17 Immune-Boosting Foods to Help You Fight Off Viruses

|Updated Dec 19, 2022
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Why do we all need to know the best foods to boost the immune system? Because while we all are so over COVID-19, unfortunately, COVID is not done with us. Plus, it's flu season, so it only makes sense to supply your immune system with everything it needs to defend itself against any virus.

COVID and other viruses leave you tired, stuffed up, and off your game. Even a mild case is a drag, so now is the time to strengthen your immune system by eating all the right foods, getting sleep, exercising, and taking care of yourself. Here are the 17 best foods to choose to help you stay healthy all winter long by boosting your immune system.

There are simple things you can do to supply your killer T cells and other immune responses with all the ammo required to fight off viruses. Eat healthy and incorporate into your daily diet the best immunity foods that have been shown to help fight off COVID, both before or after you are exposed.

Below is a list of the best immune-boosting foods to add to your diet. To further strengthen your immune system get plenty of sleep, fit in your daily exercise, and do all the self-care rituals that help you relieve stress.

A Plant-Based Diet and COVID

Soon after the first wave of the pandemic hit, doctors and immunological experts began to recommend that their patients most vulnerable to serious symptoms (with a pre-existing condition or who have diabetes or lung conditions) switch to a mostly plant-based diet, which is known to bolster up the immune system.

One doctor urged his patients to eat mostly fruit and vegetables and stay away from inflammation-causing meat, dairy, and processed food, in light of COVID-19. And of course, get the vaccinations and boosters that are available to you.

The Best Immune-Boosting Foods to Eat

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1. Apples

Apples are the reigning prince of fruit when it comes to fiber, with 4.4 grams per fruit, which helps shift your microbiome to lower inflammation and fight diseases from heart disease to diabetes and even cancer. The more fiber in your diet, the more your immune cells can sweep for "other problems" including attacking agents like viruses or other infections.

To understand the role of soluble fiber and immunity, scientists studied how fiber can help shift the gut microbiome to lower inflammation in the body and strengthen immunity in a study that showed the immune cells "change" from having to work on inflammatory diseases to instead focus on invaders from outside.

"Soluble fiber changes the personality of immune cells – they go from being pro-inflammatory, angry cells to anti-inflammatory, healing cells that help us recover faster from infection," said Gregory Freund, a professor at the U of Illinois College of Medicine. This happens because soluble fiber causes increased production of an anti-inflammatory protein.

How much soluble fiber to eat in a day: The recommended amount is that women need at least 25 grams of fiber a day and men should get at least 38 grams of fiber a day, but more is better. An apple has more than 4 grams of fiber, but you can also get fiber from oats, as well as black beans, broccoli, pears, sweet potatoes, figs, avocados, nectarines, flax seeds, sunflower seeds as well as other fruits and vegetables.

2. Citrus Fruits

Your body does not produce vitamin C, which means you need to get it daily to have enough to create healthy collagen (the building blocks for your skin and healing). Also known as ascorbic acid, vitamin C is a water-soluble nutrient found in leafy greens and citrus, especially grapefruit, oranges, tangerines, lemons, limes, and clementines. It acts as an antioxidant, protecting cells from damage caused by free radicals.

How much vitamin C do you need a day? The recommended daily amount to shoot for is 65 to 90 milligrams a day, which is the equivalent of one small glass of orange juice or eating a whole grapefruit. Almost all citrus fruits are high in vitamin C. With such a variety to choose from, it's easy to get your fill.

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3. Red Peppers

Want even more vitamin C than that orange you eat every morning? Add red bell peppers to your salad or pasta sauce. One medium-sized red bell pepper contains 152 milligrams of vitamin C, or enough to fulfill your RDA.

Peppers are also a great source of beta carotene, a precursor of vitamin A (retinol). Vitamin A is important for healthy skin, mucous membranes, and your immune system. Beta carotene helps keep your eyes and skin healthy, as well. One cooked pepper has 19 percent of your daily recommended amount of beta carotene.
How much beta carotene do you need a day? You should try to get 75 to 180 micrograms a day which is the equivalent of one medium bell pepper a day. But a red pepper has more than two and a half times your RDA for vitamin C so eat them all winter long.

4. Broccoli

Broccoli may be the most super of all the superfoods on the planet. It's rich in vitamins A and C as well as being a good source of lutein, a powerful antioxidant, and sulforaphane, another potent antioxidant.

Broccoli also contains additional nutrients, including magnesium, phosphorus, zinc, lutein, and iron which support your immunity. Lutein is one of 600 known naturally occurring carotenoids and is found in high quantities in green leafy veggies such as spinach and kale.

There's another thing you need to know about broccoli, and why it's important to not overcook it. Broccoli contains sulforaphane, a compound that is a killer to a bug chewing on the stalk in the garden and equally deadly to "invaders" like viruses when they enter the body. Sulforaphane is a sulfur-rich compound found in several cruciferous vegetables like bok choy, cabbage, cauliflower, Brussels sprouts, and kale, but broccoli has the most.

How much should you eat in a day? There is no RDA for lutein, but experts say to get at least 6 milligrams. That means try to eat a half cup or more of broccoli a day. Throw it in sauces, salads, and grain bowls.

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5. Garlic

Garlic isn't just a great flavor enhancer, it's essential for your health. Ancient humans valued garlic as an infection fighter, which is why so much of our traditional diets include it as a first ingredient (making pasta sauce for instance). Value it and use it liberally for fighting infections.

Garlic’s immune-boosting properties are tied to its sulfur-containing compounds, such as allicin. Allicin is thought to improve your immune cells' ability to fight off colds and flu, and viruses of all kinds. (Smelling more garlic on the subway? It could be smart coronavirus management.) Garlic also has anti-microbial and anti-viral properties thought to fight off infections.

How much should you eat in a day: The optimal amount of garlic to eat is more than most of us can fathom: Two to three cloves a day. While that may not be doable, realistically, some people take garlic supplements to get 300 mg of dried garlic in a powdered tablet.

6.  Ginger

Ginger is another ingredient that has super properties when it comes to fighting off illness. It has been shown to decrease inflammation, which can help if you get swollen glands or a sore throat, or any inflammatory ailment.

Gingerol, the main bioactive compound in ginger, is a relative of capsaicin and can be used in sweet or spicy dishes. It has been found to alleviate pain and fight nausea, which is the reason ginger ale was given for upset stomachs, back when it contained actual ginger. Now few store-bought formulations do. Make your own ginger tea. Gingerol is responsible for many of its medicinal properties. It has powerful anti-inflammatory and antioxidant benefits.

How much ginger should you eat a day? Most recommendations land on 3–4 grams of ginger extract a day, or up to four cups of ginger tea, but no more than 1 gram a day if you are pregnant. Some studies have linked high dosages to an increased risk of miscarriage.

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7. Spinach

Spinach is not only packed with vitamin C but also antioxidants and beta carotene, both of which give your immune system the healthy boost it needs to fight off invaders.

Don't overcook your spinach, since the more it's cooked the less active the antioxidants will be. If you eat it raw or lightly steamed you'll keep more of the nutrients intact.

How much should you eat a day: Aim for 1 cup of fresh spinach or 1/2 cup cooked per day, but this is the right moment to try the raw or slightly wilted approach. Order warm or wilted spinach salad when you go out, or make it yourself with olive oil, pine nuts, and vegan parm.

8.  Almonds

Vitamin E in almonds will help ward off colds and flu and is key to your immune system humming along. It’s a fat-soluble molecule, meaning it requires the presence of fat to be absorbed, so nuts are the perfect package for E to make it into your system.

How many almonds should you eat in a day? A half-cup serving, or 46 whole, shelled almonds, provides almost 100 percent of your RDA of vitamin E. Almonds are great for you but they don't come with a  "free" pass, since 1/4 cup is a serving and has 162 calories, so double that for your RDA and you're eating about 325 calories. Throw them into smoothies instead.

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9. Turmeric

If you ever feel healthier eating curry, it is probably because of turmeric, which is an ingredient that gives it its burnt orange color. But this highly pigmented spice is known for its anti-inflammatory qualities. The ingredient curcumin has been found to decrease muscle soreness after a hard workout. How does it help immunity? decrease exercise-induced muscle damage.

How much turmeric should you eat in a day? Try adding extra turmeric to your diet during periods of stress or during flu season. Or take 500-2,000 mg of curcumin to help fight inflammation and power up your immune system.

10. Green Tea

Teas have been shown to help boost immunity and fight aging since they are packed with antioxidants and powerful phytochemicals. Whether you prefer green tea or black tea, you will benefit from the compounds called flavonoids, powerful antioxidants in most herbal teas. Green tea has high levels of EGCG, (epigallocatechin gallate) another hard-working antioxidant.

EGCG is known to boost immune function, and originally all tea leaves contain this anti-oxidant, but when black tea is fermented it deactivates most of the EGCG. Green tea is steamed so the EGCG is still active when you drink it.

Green tea also contains L-theanine, an anti-oxidant that appears to help in the production of T-cells in your body, the killer  L-theanine may aid in the production of germ-fighting compounds in your T-cells.

How much green tea should you drink in a day? The optimal amount is three to five cups in a day, but most people won't get to that level. Any amount is better than nothing. Swapping out a usual beverage daily for green tea could improve your health.

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11. Papaya

Papaya delivers over twice your recommended daily amount of vitamin C in one fruit –– though you're likely to eat a few slices on a salad or in a smoothie. It also contains an enzyme called papain that has anti-inflammatory effects, and inflammation is one factor in most illnesses, so avoiding it can help your body fight off bacterial infections like sinusitis.

Papayas contain potassium, vitamin B, and folate, which is a powerful cell rebuilder. Exactly how folic acid works to build immunity is linked to its role in protein synthesis, and researchers think that any mechanism in which cells proliferate can be affected (which is why it's critical for pregnant women). People who are folate-deficient have compromised immune systems.

How much folate should you eat a day: Whether you are pregnant or not, folate (vitamin B9) is a great vitamin to keep your cells healthy and strong. The recommendation is 400 micrograms a day, or get it from legumes, spinach, papayas, and avocados.

12. Kiwi Fruit

When you think of anti-oxidants, you should think of fruits that grow in the sun, since their vitamin pack comes from having to fight off the oxidation of the strong rays that beat down on them in the tropics. Kiwis are a great example. They are full of folate, vitamin K, vitamin C, and potassium.

These vitamins in combination work in the body to build healthy cells, fight infection and keep your immune system humming along. Vitamin K deficiency is rare but when people don't have enough they suffer from weak bones and compromised immune systems. The inflammation system in the body is also dependent on vitamin K, especially your killer T cells that mobilize and fight cancer and other diseases.

How much vitamin K should you eat in a day? Vitamin K is one of the unsung heroes of the body. Women should get 90 micrograms a day, and men should have 120 micrograms.

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13. Sunflower Seeds

Most seeds are filled with nutrients since they give the plant a healthy start. But sunflower seeds are especially healthy since they provide phosphorus, magnesium, and vitamin B-6 as well as vitamin E. Your immune system needs vitamin E to function at full throttle. You can also get vitamin E from avocados and spinach and broccoli.

How many sunflower seeds should you eat in a day? Anywhere from 1 ounce (30 grams) per day to a healthy handful is considered healthy, but because they are high in sodium you might want to refrain from eating the entire bag. The raw seeds have 204 calories per quarter cup.

14. Miso Soup or Paste

You've had miso soup at your favorite Japanese restaurant and perhaps even thought: "This tastes incredibly healthy! If a bit salty." Both thoughts are true. Miso is a fermented paste that adds a salty umami flavor to many Japanese dishes and soups. Most miso is made in Japan, where the ingredient has been used since the eighth century.

Miso needs no preparation and adds a touch of saltiness to soups, marinades, and dressings. Some people credit miso as a factor in Japanese longevity. Japan has more centenarians per capita of the population than anywhere else in the world –– and Japan has one of the lowest rates of obesity.

The nutrients in miso, which is a soybean paste that has been fermented with salt and a koji starter, boost immune system function by delivering healthy probiotics to the gut, making your microbiome healthier. How does Miso benefit your immune system?  It is a "SIRT" food, which are foods that contain high levels of ‘sirtuins’ or proteins that regulate cells and activate metabolism. A diet high in sirts is believed to lead to weight loss, increased wellness, and longevity.

How much miso should you eat in a day? Researchers believe that consuming one bowl of miso soup per day, as is the tradition in Japan, lowers the risks of breast cancer. Other than its high sodium content there is no reason to stay away from miso with all its varied health benefits. We say cheers to that.

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15. Blueberries

Nothing helps your body fight off infection better than a bowl of mixed berries, especially blueberries, which contain powerful antioxidants that give the fruit its vibrant color.

Blueberries contain a flavonoid called anthocyanin, which helps boost your immune system and fight off systemic stress of any kind including toxins.

In a recent study, researchers found that flavonoids play an essential role in your respiratory tract’s immune defense system, especially helpful in the case of infections that target the lungs such as COVID-19. People who eat a diet rich in flavonoids are less likely to get sick from an upper respiratory tract infection, or common cold than those who don't eat berries regularly.

How many blueberries should you eat? Get one cup of berries a day in a smoothie or bowl, as a snack or dessert. The calories burn slowly thanks to the fiber in the fruit, so you can eat them and not worry about a spike in blood sugar.

16. Mushrooms

Mushrooms have been shown to help support the immune system, in study after study. They are high in antioxidants like selenium that help support immune function and protect your cells from disease-causing damage. Mushrooms are also a rich source of vitamin D, which is critical for the immune system and lower levels of vitamin D have been tied to worse symptoms of COVID.

All mushrooms contain vitamin D and some mushrooms increase their vitamin D levels when exposed to sunlight or UV light, according to the Mushroom Council. The nutrients found in mushrooms have also been shown to suppress growth and help prevent the recurrence of hormone-dependent breast cancers, studies have shown.

How many mushrooms to eat in a day? Even just adding one small mushroom a day was linked to a decrease in the risk of breast cancer. When it comes to immunity, the more mushrooms you eat the healthier you'll be.

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17. Carrots

Beta carotene is one of the "server" antioxidants that helps your body use vitamin A, which is a vital nutrient for cell growth and in supporting your eyes, heart, lungs, and kidney function. A large carrot contains six milligrams of beta carotene, enough to convert to 1,000 mcg of vitamin A.

How many carrots to eat in a day? You can eat carrots or drink carrot juice. One study showed that drinking 16 ounces of carrot juice a day for three months helped to significantly increase the total antioxidant profile and lowered markers for inflammation, heart disease, and blood pressure. Carrot seeds and extract have been shown to have powerful anti-bacterial and anti-fungal properties.

 Bottom Line: Eat These Immunity-Boosting Foods to Fight Viruses.

The fact that COVID is hanging around means that we should eat immune-boosting foods daily and do everything possible to boost our immune system. Try incorporating these 17 foods that have been shown to strengthen your immune system, and help you be stronger and healthier on a cellular level.

For more research-backed advice, visit The Beet's Health & Nutrition articles