12 Healthy Foods to Support Your Immune System
List of Foods to Support Your Immune System
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, 2) 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. Studies have found that higher blood selenium levels are associated with an enhanced immune response (3).
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.
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.
Berries are an excellent source of immune essential vitamin C, along with many protective antioxidants. Vitamin C stimulates 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.
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).
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.
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).
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 vitamins C, E and beta-carotene.
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).
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 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.
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).
12Nuts and Seeds
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).
Data Sources and References
- Cardoso BR, Duarte GBS, Reis BZ, Cozzolino SMF. Brazil nuts: Nutritional composition, health benefits and safety aspects. Food Res Int. 2017 Oct;100(Pt 2):9-18.
- Jun Yang, Brazil nuts and associated health benefits: A review. LWT - Food Science and Technology, Volume 42, Issue 10, 2009, Pages 1573-1580
- Rayman MP. Selenium and human health. Lancet. 2012 Mar 31;379(9822):1256-68.
- Estrada A, Yun CH, Van Kessel A, et al. Immunomodulatory activities of oat beta-glucan in vitro and in vivo. Microbiol Immunol 1997;41:991-8.
- Maldonado Galdeano C, Novotny Nuñez I, Carmuega E, de Moreno de LeBlanc A, Perdigón G. Role of probiotics and functional foods in health: gut immune stimulation by two probiotic strains and a potential probiotic yoghurt. Endocr Metab Immune Disord Drug Targets. 2015;15(1):37-45.
- Parvez S, Malik KA, Ah Kang S, Kim HY. Probiotics and their fermented food products are beneficial for health. J Appl Microbiol. 2006 Jun;100(6):1171-85.
- Ashraf R, Shah NP. Immune system stimulation by probiotic microorganisms. Crit Rev Food Sci Nutr. 2014;54(7):938-56.
- Carr AC, Maggini S. Vitamin C and Immune Function. Nutrients. 2017 Nov 3;9(11):1211.
- Amir Aslani B, Ghobadi S.Studies on oxidants and antioxidants with a brief glance at their relevance to the immune system. Life Sci. 2016 Feb 1;146:163-73.
- Santos MS, Meydani SN, Leka L, et al. Natural killer cell activity in elderly men is enhanced by beta-carotene supplementation. Am J Clin Nutr1996;64:772-7.
- Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013 Jan 31;(1):CD000980.
- Keegan RJ, Lu Z, Bogusz JM, Williams JE, Holick MF. Photobiology of vitamin D in mushrooms and its bioavailability in humans. Dermatoendocrinol. 2013 Jan 1;5(1):165-76.
- Cardwell G, Bornman JF, James AP, Black LJ. A Review of Mushrooms as a Potential Source of Dietary Vitamin D. Nutrients. 2018;10(10):1498. Published 2018 Oct 13.
- Kapusta-Duch J, Kopeć A, Piatkowska E, Borczak B, Leszczyńska T. The beneficial effects of Brassica vegetables on human health. Rocz Panstw Zakl Hig. 2012;63(4):389-95.
- Mahn A, Castillo A.Potential of Sulforaphane as a Natural Immune System Enhancer: A Review. Molecules. 2021;26(3):752. Published 2021 Feb 1.
- Kaczmarek JL, Liu X, Charron CS, Novotny JA, Jeffery EH, Seifried HE, Ross SA, Miller MJ, Swanson KS, Holscher HD. Broccoli consumption affects the human gastrointestinal microbiota. J Nutr Biochem. 2019 Jan;63:27-34.
- Marco ML, Heeney D, Binda S, Cifelli CJ, Cotter PD, Foligné B, Gänzle M, Kort R, Pasin G, Pihlanto A, Smid EJ, Hutkins R. Health benefits of fermented foods: microbiota and beyond. Curr Opin Biotechnol. 2017 Apr;44:94-102.
- Josling P. Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. Adv Ther. 2001 Jul-Aug;18(4):189-93.
- Nantz MP, Rowe CA, Muller CE, Creasy RA, Stanilka JM, Percival SS. Supplementation with aged garlic extract improves both NK and γδ-T cell function and reduces the severity of cold and flu symptoms: a randomized, double-blind, placebo-controlled nutrition intervention. Clin Nutr. 2012 Jun;31(3):337-44.
- Gutiérrez, S.; Svahn, S.L; Johansson, M.E. Effects of Omega-3 Fatty Acids on Immune Cells. Int. J. Mol. Sci. 2019, 20, 5028.
- Wessels I, Maywald M, Rink L. Zinc as a Gatekeeper of Immune Function. Nutrients. 2017 Nov 25;9(12):1286.
- Read SA, Obeid S, Ahlenstiel C, Ahlenstiel G. The Role of Zinc in Antiviral Immunity. Adv Nutr. 2019 Jul 1;10(4):696-710.
- Lewis ED, Meydani SN, Wu D. Regulatory role of vitamin E in the immune system and inflammation. IUBMB Life. 2019 Apr;71(4):487-494.