Your diet can significantly affect the health and functioning of your immune system. The immune system is a network that protects your body from harmful bacteria, toxins, parasites, and viruses.
Choosing foods rich in vitamins, minerals, fatty acids, and other nutrients necessary for immune function can help keep your body healthy. Eating more immune-boosting foods can be especially beneficial during cold and flu season, which is typically during the fall and winter.
Kale is a green leafy vegetable that belongs to the cruciferous vegetable family. Kale is rich in nutrients that may enhance immune function, such as vitamin C, manganese, magnesium, folate, and provitamin A carotenoids.
Kale is high in folate, a nutrient that supports the production of T-cells. T-cells, also called killer T-cells, are white blood cells that attack foreign cells in the body, such as cancer cells and cells infected with viruses.
Consuming excess folate, such as with supplements, can deplete T-cells—which is why it's best to get the nutrient through food. A cup of cooked kale provides 19% of the Daily Value (DV) for folate.
Kale is also high in antioxidants with immune-supportive properties, such as polyphenols like quercetin. Quercetin has antiviral effects and can suppress inflammatory-causing proteins, such as tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β). These effects help support immune function.
2. Citrus Fruits
Citrus fruits, like oranges, lemons, and limes, are excellent sources of vitamin C.Vitamin C functions as a powerful antioxidant in your body, protecting your cells against damage caused by unstable molecules called free radicals.
Vitamin C plays many important roles in immune health. It's necessary for the function of white blood cells, which regulate inflammation and defend the body against bacteria and viruses.
A medium orange (about 140 grams) covers 70% of the DV for vitamin C.
Citrus fruits contain additional plant compounds, like flavonoids, that may support immune health by lowering inflammation. The immune system uses acute (short-term) inflammation to promote healing during injury or infection. However, chronic (ongoing) inflammation can harm the body and immune system. Anti-inflammatory foods can help prevent chronic inflammation.
Like kale, broccoli belongs to the cruciferous vegetable family. This vegetable is loaded with immune-supportive nutrients, such as vitamins B6 and C, folate, and provitamin A.
One cup of cooked broccoli covers over 100% of the DV for vitamin C, 18% for vitamin B6, and 42% for folate. B6 and folate both support white blood cell activity, antibody production, and the growth and function of T cells, which protect the body against infection.
Broccoli also contains glucosinolates, which are sulfur compounds that the body converts into molecules called isothiocyanates. Isothiocyanates may promote immune health by reducing inflammation and helping the body fight infections.
4. Eggs
Eating enough protein is essential for immune health because protein is necessary for producing antibodies and cytokines. Cytokines are proteins essential to immune system function that help protect against illness and infection.
Eggs are rich in protein, providing 6.3 grams per large egg—about 12% of your DV. They also provide vitamins and minerals essential to immune health, such as vitamins A and B12, zinc, iron, and selenium.
Two large eggs cover over 50% of your DV for selenium, a mineral that the body uses to create special proteins called selenoproteins. Selenoproteins have powerful antioxidant and anti-inflammatory activity and regulate immune response. Maintaining optimal selenium levels can protect you against infection and support optimal immune function.
Sardines are an excellent source of the anti-inflammatory omega-3 fats eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These fatty acids have immune-enhancing properties. Omega-3s regulate inflammation, supporting overall immune system function and helping the body fight viral infections.
Sardines also provide other nutrients essential to immune function, such as protein, selenium, zinc, and iron.
A 3.75-ounce can of sardines covers 15% of the DV for iron. Iron is a mineral that regulates immune response and the function and production of neutrophils, which are white blood cells that help your body fight off infection. This is why iron deficiency can negatively affect your immune health and make you more vulnerable to getting sick.
6. Sweet Potatoes
Sweet potatoes are rich in provitamin A carotenoids, such as beta-carotene. The body converts beta-carotene into active forms of vitamin A, which are necessary for overall immune function.
Vitamin A is important for the development and function of lymphocytes, a white blood cell that fights off disease-causing bacteria and viruses.
Carotenoids also act as powerful antioxidants, protecting your cells against damage that may otherwise lead to disease. Studies show that carotenoids may help reduce inflammation and cellular damage caused by viruses like COVID-19.
Liver, an organ meat, is a rich source of protein, B vitamins, vitamin A, iron, and many other nutrients needed for optimal immune function.
Liver is exceptionally high in vitamin A, with a 3.5-ounce serving covering over 800% of your DV. It's also an excellent source of riboflavin (B2), a vitamin with antioxidant and anti-inflammatory activity needed for T cell production and activity. The same serving of liver covers over 200% of your DV for riboflavin.
8. Strawberries
High in vitamin C and folate, strawberries are an excellent choice for supporting your immune system during cold and flu season. One cup of sliced strawberries covers over 100% of the DV for vitamin C and just under 10% of your daily folate needs.
Strawberries are also high in protective plant compounds, such as flavonoids, which support the immune system by regulating inflammation and enhancing immune response.
Oysters are packed with health-boosting minerals like zinc and selenium. A 100-gram serving of oysters covers 118% of the DV for selenium and 128% for zinc.
Zinc is necessary for T cell development and the normal functioning of the immune system. A zinc deficiency can decrease the number and activity of lymphocytes (disease-fighting white blood cells), making you more susceptible to infection.
Oysters also provide omega-3 fatty acids, B vitamins, and other nutrients needed for immune health.
10. Pumpkin Seeds
Though small in size, pumpkin seeds provide an impressive amount of vitamins and minerals that play essential roles in immune function.
Pumpkin seeds are a good source of zinc, vitamin E, and manganese, all of which are needed for immune function.
A 1-ounce serving of pumpkin seeds provides 56% of the DV for manganese. This mineral boosts the production and activity of immune cells that fight infections, such as myeloid and natural killer cells.
Blueberries contain several antiviral compounds, such as proanthocyanidins. Blueberry proanthocyanidins may protect against the Aichi virus (AiV), a stomach virus that causes fever, diarrhea, vomiting, nausea, and abdominal pain.
Blueberries are also high in immune-supportive vitamin C, with a one-cup serving covering 16% of the DV.
12. Chicken
Chicken is an excellent source of protein, which your body breaks down into amino acids. Amino acids, such as arginine and glutamine, are essential for overall immune function.Amino acids regulate the activation of white blood cells like lymphocytes, natural killer cells, and macrophages, which protect your body from getting sick and fight infection.
Chicken provides zinc, selenium, and B vitamins, which are also necessary for immune response.
Consuming more probiotic-rich foods can be an effective way to support your immune system. The gut is an important part of your immune system, with 70–80% of immune cells located in your digestive tract.
Foods high in probiotics, like kefir, help support the growth of protective bacteria in your gut and support a healthy immune response.
Kefir is also a good source of immune-supportive nutrients like protein,selenium, and zinc.
14. Sunflower Seeds
Sunflower seeds are one of the highest food sources of vitamin E. A 1-ounce serving (about 2 tablespoons) of shelled sunflower seeds covers nearly 50% of the DV.
Vitamin E supports antibody production and the activity of natural killer cells. It also has strong antioxidant and anti-inflammatory properties. Maintaining optimal levels of vitamin E may reduce your risk of developing certain illnesses, like respiratory infections.
Salmon is rich in omega-3 fatty acids and vitamin D, both of which are needed for immune health. Vitamin D supports the production of antimicrobial proteins in the immune system, including cathelicidin and β-defensin. These proteins protect your body against bacteria, viruses, and fungi.
Vitamin D deficiency can negatively affect immune function, and studies show that low vitamin D levels increase infection risk. Half of a salmon filet (178 grams) covers over 100% of the DV for vitamin D, making salmon a smart choice for immune health.
16. Garlic
Compounds found in garlic, such as allicin and diallyl sulfide, have potent antiviral, antibacterial, and anti-inflammatory effects. Adding more garlic to your diet can support your immune system and may reduce your risk of getting sick.
Studies show garlic may help enhance immune activity, fight pathogens (germs) that cause respiratory infections, and reduce symptoms of viral infections, such as the flu and the common cold.
In addition to following a well-rounded diet and eating more immune-supporting foods, there are other ways to support your immune health.
Here are tips for keeping your immune system strong:
- Stay active: Getting regular exercise can help support overall immune health and may reduce your risk of becoming severely ill from the flu.
- Maintain a healthy weight: Body weight can influence immune health. People with obesity may have impaired immune function and be less responsive to flu vaccines.Being underweight can also weaken your immune system and raise infection risk.
- Get enough sleep: Getting the recommended 7-9 hours of sleep per night can help keep your immune system healthy, while sleep deprivation can increase your chances of becoming sick.
Avoiding smoking and excessive alcohol consumption are other ways to care for your immune health and decrease infection risk.
A Quick Review
Many foods, like citrus fruits, eggs, berries, garlic, kefir, broccoli, salmon, and kale, contain nutrients necessary for maintaining a healthy immune system.
Zinc, selenium, iron, and vitamins A, B, C, and E are all important for immune health. Amino acids found in protein, omega-3 fatty acids, and protective plant compounds also support overall immune response.
In addition to eating a well-balanced diet, implementing habits like regular exercise, maintaining a healthy weight, and sleeping 7-9 hours per night can help you stay healthy through cold and flu season.
