A Mayo Clinic Doctor’s Advice Part 3: Foods that Support Immune Health
A five-part series dedicated to workers on the front line.
I am often asked if the foods we eat can actually boost our body's immune system. My answer is a resounding "yes."
There's no doubt that a healthy diet is a good foundation for health and well-being. And during stressful times, eating well is more important than ever. Research shows that many common foods support your body when it's under siege from triggers such as stress or viruses.
But I believe food and diet have a much broader impact than just keeping your body strong. A meal made with care has the power to both nourish your body and lift your spirits.
I think most people can relate. As one shining example, many across the nation are purchasing gift certificates from restaurants that are used, in turn, to provide meals for hospital staff and first responders. In the middle of the tragedies surrounding COVID-19, we still find ways to care for one another.
Below is an overview of some foods that show good evidence for boosting immunity and decreasing inflammation. Mixed with a bit of care and kindness, they might provide just what you need at the moment. Bon appétit and thank you for your tireless service!
How to Boost Your Immune System through Diet
Research shows that several foods support the immune system and battle against the inflammation triggered by stress or common illnesses. Chances are you're already eating many of the following foods. If not, now is a good time to try something new.
- Garlic. Garlic is an effective antiviral, antifungal, and antibacterial,1 making it a go-to ingredient for a healthy immune system. Research shows that garlic helps reduce the severity of cold and flu symptoms.2 Chop or crush the cloves – which helps convert alliin to allicin, the protective element in garlic – and add to sauces, soups, appetizers, or whatever you're cooking.
- Red peppers. High in vitamin C, red bell peppers and hot chili peppers have antimicrobial properties that protect against viruses and other microorganisms.3
- Shiitake mushrooms. Eating shiitake mushrooms increases the levels of natural killer cells and immunoglobulin A, two important immune system components for fighting off viral attacks.4
Viruses, like the common cold and influenza, cause inflammation in the body. That inflammatory response is sometimes a double-edged sword: While it helps the body fight off infection, it can also cause serious problems that can contribute to lung damage and even death. Many research studies suggest that modulating the inflammatory response could be key to improving health outcomes.5
In addition, experiencing stress can cause an inflammatory response in the brain, which triggers the release of glucocorticoids, a class of steroid hormones.6 If you remain in a state of chronic stress, your body can suffer from long-term inflammation – which can increase the risk of heart disease7 and is associated with a higher risk of cancer, diabetes, and other chronic conditions.8-10 Foods that show anti-inflammatory properties include:
- Turmeric. A spice widely used in cooking in India and derived from a ginger-family perennial plant, turmeric packs a double punch as both an anti-inflammatory and an antioxidant.11 Turmeric provides a polyphenol known as curcumin. Polyphenols are a group of compounds high in antioxidants that are found in plant foods like fruits, vegetables, whole-grains, and nuts. Curcumin has been well studied for the health benefits it provides, including the ability to suppress inflammation and help manage conditions such as arthritis, anxiety, and exercise-induced muscle soreness.11 It has also been shown to help memory and mood.11
- Ginger. Available in powdered form or fresh in the produce section of grocery stores, ginger root contains a substance called gingerol, which has been shown to help inhibit inflammation.12 Some studies have found that gingerol improves cardiovascular disorders and gastrointestinal health and helps reduce exercise-induced muscle pain.12
- Fish and nuts. Omega-3 fatty acids – mostly found in fatty fish and some nuts – play an important role in regulating the body's inflammatory process.13 Research has shown that including omega-3s as part of your diet helps improve outcomes for a range of conditions like heart disease, kidney problems, and autoimmune disorders.13 Add these omega-3-rich foods to your shopping list:14
- Salmon, tuna, trout, and mackerel
- Walnuts, pecans, flaxseed, and chia seeds
- Plant oils, including soybean oil, flaxseed oil, and canola oil
- Foods fortified with omega-3s, including some eggs, juice, milk, and soy beverages
3. Gut microbiome boosters
Many research studies have explored the impact that diet can have on a healthy gut microbiome – the complex gastrointestinal ecosystem made up of trillions of viruses, fungi, bacteria, and other bugs. A healthy gut ecosystem supports the body's immune function.15 Because food directly affects these microorganisms, either encouraging or suppressing their growth, researchers have explored which foods support a healthy microbiome.16 Some of these foods include17:
- Fermented foods, including yogurt, sauerkraut, kombucha, and kefir
- Whole-grain, high-fiber foods
- Monounsaturated fats, such as olive oil
- Polyphenol-rich foods, including fruit, vegetables, seeds, tea, cocoa products, and wine
Generally, the Mediterranean diet, which includes healthy fatty acids, fruits, vegetables, fiber, and smaller amounts of protein, is associated with a healthier gut microbiome.17
4. Foods high in antioxidants
Antioxidants are necessary to decrease inflammation and fight off disease.10 They can be consumed in the foods you typically eat or from supplements.
Three key antioxidants – zinc and vitamins C and D – play crucial roles in helping protect the body's cells from damage.18 Learn more about which supplements can help support optimal immune function.
Antioxidants are commonly found in just about all types of fruit and dark, leafy greens. Most salad greens, kale, and spinach include vitamins A, C, E, K, and folate, as well as high levels of fiber and immune-supportive minerals.19 These foods are also low in carbs, sodium, and cholesterol, making them a quadruple win.19
Protect yourself with healthy food
When you're feeling stressed or sick, it's common to forgo eating a healthy diet. But eating the right foods can have a sizeable impact on boosting immunity and decreasing inflammation in your body.10
And the reverse is true, too: unhealthy foods – especially processed sugars – have been shown to increase levels of C-reactive protein, a biomarker of inflammation in the blood.20 There's no magic solution that will cure every virus – but a healthy diet is your best first line of defense.
Read the full five part series
Part 4: Sleep – Tips that Can Improve Your Quality of Sleep
Part 5: Physical Activity – Exercises that Boost Your Immune System and Reduce Inflammation
An important note: No dietary supplement can diagnose, treat, cure or prevent any disease, including COVID-19. With the ongoing COVID-19 pandemic, it is especially important to understand that no dietary supplement, no diet, and no lifestyle modifications – other than the recommended social distancing and hygiene practices – can prevent you from being infected with the COVID-19 virus. No current research supports the use of any dietary supplement to protect you from being infected with the COVID-19 virus.
- Harris J, Cottrell S, Plummer S, Lloyd D. Antimicrobial properties of Allium sativum (garlic). Appl Microbiol Birotechnol 2001;57:282-286.
- Nantz M, Rowe C, Muller C, et al. 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;31(3):337-344.
- Omolo M, Wong Z, Mergen A, et al. Antimicrobial properties of chili peppers. J Infect Dis Ther 2014;2:145 doi:10.4172/2332- 0877.1000145
- Dai X, Stanilka J, Rowe C, et al. Consuming Lentinula edodes (shiitake) mushrooms daily improves human immunity: A randomized dietary intervention in healthy young adults. J Am Coll Nutr 2015;34:478-87.
- Tavares L, Teixeira M, Garcia C. The inflammatory response triggered by influenza virus: a two edged sword. Inflamm Res 2016;66:283-302.
- Liu Y, Want Y, Jiang C. Inflammation: The common pathway of stress-related diseases. Front Hum Neurosci 2017;11:316. doi: 10.3389/fnhum.2017.00316.
- American Heart Association. 7272 Greenville Ave. Dallas, TX 75231. https://www.heart.org/en/health-topics/consumer-healthcare/what-is-cardiovascular-disease/inflammation-and-heart-disease [Accessed 4.23.20]
- National Cancer Institute. 31 Center Drive, Building 31, Bethesda, MD, 20814. https://www.cancer.gov/about-cancer/causes-prevention/risk/chronic-inflammation [Accessed 4.23.20]
- Pollack R, Donath M, LeRoith D, Leibowitz G. Anti-inflammatory agents in the treatment of diabetes and its vascular complications. Diabetes Care 2016;39:S244-S252.
- Minihane A, Vinroy S, Russell W, et al. Low-grade inflammation, diet composition and health: current research evidence and its translation. Br J Nutr 2015; 114:999-1012.
- Hewlings S, Kalman D. Curcumin: A review of its effects on human health. Foods 2017;6:92. doi:10.3390/foods6100092.
- Mashhadi N, Ghiasvand R, Askari G, et al. Anti-oxidative and anti-inflammatory effects of ginger in health and physical activity: Review of current evidence. Int J Prev Med 2013;4:S36-S42.
- Zivkovic A, Telis N, German J, Hammock B. Dietary omega-3 fatty acids in the modulation of inflammation and metabolic health. Calif Agric 2011;65:106-111.
- National Institutes of Health. 10 Center Dr., Bethesda, MD 20814. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/ [accessed 4.23.20]
- Shreiner A, Kao J, Young V. The gut microbiome in health and disease. Curr Opin Gastroenterol 2015;31:69-75.
- Zmora N, Suez J, Elinav E. You are what you eat: diet, health and the gut microbiota. Nat Rev Gastroenterol Hepatol 2018;16:35-56.
- Singh R, Chang H, Yan D, et al. Influence of diet on the gut microbiome and implications for human health. J Transl Med 2017;15:73. Doi 10.1186/s12967-017-1175-y
- National Center for Complementary and Integrative Health. 9000 Rockville Pike
Bethesda, MD 20892. https://www.nccih.nih.gov/health/antioxidants-in-depth. [accessed 4.23.20]
- USDA Agricultural Research Service. 1400 Independence Ave. S.W., Washington, DC 20250. https://www.ars.usda.gov/plains-area/gfnd/gfhnrc/docs/news-2013/dark-green-leafy-vegetables/ [accessed 4.23.20]
- Arthritis Foundation. 1355 Peachtree St NE, Atlanta, GA 30309. https://www.arthritis.org/health-wellness/healthy-living/nutrition/anti-inflammatory/increasing-fiber [accessed 4.23.20]