burger, try sauerkraut. (You want the type that’s stocked in the refrigerated section of the grocery store, not the kind in a can or jar on a shelf.)
● If you love the comfort of chicken soup, try miso soup with mushrooms. Miso is made from fermented soybeans (which means it contains probiotics), and mushrooms contain the prebiotic beta-glucan.
● If you often make omelets with spinach and cheese, you can add chopped tempeh, mushrooms, and dandelion greens for a triple whammy of vitamin D and prebiotics.
ILLUSTRATOR AGENCY: THE LOUD CLOUD