How Does Nutrition Affect the Immune System?
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From Theresa "Sam" Houghton, T. Colin Campbell Center for Nutrition Studies
March 2020

What you eat plays a big role in how well your immune system is able to wage war against invading viruses.

Viruses can affect every body system, including the respiratory tract, gastrointestinal tract, skin, liver and brain.[1] Cold and flu viruses are the most recognizable, with over 62 million cases of the common cold and an estimated 25 to 45 million cases of the flu plaguing the U.S. every year.[2][3] But your body is equipped with a powerful ally, the immune system, to fight viruses off and prevent future infections from taking hold.

What you eat plays a big role in how well your immune system is able to wage war against invading viruses. Here’s what you can do to make sure yours is in top shape and ready for action.

How Your Immune System Works to Fight Viruses

A strong immune response relies on multiple body systems and cell types working together to identify and remove viruses and other pathogens.

What is a virus?

Viruses are pieces of DNA or RNA that use host cells to make copies of themselves. When a virus enters your body, it injects its genetic material into your cells. Infected cells make more viral genes, which either “bud” off cell surfaces or build up inside cells until they burst.[4] Once new viral material is released, it goes on to infect other cells.

Innate and Adaptive Immunity

Invasion by a virus triggers your innate immune system. This generalized immune response helps your body get the infection under control but isn’t trained to target specific pathogens. That’s the job of adaptive immunity.

Adaptive immunity is mediated by T cells and B cells.[5] T cells start out in the bone marrow and migrate to the thymus gland to mature. B cells originate and mature in bone marrow. While T cells “patrol” the body on the lookout for invaders, B cells create antibodies against known pathogens. This allows your body to recognize and fight back against viruses it’s encountered before.

Different types of T cells coordinate the adaptive immune response with help from lymph tissues throughout the body, including gut-associated lymphoid tissue (GALT) in the digestive tract. When immune cells identify viruses and other pathogens, they move in to destroy the invaders and return your body to a state of health.

How to Boost Your Immune System Naturally

Your immune system is best prepared to take action against viruses when you choose foods that provide a steady stream of key nutrients. Diets centered around whole plant foods in particular appear to stimulate natural killer cell activity. Natural killer cells are part of the innate immune response that hones in on pathogens, including viruses responsible for common respiratory infections.[6]

Immune System Booster Foods

Some plant-based foods have properties that make them top choices for strengthening the immune system:

• Mushrooms, particularly medicinal varieties like chaga, contain antioxidants and polysaccharides to regulate immunity and reduce inflammation.
• Fruits and vegetables, the brighter the better! Vibrant colors signal the presence of antioxidant and anti-inflammatory phytochemicals like carotenes, polyphenols, flavonoids and anthocyanidins.
• Bitter greens like dandelion and arugula promote liver health to support robust natural killer cell production and proper T cell function.[7][8]
• Whole grains and legumes provide fiber for a healthy gut. Since the gut is a major center of immune activity, it’s important to keep it balanced! These foods also contain B vitamins and zinc for added immune support.
• Flax seeds are a good source of anti-inflammatory omega-3 fatty acids. Plus, adding healthy fats to meals aids in the absorption of fat-soluble vitamins like A, D and E, which are crucial for immune health.[9]

Other key nutrients for stronger immunity include vitamin C, magnesium and selenium. It’s important to get a wide range of nutrients from a variety of whole plant foods to ensure a strong immune response against viruses and other pathogens.

Foods that Weaken the Immune System

Some foods hinder immune function, which can make you more susceptible to viral infections:

• Fried foods promote inflammation, which dampens overall immune response.
• Highly processed foods, including refined grains and sugars, deplete nutrients and prevent proper immune function.
• Meat may be a source of food-borne pathogens — including viruses — and toxic chemicals, both of which can interfere with your immune system. Many animal products have also been shown to increase inflammation.[10][11]

These foods also have a negative effect on gut health, which can have serious consequences for all body systems. The combination of pro-inflammatory compounds and low fiber content skews the balance of bacteria in the gut, leading to a weakened gut wall and increasing the risk for chronic inflammation. Plant foods, by contrast, promote beneficial gut bacteria and are generally anti-inflammatory.

Shifting your eating patterns away from processed and animal foods toward more whole, plant-based options is one powerful step you can take to give your body the tools it needs to fight off viruses. For optimal immune function, make sure you’re also getting enough good-quality sleep, following a regular exercise regimen, keeping stress levels in check and practicing good hygiene. The more you can do to cultivate an overall healthy lifestyle, the stronger your immune system will be.

References

1. Seladi-Schulman, Jill. “Viral Diseases: List of Types & Contagiousness, Treatment, Preven.” Healthline. March 29, 2019. https://www.healthline.com/health/viral-diseases.
2. “Rhinovirus and the Common Cold Fact Sheet.” Morgridge Institute for Research. https://morgridge.org/outreach/teaching-resources/virology-immunology/rhinovirus-and-the-common-cold-fact-sheet
3. “Disease Burden of Influenza.” Centers for Disease Control and Prevention. January 10, 2020. https://www.cdc.gov/flu/about/burde
4. “Viral Infection Types, Treatment, and Prevention.” OnHealth. July 01, 2016. https://www.onhealth.com/content/1/viral_infections.
5. “The Immune System.” Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/conditions-and-diseases/the-immune-system.
6. Kerley, Conor. “Can Nutrition Help Prevent Common Cold & Flu Viruses?” Center for Nutrition Studies. March 18, 2020. https://nutritionstudies.org/can-nutrition-help-prevent-common-cold-flu-viruses.
7. Mikulak, Joanna, Elena Bruni, Ferdinando Oriolo, Clara Di Vito, and Domenico Mavilio. “Hepatic Natural Killer Cells: Organ-Specific Sentinels of Liver Immune Homeostasis and Physiopathology.” Frontiers in Immunology 10 (2019). doi:10.3389/fimmu.2019.00946.
8. 4 Ways to Show Your Liver Some Love (Your Immune System Will Thank You!) – VitaVibes Blog.” Vitacost.com. December 04, 2016. https://www.vitacost.com/blog/vitamins-supplements/herbs/4-ways-to-show-your-liver-some-love-your-immune-system-will-thank-you.html.
9. Henson, Heidi. “Breathe Easy: Tips to Support Respiratory Health.” Center for Nutrition Studies. March 12, 2020. https://nutritionstudies.org/breathe-easy/.
10. Markantonis, Nikolas, Petra Vasickova, Monika Kubankova, Pavel Mikel, and George Botsaris. “Detection of Foodborne Viruses in Ready-to-eat Meat Products and Meat Processing Plants.” Journal of Food Safety 38, no. 2 (2018). doi:10.1111/jfs.12436.
11. Greger, Michael. “Poultry Exposure Tied to Liver & Pancreatic Cancer.” NutritionFacts.org. September 13, 2013. https://nutritionfacts.org/video/poultry-exposure-tied-to-liver-and-pancreatic-cancer/.

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Theresa “Sam” Houghton is a graduate of the Bauman College Nutrition Consultant program and the CNS and eCornell Plant-Based Nutrition Certificate. Through her wellness consulting business, GreenGut Wellness, she helps people achieve vibrant health with a whole food, plant-based diet.

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We began this archive as a means of assisting our visitors in answering many of their health and diet questions, and in encouraging them to take a pro-active part in their own health. We believe the articles and information contained herein are true, but are not presenting them as advice. We, personally, have found that a whole food vegan diet has helped our own health, and simply wish to share with others the things we have found. Each of us must make our own decisions, for it's our own body. If you have a health problem, see your own physician.