Nutrition to Improve Immune System Health

Individuals with immunodeficiency disorders are either born with them (primary) or have acquired them in time, usually later in life (secondary).1–3 According to researchers and physicians at Penn Medicine, when the defenses of the immune system are low or weak, this can negatively impact the body’s ability to combat disease or infection, making the individual more susceptible to harmful pathogens, infections, and diseases.3 Elements of the immune system that are typically affected are B cells (antibodies), T cells (pinpoints the pathogen’s antigen), combination B and T cells, phagocytes (harmful bacteria absorption), and the complement system (which is responsible for enhancing antibodies and phagocytic cells to clear an infection).1–4 

Many factors and conditions can weaken an individual’s immune response, which can be a temporary or permanent condition. Viral infections (e.g., influenza), cuts and burns, and mild inflammation can temporarily compromise the immune system.1–4 Certain infectious diseases, such as human immunodeficiency virus (HIV), viral hepatitis, and acquired immune deficiency syndrome (AIDS), are more permeant forms of immunodeficiency and tend to continuously destroy immune cells and create obstacles to fighting off bacterial and viral attacks. Additionally, some autoimmune diseases, like Type 1 diabetes, asthma, lupus, leukemia, and lymphoma, destroy immune cells and hinder the immune response. Chemotherapy, radiation, and other medical treatments, such as long-term use of corticosteroids, biologics, and disease-modifying antirheumatic drugs, can also compromise the immune system.1–4 A family history of immunodeficiency disorders, older age, and smoking are supplementary factors that either increase one’s risk of developing a compromised immune system or developing conditions that weaken the body’s immune response.1 Frequent, long-lasting infections, organ inflammation, blood disorders, digestive issues, slowed development and growth, and autoimmune disorders are commonly associated with being immunocompromised or having an immunodeficiency disorder.1

Below are some nutrition suggestions for supporting your immune system functioning and perhaps mitigating some associated symptoms that accompany immunodeficiencies. 


Berries contain polyphenolic plant compounds with anti-inflammatory and immune-boosting properties. Anthocyanin, a plant compound that provides berries with their vibrant red, purple, or blue pigments, is most notable for its anti-inflammatory and immune-boosting benefits.

Aim to integrate more blueberries, raspberries, cranberries, blackberries, and strawberries into your dietary lifestyle. Add berries to your morning cereal, afternoon smoothie, and evening dinner salad.


A member of the onion family, garlic is known to amplify protective cell immunity, like the natural killer cells that rid the body of other cells that have been affected by cancer and viruses, without disturbing healthy cells. Garlic also reduces inflammation. The raw form of garlic is the most nutrient dense, so consuming it in this form is the best way to reap garlic’s immune-boosting benefits.

Add chopped, raw garlic to salsa, pesto, and salad dressings.


The value of root vegetables lies within their antioxidant properties, which improve immune system responses and protect cell and tissue integrity. This is especially beneficial for managing the fall and winter prevalence of inflammation. The beloved sweet potato is loaded with antioxidants.


Vitamin E is a strong, lipidsoluble antioxidant that is found in immune cells, which regulate immune function and reduce risk of infection and inflammation. Most dark, leafy greens, such as raw swiss chard, steamed kale, raw spinach, and cooked beet greens, are full of vitamin E.


In terms of supporting the immune system, vitamin C remains the hardest-working nutrient, assisting in the production of antibodies. Did you know that one small orange contains 85 percent of the daily recommended amount of vitamin C?


Along with antimicrobial and antioxidant properties, the beta-glucan fiber found in oats has been shown to improve the immune system and reduce inflammation. Oats also contain protein, which can assist in elevating energy levels and combating excessive fatigue.

Additional Tips18

Individuals with immunodeficiency disorders are more susceptible to infections and sickness, so it is critical that their food and beverages remain clear of potentially harmful pathogens when preparing their meals, especially in patients undergoing chemotherapy. Wash hands, utensils, and any surfaces before food preparation; use different cutting boards for each type of food; scrub raw fruits and vegetables before cooking; and soak berries, other fruits, and vegetables in water and rinse before eating. To prevent bacteria growth in frozen or already cooked food, place any leftovers in the fridge right away; soak frozen fruits and vegetables that aren’t going to be cooked (e.g., for use in smoothies) in water; and thaw any frozen food in the fridge instead of letting it get to room temperature.

Overall, individuals with compromised immune systems should aim to reduce or eliminate their intake of salt, added sugars, saturated fats, animal products, and excess alcohol. They should not consume foods or drinks past the expiration dates, with signs of mold, or that have been left out for more than two hours. Avoid raw foods (seafood, sushi), deshelled nuts and seeds, bulk food bins at grocery stores, buffets, salad bars, and self-serve restaurants.


1.   Mayo Clinic staff. Primary immunodeficiency. Accessed 14 Jun 2021.

 2. National Institutes of Allergies and Infectious Diseases site. Types of primary immune deficiency diseases. Updated 13 Sept 2019. Accessed 14 Jun 2021.

3.  Penn Medicine site. What you need to know about being immunocompromised during COVID-19. 13 May 2020. Accessed 14 Jun 2021.

4.  Centers for Disease Control and Prevention site. General information for immunocompromised persons. Updated 8 Feb 2021. Accessed 14 Jun 2021.

5.  Cassidy A, Rogers G, Peterson JJ, et al. Higher dietary anthocyanin and flavonol intakes are associated with anti-inflammatory effects in a population of US adults. Am J Clin Nutr. 2015 Jul;102(1):172–181.

6.  Joseph SV, Edirisinghe I, Burton-Freeman BM. Berries: anti-inflammatory effects in humans. J Agric Food Chem. 2014;62(18):3886–3903.

7.  Panche AN, Diwan AD, Chandra SR. Flavonoids: an overview. J Nutr Sci. 2016;5:e47.

8.  Oregon State University: Linus Pauling Institute site. Flavonoids. Accessed 14 Jan 2021.

9.  Nantz MP, Rowe CA, Muller CE, 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.

10. Harvard T.H. Chan School of Health site. Sweet Potatoes. Accessed 14 Jun 2021.

11. Shortsleeve C. Are Sweet Potatoes Healthy? 10 Jan 2019. Accessed 14 Jun 2021.

12. United States Department of Agriculture site. Sweet Potato. 1 Apr 2019. Accessed 14 Jun 2021.

13. Pyo Y, Lee T, Logendra L, Rosen RT. Antioxidant activity and phenolic compounds of Swiss chard (Beta vulgaris subspecies cycla) extracts. Food chem. 2004;85: 19–26.

14. Lewis ED, Meydani SN, and Wu D. Regulatory role of vitamin E in the immune system and inflammation. IUBMB Journals. 2019(71);487–494

15. Carr AC and Maggini S. Vitamin C and Immune Function. Nutrients. 2017 Nov 3;9(11). pii: E1211.

16. The Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, (DC): The National Academy Press; 2000: 186–192.

17. Academy of Nutrition and Dietetics site. 5 whole grains to keep your family healthy. 27 Aug 2018.  Accessed 14 Jun 2021.

18. National Cancer Institute site. Eating hints: before, during, and after cancer treatment. (NIH Publication No. 18-7157.) NCI Office of Communications and Public Liaison;2019:1–41.   

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