12 Healthy Foods to Support Your Immune System

Photo of Daisy Whitbread Written by Daisy Whitbread
BSc (Hons) MSc DipION
Photo of Dr. Thomas Kutner Medically Reviewed by
Dr. Thomas Kutner
Evidence Based. References sourced from PubMed.
12 Healthy Foods to Support Your Immune System

The immune system is a complex network of cells, organs, and tissues that work together to protect us against disease. When the immune system is weakened, we are more vulnerable to catching any 'bugs' that are going around; this includes common colds, flu, and other viruses.

Nutrition plays a vital role in keeping the immune system healthy. Current research shows that more than 20 different nutrients are necessary to keep the system functioning at its best. Vitamin A, vitamin C, vitamin D, vitamin E, zinc, selenium, and probiotics are among the most well-known and well-researched.

No single food can 'boost' the immune system, however, there are foods that, as part of a varied and balanced diet, can provide some of the key nutrients it requires. Foods that support your immune system function and overall health include brazil nuts, oatmeal, yogurt, berries, sweet potatoes, bell peppers, mushrooms, and more...

List of Foods to Support Your Immune System

1 Brazil Nuts
Brazil Nuts
Brazil nuts are by far the best dietary source of selenium, containing around 100 times more than other nuts and providing more than the recommended daily allowance in a single nut! (1) Selenium is essential for immune system function and has many roles in immunity, including enabling a type of white blood cell, called neutrophils, to defend us against invading pathogens. (2) Studies have found that higher blood selenium levels are associated with an enhanced immune response. (3)
2 Oatmeal
A bowl of oatmeal with blueberries
Oats contain a special type of soluble fiber called beta-glucans, which may stimulate the immune system to help protect us against bacterial and viral infections. Preliminary research (in test tubes and animals) has shown that beta-glucans activates certain types of white blood cells. (4) Oats are a healthy addition to any diet; they also provide immune system essentials selenium and zinc, along with several other minerals, B vitamins, and fiber.
3 Natural Yogurt
Bowl of Yogurt with Raspberries
Live, natural yogurt contains beneficial bacteria called probiotics, which help keep the gut healthy. The balance of bacteria in our gut influences many aspects of health including our immunity. (5,6,7) 70% of our immune system is in fact, thought to be located in the gut, and increasing the numbers of beneficial bacteria here, strengthens our body?s defenses. Choose natural, unsweetened (preferably organic) yogurt to avoid added sugar, sweeteners, and other additives.
4 Berries
Strawberries and blueberries
Berries are an excellent source of immune essential vitamin C, along with many protective antioxidants. Vitamin C is integral to the immune system by enhancing the activity of various immune cells (8) and functions as an antioxidant itself. When the immune system fights invading organisms, free radicals are produced and these must be neutralized by antioxidants to prevent them from causing harm. (9) A constant supply of vitamin C and other antioxidants is thus beneficial for a healthy immune system.
5 Sweet Potatoes
Sweet Potato
Sweet potatoes are a top dietary source of immune system 'hero' beta-carotene. This nutrient has double immune-enhancing actions, both as beta-carotene itself and vitamin A, into which it is converted in the body. Vitamin A deficiency is well known to lead to an impaired ability to fight off infections. Beta-carotene supports and protects the immune system further via antioxidant effects and by increasing immune cell numbers and activity. (10)
6 Bell Peppers
Bell peppers
Bell peppers (capsicum) are a top source of two immune essentials: vitamin C and beta-carotene. Just half an average red pepper contains 150% of your daily value for vitamin C. Studies have shown that vitamin C (as high dose supplements) can slightly reduce the severity of the common cold and help you recover more quickly. (11) Other top sources of vitamin C are strawberries, guavas, kiwi, kale, broccoli, citrus fruits, tomatoes, and papaya plus all other fruits and vegetables.
7 Mushrooms
Crimini mushrooms
Mushrooms are a great source of several key nutrients that support immune function including beta-glucans, selenium, and zinc. Mushrooms also contain a small amount of vitamin D, but can provide much higher amounts if they are exposed to sunlight or UV light before consumption. (12) This is achieved if they are grown outside, treated with UV by growers, or simply by putting them out in the sun for a few hours yourself! Mushrooms exposed to UV are the only vegetarian source that naturally provide substantial amounts of bioavailable vitamin D. (13)
8 Broccoli
Broccoli
Broccoli contains many beneficial phytochemicals (natural substances found in plants) with antioxidant and anti-inflammatory effects. (14) Sulforaphane, one of these phytochemicals, has recently been generating scientific interest regarding its positive effects on immune function and ability to defend against viruses. (15) Regular consumption of broccoli may also favorably influence the composition of the gut bacteria. (16) Broccoli is also an excellent source of vitamin C, vitamin E, and beta-carotene.
9 Fermented Foods
Kimchi in a bowl
Fermented foods like sauerkraut and kimchi are another top source of natural probiotics to support healthy digestive and immune systems. The beneficial bacteria in fermented foods help keep the lining of the digestive tract strong and healthy, which in turn reduces the chances of harmful substances entering the body. These ?friendly? bacteria support various aspects of immune function including antibody function. Other great fermented foods to try are kombucha (fermented tea), tempeh (fermented soya beans) and miso. (17)
10 Garlic
A clove of garlic
Garlic provides mild antiviral, antibacterial, and antiseptic properties and is described as 'nature?s own antibiotic'. Taking garlic supplements over winter was shown in one study to reduce the chances of catching a cold by 63% and to speed up recovery in those who were infected. (18) In another study, aged garlic extract was shown to stimulate the proliferation of two kinds of immune cells (natural killer cells and T-cells), resulting in reduced severity of colds and flu. (19) Crushing garlic and eating it raw or lightly cooked will retain its potency.
11 Oily Fish
Salmon Fillets
Oily fish is the best naturally occurring dietary source of omega-3 fats and vitamin D, along with being a good source of selenium, B vitamins, antioxidants and protein. Omega-3 fats regulate inflammation in the body, an important process in our "innate" (inbuilt) immunity. In addition, omega-3 fats have a structural role in cell membranes, helping cells, including those involved in immunity, communicate and function more effectively. In addition, omega-3 fats have been shown to have direct effects on various cells of the immune system. (20)
12 Nuts and Seeds
Nuts and Seeds in a Bowl
Seeds are a top source of both zinc and vitamin E, two key nutrients for immune system function. Zinc has been described as the 'gatekeeper of immune function', due to its role in regulating immune responses. (21) Zinc aids wound healing is required for white blood cell production and stimulates antiviral immune mechanisms. (22) The body cannot store zinc, so a regular supply in the diet is essential. Vitamin E is an antioxidant found in particularly high concentrations in immune cells and has been shown to support immune function and reduce the risk of infections, especially in older people. (23)
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Data Sources and References

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  2. Avery JC, Hoffmann PR. The role of selenium in inflammation and immunity: from molecular mechanisms to therapeutic opportunities Nutrients. 2018 Sep 1;10(9):1203. doi: 10.3390/nu10091203. 30200430
  3. Kong Z, Xia Z. Selenium and human health Lancet. 2012 Aug 4;380(9840):471; author reply 471-2. doi: 10.1016/S0140-6736(12)61287-2. 22863048
  4. Yun CH, Estrada A, Van Kessel A, Gajadhar A, Redmond M, Laarveld B. Immunomodulatory activities of oat beta-glucan in vitro and in vivo Microbiol Immunol. 1998;42(6):457-65. doi: 10.1111/j.1348-0421.1998.tb02309.x. 9688080
  5. Mani-López E, Palou E, López-Malo A. Role of probiotics and functional foods in health: gut immune stimulation by two probiotic strains and a potential probiotic yoghurt J Dairy Sci. 2014 May;97(5):2578-90. doi: 10.3168/jds.2013-7551. 24745665
  6. Kopp-Hoolihan L. Probiotics and their fermented food products are beneficial for health J Am Diet Assoc. 2001 Feb;101(2):229-38; quiz 239-41. doi: 10.1016/S0002-8223(01)00060-8. 11271697
  7. Prescott SL, Wickens K, Westcott L, Jung W, Currie H, Black PN, Stanley TV, Mitchell EA, Fitzharris P, Siebers R, Wu L, Crane J; Probiotic Study Group. Immune system stimulation by probiotic microorganisms Clin Exp Allergy. 2008 Oct;38(10):1606-14. doi: 10.1111/j.1365-2222.2008.03061.x. Epub 2008 Jul 2. 18631345
  8. Ströhle A, Wolters M, Hahn A. Vitamin C and Immune Function Inflamm Allergy Drug Targets. 2011 Feb;10(1):54-63. doi: 10.2174/187152811794352105. 21184650
  9. Valko M, Rhodes CJ, Moncol J, Izakovic M, Mazur M. Studies on oxidants and antioxidants with a brief glance at their relevance to the immune system Chem Biol Interact. 2006 Mar 10;160(1):1-40. doi: 10.1016/j.cbi.2005.12.009. Epub 2006 Jan 23. 16430879
  10. Santos MS, Gaziano JM, Leka LS, Beharka AA, Hennekens CH, Meydani SN. Natural killer cell activity in elderly men is enhanced by beta-carotene supplementation Am J Clin Nutr. 1998 Jul;68(1):164-70. doi: 10.1093/ajcn/68.1.164. 9665110
  11. Douglas RM, Hemilä H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold Cochrane Database Syst Rev. 2007 Jul 18;(3):CD000980. doi: 10.1002/14651858.CD000980.pub3. 17636648
  12. Cardwell G, Bornman JF, James AP, Daly A, Dunlop E, Dabos G, Adorno P, Black LJ. Photobiology of vitamin D in mushrooms and its bioavailability in humans Foods. 2023 Mar 28;12(7):1429. doi: 10.3390/foods12071429. 37048250
  13. S?awi?ska A, Fornal E, Radzki W, Skrzypczak K, Zalewska-Korona M, Michalak-Majewska M, Parfieniuk E, Stachniuk A. A Review of Mushrooms as a Potential Source of Dietary Vitamin D Food Chem. 2016 May 15;199:203-9. doi: 10.1016/j.foodchem.2015.11.131. Epub 2015 Nov 30. 26775962
  14. Johnson IT. The beneficial effects of Brassica vegetables on human health Proc Nutr Soc. 2007 May;66(2):207-15. doi: 10.1017/S0029665107005459. 17466103
  15. Bai Y, Wang X, Zhao S, Ma C, Cui J, Zheng Y. Potential of Sulforaphane as a Natural Immune System Enhancer: A Review Oxid Med Cell Longev. 2015;2015:407580. doi: 10.1155/2015/407580. Epub 2015 Oct 25. 26583056
  16. Charron CS, Vinyard BT, Ross SA, Seifried HE, Jeffery EH, Novotny JA. Broccoli consumption affects the human gastrointestinal microbiota Br J Nutr. 2018 Dec;120(12):1370-1379. doi: 10.1017/S0007114518002921. 30499426
  17. ?anlier N, Gökcen BB, Sezgin AC. Health benefits of fermented foods: microbiota and beyond Crit Rev Food Sci Nutr. 2019;59(3):506-527. doi: 10.1080/10408398.2017.1383355. Epub 2017 Oct 20. 28945458
  18. Van Straten M, Josling P. Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey Adv Ther. 2002 May-Jun;19(3):151-9. doi: 10.1007/BF02850271. 12201356
  19. Percival SS. Supplementation with aged garlic extract improves both NK and ??-T cell function and reduces the severity of cold and flu symptoms: a randomized, double-blind, placebo-controlled nutrition intervention J Nutr. 2016 Feb;146(2):433S-436S. doi: 10.3945/jn.115.210427. Epub 2016 Jan 13. 26764332
  20. Dendelé B, Tekpli X, Hardonnière K, Holme JA, Debure L, Catheline D, Arlt VM, Nagy E, Phillips DH, Ovrebø S, Mollerup S, Poët M, Chevanne M, Rioux V, Dimanche-Boitrel MT, Sergent O, Lagadic-Gossmann D. Effects of Omega-3 Fatty Acids on Immune Cells Chem Biol Interact. 2014 Jan 25;207:41-51. doi: 10.1016/j.cbi.2013.11.002. Epub 2013 Nov 15. 24246761
  21. Maywald M, Wessels I, Rink L. Zinc as a Gatekeeper of Immune Function Int J Mol Sci. 2017 Oct 24;18(10):2222. doi: 10.3390/ijms18102222. 29064429
  22. Kumar A, Kubota Y, Chernov M, Kasuya H. The Role of Zinc in Antiviral Immunity Med Hypotheses. 2020 Nov;144:109848. doi: 10.1016/j.mehy.2020.109848. Epub 2020 May 25. 32512490
  23. Sen CK, Khanna S, Roy S. Regulatory role of vitamin E in the immune system and inflammation Ann N Y Acad Sci. 2004 Dec;1031:127-42. doi: 10.1196/annals.1331.013. 15753140
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