The 5 Best Foods & Nutrients to Eat More of for a Healthy Immune System

The much-dreaded cold and flu season is upon us. With the added threat of COVID-19, it’s more important than ever to keep your body’s natural defenses strong. While no food or supplement can prevent or cure this coronavirus—or any cold or virus for that matter—along with basics like proper hand-washing (and getting vaccinated, of course), “a well-balanced diet allows your immune system to be the best version of itself,” says Kris Sollid, RD, senior director of nutrition communications at the International Food Information Council.

How can you bolster your defenses against the germs or viruses? Include these 5 immunity boosters in your diet, plus make sure to wash your hands, take a multi-vitamin and try to get enough sleep, too.

1. Leafy Greens

Leafy greens like bok choy, kale and spinach are rich in magnesium, which has been shown to play a role in how the body handles inflammation. In fact, an analysis of dietary data from more than 5,000 adults found that those who didn’t take in the recommended amount of magnesium were more likely to have elevated levels of C-reactive protein, a marker of chronic low-grade inflammation. That’s important because this type of chronic inflammation can make it harder for your immune system to do it’s job, says Taylor Wallace, Ph.D., an adjunct professor of nutrition at George Mason University in Fairfax, Virginia. Yet more than half of Americans don’t get enough magnesium in their diets. A half cup of cooked spinach gives you about 20% of the recommended Daily Value of 420 mg. Other good sources include legumes, nuts, seeds and whole grains.

2. Vitamin D

Having adequate blood levels of vitamin D could help ward off colds and flu. A meta-analysis of randomized controlled trials published in the journal BMJ found that participants deficient in this “sunshine vitamin” who took vitamin-D supplements daily or weekly had significantly fewer upper respiratory tract infections than those who didn’t. In many parts of the U.S., the sun doesn’t get high enough in the sky in winter for sufficient rays to reach your skin and spur your body to produce vitamin D. You may want to discuss your vitamin D levels and supplementation with your doctor. But you can also get this immune-supporting vitamin from foods like fatty fish, wild or UV-exposed mushrooms and vitamin-D fortified milk, orange juice and cereal.

3. Probiotics

Let this one marinate: a growing body of research suggests that your gut bacteria directly impact immune function. One study published in Cell Research suggests that the good bugs found in fermented foods like yogurt, kefir, kimchi, sauerkraut and tempeh can help fight viral diseases like the flu—and bolster your defenses against future infections. That’s because fermented foods offer double the gut benefits, says Wallace: they contain probiotics, enriching your gut with more beneficial bacteria, and they act as prebiotics that feed that bacteria and help it flourish.

4. The Mediterranean Diet

In a study out of Spain, families with children who suffered from frequent colds were asked to adopt a traditional Mediterranean diet—full of whole grains, fruits and vegetables and omega-3-rich foods like olive oil and seafood. After a year, the researchers saw a significant reduction in the number of times the children were sick, with just over 50% having no colds (compared to an average of around 5 episodes per child in the previous year). And treatment for cold symptoms fell by 57%. One reason why: a Mediterranean style of eating has been shown to be anti-inflammatory. Fish, in particular, is a good source of omega-3 fatty acids that help reduce inflammation and support immunity.

5. Chicken Soup

It turns out there is something to chicken soup after all. In one study, hot chicken soup was more effective than hot or cold water at making noses run—a good thing since nasal secretions help rid the body of pathogenic viruses and bacteria. Like any hot liquid, soup also helps you to stay hydrated and raises the temperature of the airways, both of which are important for loosening secretions. Adding a few hot chiles to this Chicken Noodle Soup with Dill recipe might help loosen things up even more.