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Your immune system can use all the help it can get. Even when it’s not cold and flu season, keeping your immunity in good shape is a smart idea.

In addition to practising well-studied healthy habits like getting adequate sleep, prioritising exercise, building relationships, engaging with your community, and using stress-relieving strategies, you can supercharge your immune system by noshing on nutrient-rich foods.

Seafood Provides Immune-Boosting Omega-3 Fatty Acids

The omega-3 fatty acids found in some types of fish such as salmon, sardines, herring, and mackerel, enhance the functioning of immune cells, says Erin Palinski-Wade, RD, CDCES, founder of the Vernon Center for Nutrition & Wellness in New Jersey and author of the 2-Day Diabetes Diet.

Palinski-Wade adds that DHA, a type of omega-3, may increase the activity of white blood cells, which further strengthens immunity. That’s backed up by a study that found this effect was not only significant but also happens quickly – within a week of consumption, the researchers said.

Healthy Proteins Bolster Disease-Fighting White Blood Cells

The National Institutes of Health (NIH) notes that zinc – a mineral abundant in oysters, poultry, seafood, beef, and lamb – works with protein to strengthen the immune system. Certain types of immune cells, including white blood cells, can’t function without zinc, according to a study review.

So whether you get your protein from lean meats, vegan or vegetarian foods such as tempeh or tofu, make sure you get some at every meal to keep your energy and your strength up, advises McKenzie Caldwell, MPH, RDN, of Charlotte, North Carolina. She notes that the recommended daily allowance (or minimum amount needed) for protein is 0.8 grams (g) per kilogram (kg) of body weight. (To convert to kg, divide weight in pounds by 2.2.) For example, a 150-pound person weighs about 68.2 kg, meaning they need about 54.5 g of protein each day.

For the most heart-healthy option, choose lean protein. According to the National Heart, Lung, and Blood Institute, lean protein has 55 calories and 2 to 3 g of fat per serving. Examples include 1 ounce (oz) of dark meat or chicken with the skin removed, 1 oz of roast beef, and low-fat cheese that has a maximum of 3 g of fat per oz.

Dark Chocolate Has Magnesium, Which May Strengthen Antibodies
and Help Prevent Disease

Plenty of vitamins and minerals play a role in immune function, but a particular standout is magnesium.

According to a 2022 study, your immune system is made up of numerous components, including proteins like antibodies, lymphocytes, and macrophages, which all work together to repel invaders such as viruses. Researcher Palinski-Wade notes that magnesium plays an important role by improving how each of these protein types function.

Previous research has noted for example, that magnesium helps lymphocytes bind to invaders so they can be removed from the body, and helps prevent antibodies from being impaired.

The Cleveland Clinic cites a breadth of foods with ample amounts of magnesium, from pumpkin seeds and spinach, to avocadoes and brown rice.

Perhaps the sweetest surprise on that list? Dark chocolate at 70 to 85 percent cocoa comes in at about 65 milligrams (mg) of magnesium per ounce, notes the U.S. Department of Agriculture. That makes an ounce a good source of the nutrient.

Citrus and Leafy Greens Offer Immune-Supportive Vitamin C

Vitamin C may help protect the body against oxidative stress, and that helps support immune function, says Palinski-Wade. Oxidative stress happens when there is an imbalance of healthy antioxidants and harmful substances called free radicals in the body, research shows. Oxidative stress is associated with an increased risk of various health conditions, including stroke, cancer and diabetes, one study suggests.

As a type of antioxidant, vitamin C is a free-radical scavenger and enhances immunity by supporting cellular function, among other benefits, notes one article.

Choose foods that are loaded with this vitamin. According to the NIH, foods with vitamin C include oranges, lemons, strawberries, blueberries, tomatoes, broccoli, leafy greens like kale, and bell peppers. To help retain vitamin C in your food, enjoy these foods in raw form when possible. Vitamin C is heat sensitive, so cooking can reduce the amount your body can take in, according to one study.

Nuts and Seeds Contain Vitamin E, Selenium, and Magnesium Which Are All Immunity Fortifiers

For a filling snack that’s also a boon to your immune system, reach for a handful of nuts or seeds. Not only do they have magnesium, they’re rich in vitamin E, an antioxidant that’s been shown to improve the body’s ability to fight off bacteria and viruses, according to the NIH. Plus, it doesn’t take much to get the benefits, Caldwell notes.

“Just one brazil nut packs more than 100 percent of your daily selenium needs.”

“It is a mineral that can strengthen your immune system,” she says. Indeed, according to the NIH, 1 oz of brazil nuts (about six to eight nuts) provides 989 percent of the DV of selenium.

One study noted that selenium plays a crucial role in immune response because the micronutrient helps regulate immune cell function and lowers inflammation.

Just a small handful of other options, such as sunflower seeds, almonds, walnuts, and pecans, can give you that vitamin E boost, and they’re a tasty addition to salads and other dishes as well, says Caldwell. They’re versatile, too, since you can roast them for a snack or make your own homemade nut flour.

One caveat to keep in mind is that portion control is essential when it comes to nuts. They’re a healthy food but are calorie dense, so over-indulgence can contribute to weight gain, says Caldwell.

If you’re not nuts for nuts, there’s plenty of vitamin E in wheat germ, vegetable oils, spinach, and broccoli as well.

Garlic and Onions Contain Potential Antiviral Properties

Garlic gets its distinctive smell from sulphur compounds, says Palinski-Wade, and whether or not you love the aroma, it offers protective benefits to your health and immune response, she says. That’s because when garlic is crushed or chopped, it produces allicin, which previous research has highlighted for its anti-viral and anti-bacterial properties.

Onions have a substance called quercetin, she adds, which may help regulate histamine response and also contains anti-viral properties.

Yogurt Aids Gut Health, Which May Positively Affect Immunity

“Yogurt is rich in probiotics, the good bacteria that supports gut health,” says Palinski-Wade. And a large proportion of the immune system is actually in the gastrointestinal tract.

In one study, participants without diabetes who ate yogurt daily saw an increase in protective immune function compared with the control group. To avoid added sugar, choose plain, unsweetened yogurt. Plain Greek yogurt is also an excellent source of protein and a good substitute for sour cream.

Not a yogurt fan? Try other fermented foods instead. One study details a clinical trial of 36 adults given two different diets, chosen because both have shown benefits for gut health, and researchers wanted to determine which would be most useful. The group who ate or drank fermented foods and drinks like yogurt, kimchi, kefir, and kombucha showed less inflammation compared with a group assigned to a high fibre diet alone, and had more diversity in their digestive systems’ beneficial bacteria.

Other fermented foods and fibre found in whole grains, legumes, fruit and vegetables are prebiotics which feed the probiotics in our gut and help them survive.

Other Tips to Boost Your Immune System

Let’s say you load up on all this good stuff and still get socked with a virus. It happens. But continuing with healthy eating will shorten the duration of symptoms if you have a mild case of whatever you’ve caught, says Caldwell.

Keep Eating

“Most important is continuing to eat enough food overall,” Caldwell notes. “We might not be able to totally prevent getting sick by eating well, but if you’re not getting enough nutrients, and especially not enough protein, you’re going to lack the energy to fight it off.”

Skip the Added Sugar and Unhealthy Fats

Also, avoid added sugar when you can. Added sugar is packed into soda drinks, juices, cakes, sweets, and biscuits, notes the American Heart Association. It can trigger inflammation in the body, and when your system is fighting inflammation, your immune system may not have enough power to combat outside stressors such as pathogens and viruses.

“In addition, high amounts of saturated fat and trans fat in the diet can increase inflammation in the same way, and that weakens the immune response,” says Palinski-Wade.

Drink More Water

“Stay hydrated” has become the mantra in everything from losing weight to boosting energy, and it does provide some magic for improving health overall, says Tiffany DeWitt, RD, a senior research scientist at healthcare company Abbott in Columbus, Ohio.

Proper hydration levels can help multiple bodily systems, including immunity, research shows. Also, Mayo Clinic notes, if you’re already on the cusp of a cold, water can loosen congestion.

Your best bet is water, says DeWitt. Electrolytes from beverages like zero-sugar Gatorade can be helpful for allowing your body to absorb fluids better, she adds, but you can also get these through foods without artificial sweeteners, such as bananas, avocadoes, Greek yogurt, nuts, kale, and spinach.

Enjoy Your Food

Whether you’re feeling under the weather or not, eating mindfully can be helpful, simply because you’ll slow down, feel less rushed, and truly enjoy your food, Caldwell says. Stress is linked to poor immune function, research has shown, so see your meals as a chance to chill.

Healthy eating can boost your immunity, and it can lift your spirit and nourish your sense of wellbeing too.