Diet is a crucial piece of the immunity puzzle. “Eating the right foods helps your immune system function optimally and makes you more resistant to infection,” says Jennifer Johnson, ND, clinical professor at the University of Bridgeport in Connecticut. Here are the 10 powerhouse foods that will help you stay strong and sniffle-free during colds and flu season.
Readily available and generally acceptable to even the most finicky eaters (meaning, kids), the carrot is an immunity booster. Packed with beta-carotene (which the body converts into immune system–essential Vitamin A), just one raw carrot provides 175 percent of the Recommended Dietary Allowance (RDA) of Vitamin A. Diced small, carrots make an excellent base for soups, stews, and risotto. Sliced on the diagonal and roasted with olive oil, salt, and whatever fresh herb you have on hand, they also make a quick and naturally sweet side dish. If you don’t like them, try: red peppers, leafy greens, sweet potatoes, butternut squash, or cantaloupe—all of which are rich in beta-carotene.
2. Green Tea and Chamomile Tea
We’ve said it before, and we’ll say it again, keep drinking green tea. “Green tea is one of my top-10 favorites because it is a powerful antioxidant and has strong antiviral and antibacterial properties,” says Beth Reardon, director of integrative nutrition at Duke Integrative Medicine. She suggests drinking three to five cups of green tea a day to keep the immune system primed. “Antioxidants need to be replenished every few hours, and drinking green tea throughout your day fills that need.” If caffeine’s not your thing, chamomile tea has recently been shown to be a friend to immunity: Researchers at the Imperial College of London found that subjects who drank five cups of chamomile tea showed evidence of elevated levels of phenols—naturally occurring antioxidants that have been shown to have antibacterial powers. If you don’t like them, try: white tea (which has a milder flavor and a similar antioxidant profile to green tea).
3. Fermented Dairy
Yogurt, and its close relative kefir, is a great natural source of the health-promoting bacteria known as probiotics. These friendly little buggers are good for immunity for two reasons, Reardon says: They promote healthy digestion and thus help the body derive all the nutrients it needs from food to work efficiently. They also populate the lining of the gut, which means less space for aggressive bugs to take up residence. Some yogurts are better sources of probiotics than others; to be sure that yours provides a decent amount of actual living organisms, look for the “Live & Active Cultures” seal. This designator of the National Yogurt Association signifies that the yogurt contains at least 100 million cultures per gram of two specific strains of good bacteria. Kefir, a fermented dairy beverage that tastes like drinkable yogurt, typically contains more probiotic bacteria than yogurt, Reardon says. Whichever form you choose, she suggests getting one serving of a food high in probiotics per day. If you can’t tolerate dairy, Johnson advises trying goat milk yogurt, which leads to the next immunity food on our list. If you don’t like them, try: non-dairy fermented foods including miso, tempeh, and sauerkraut.
4. Goat’s Milk
You’ve likely tried goat cheese, but have you tried goat milk? This winter is the perfect time to give it a whirl: Two 2010 studies by Italian researchers found that goat’s milk stimulated an anti-inflammatory response in human immune cells and triggered the release of cells responsible for slaying invaders. If you don’t like them, try: dairy products made from goat milk, such as goat cheese or goat milk butter.
You’ve likely heard that certain types of mushrooms are immunity boosters, and for good reason. “The cell walls of mushrooms more closely resemble the cell walls of bacteria than other plants,” says Reardon. As a result, eating mushrooms is the equivalent of giving your immune system a dress rehearsal for colds and flu—when threatening bacteria show up, your immune cells will be primed to fight them off. And it’s not just the highly-acclaimed, exotic Asian varieties (shiitake, reishi, and cordyceps) that pack a health punch; a Tufts University study found that mice fed white button mushrooms had significantly increased levels of natural killer cells, a vital component of the immune system. Reardon cautions that it’s important to not eat white button mushrooms raw, as cooking de-activated some potentially harmful, pre-carcinogenic compounds that occur naturally in the mushrooms. If you don’t like them, try: mushroom supplements.
6. Brazil Nuts
These big beauties are one of the best food sources of the mineral selenium, which activate enzymes that are crucial to optimal immune function. Just two nuts supplies about 200 micrograms of the stuff—more than you need to keep immunity humming. If you don’t like them, try: Canned tuna or beef, two other good sources of selenium.
Love ‘em or hate ‘em, these briny bites are the best way to fill your zinc tank. And zinc is such an important piece of the immunity puzzle that studies have found it beneficial in treating diarrhea in children, hepatitis C, pneumonia, and respiratory tract infections (just to name a few). Reardon suggests making sure you get enough zinc by eating shellfish once or twice per week. If you don’t like them, try: lobster or Alaskan king crab, which are also packed with zinc.
8. Lima Beans
The key component that makes lima beans such a powerful immunity promoter is soluble fiber: Although all beans are good sources of soluble fiber, lima beans offer more than the rest—3.5 grams per serving compared to 1 gram for chick peas, lentils, and black-eyed peas. Soluble fiber turns gummy once you ingest it. This stickiness—think flypaper—helps it bind with things the body doesn’t need (such as germs) and sweeps them through the digestive tract and out of the body. A recent University of Illinois study found that mice fed a diet high in soluble fiber had markedly fewer instances of getting sick than mice that ate insoluble fiber. Lead researcher, Gregory Freund, explains that soluble fiber seems to work in two ways: it cools the inflammatory response, which helps the immune system function efficiently, and it’s a source of food for the beneficial bacteria in the gut that play an important role in keeping bad bacteria in check. You can purée them to make a delicious spread. If you don’t like them, try: fiber foods like phylum husks, Brussels sprouts, pears, citrus fruits, or kidney, black, navy, and pinto beans.
Here’s another one you probably already know about. Garlic’s status as a home remedy for treating colds and flu is second only to its reputation for being smelly. Western medicine theorizes it is garlic’s ability to increase levels of enzymes that help the liver detoxify the blood that gives it special immune powers. Reardon advises that garlic must be chopped or crushed and then exposed to air for several minutes to release its full enzyme power. Eating garlic raw provides maximum potency, but if you can’t stomach the strong taste, Reardon suggests adding it to hot foods at the very last stage of cooking. If you don’t like them, try: garlic supplements.
Winnie the Pooh knew that honey was worth going to great lengths to get, and not just for its sweetness. Honey has been long hailed by herbalists for its antibacterial properties. And recent research has found that honey can also ease a cough: A 2010 Iranian study found that children with upper respiratory infections saw a greater relief from a 2.5 ml serving of honey before bed than from over the counter cough suppressants. If you don’t like it (or are trying to avoid all forms of sugar), try: licorice tea, another traditional herbal remedy for coughs.
A healthy, balanced diet is always the best and most effective way in boosting your immune system. Immunity is important when fighting colds and flu. However, our diets can slip from time to time and we still want to be able to keep our immune system strong if that occurs. There are several different supplements that can be used to boost your immune system in addition to some foods you should stay away from, which can be found here.