Immune health supplements are the most widely used supplements in the world. More than one-third of adults in the US and Europe take a daily multivitamin or other formula to support their health and reduce risk of disease.^[1]

However, a surprising proportion of “immune boosting” supplements on the market today are not backed by scientific evidence. A 2022 investigation into 30 supplements marketed to support the immune system revealed that more than half made misleading claims.^[2]

Your immune system is a complex network of cells, proteins, and organs that rely on a constant supply of certain nutrients. While no supplement can replace a wholesome diet, there are times when a quality product – with the right ingredients – can better support healthy immune system function by filling in nutritional gaps. It’s a matter of knowing what to look for – and how to separate fact from fiction.

Here are the nutrients that have been researched to support healthy immune function.

 

Probiotics

For a pathogen to cause an infection in the gut, it must bypass three key defenses: the gut microbiota, the intestinal lining, and the mucosal immune system.^[3]

Since 70-80% of immune cells are found in the gut, supporting gut health is key to immune function. Research shows that probiotics interact with the gut microbiome to enhance both innate and adaptive immune function. Lactobacillus and Bifidobacterium can help stimulate white blood cells (lymphocytes and macrophages) and regulate immune signals (cytokines and chemokines).^[4]

Certain probiotics play a role in strengthening the intestinal barrier, reducing opportunities for harmful microbes to invade. Some Lactobacillus species (casei, acidophilus, rhamnosus, plantarum, lactis) have been shown to boost IgA (one of the five primary immunoglobulins) and increase interleukin-6, a protein that enhances antibody production.^[5],[6]

 

Vitamin D

Vitamin D is involved in protecting against infections and autoimmune conditions. Among its many other roles,  immune system function by promoting antimicrobial peptides and nitric oxide synthase, which help fight bacteria, viruses, and fungi.^[7] It also supports adaptive immunity by mobilising T helper 2 cells to combat pathogens, and increases the numbers and activity of T regulatory cells (Tregs).  ^[8] Vitamin D increases production of anti-inflammatory substances, which can reduce susceptibility to infection.^[9]

 

Zinc

Zinc affects multiple aspects of the immune system, from skin barrier function to gene regulation in immune cells. Zinc facilitates communication between immune cells, influences inflammatory responses and antibody production, and supports the development of lymphocytes.^[10] It’s also essential for immune cell production and activation. Low levels of zinc are a common factor in weakened immune response.^[11]

Zinc is key to the integrity of the intestinal epithelium, and has been shown to shorten the duration and severity of acute and chronic diarrhoea by 15–24%.^[12] It also supports respiratory health, reducing the incidence of acute lower respiratory infections in children by 45% and even helping to shorten the common cold.^[13],[14]

 

Vitamin C

Vitamin C is widely recognised for its immune benefits. While it may not prevent the common cold, it can significantly shorten its duration.^[15]

Decades of research show that one of the many ways vitamin C supports immune defences is by enhancing neutrophil function: helping white blood cells respond more effectively to infection. Supplementation can increase neutrophil activity by 20%, which can contribute to faster recovery.^[16]

Vitamin C has also been shown to significantly increase levels of the antibodies IgA, IgG, and IgM, which protect the body against infection.^[17] It also acts as an important antioxidant to immune cells, protecting them from oxidative damage during an immune response.^[18]

 

Omega-3 fatty acids

Although not often cited as an immune supplement, omega-3 influences both innate and adaptive immune cells by supporting membrane structure and function and acting as signalling molecules.^[19] DHA and EPA (the most-studied omega-3 fatty acids) help to downregulate the production and secretion of pro-inflammatory cytokines, counteracting inflammation.^[20] These fatty acids also support the function of white blood cells (including macrophages) by improving their ability to remove harmful invaders, and encouraging a healing response that resolves inflammation and supports overall immune resilience.^[21]

 

Research matters

It’s easy to be swayed by label claims, but ingredients really do matter. If you feel your immune system could use a boost, choose a product with clinically researched ingredients.

Remember also that supplements are only one part of the picture. Even the most powerful ingredients are only effective when used to complement other healthy habits: a nutritious diet, adequate sleep, and regular exercise.

 

This information is provided for educational purposes only and is not a substitute for professional medical advice. Always seek the guidance of your physician or qualified healthcare provider with any questions you may have regarding your health or a medical condition.

 

References

^[1] Djaoudene, O., Romano, A., Bradai, Y. D., Zebiri, F., Ouchene, A., Yousfi, Y., Amrane-Abider, M., Sahraoui-Remini, Y., & Madani, K. (2023). A Global Overview of Dietary Supplements: Regulation, Market Trends, Usage during the COVID-19 Pandemic, and Health Effects. Nutrients, 15(15), 3320. https://doi.org/10.3390/nu15153320

^[2] Crawford, C., Avula, B., Lindsey, A. T., Walter, A., Katragunta, K., Khan, I. A., & Deuster, P. A. (2022). Analysis of Select Dietary Supplement Products Marketed to Support or Boost the Immune System. JAMA network open, 5(8), e2226040. https://doi.org/10.1001/jamanetworkopen.2022.26040

^[3] Iacob, S., Iacob, D. G., & Luminos, L. M. (2019). Intestinal Microbiota as a Host Defense Mechanism to Infectious Threats. Frontiers in microbiology, 9, 3328. https://doi.org/10.3389/fmicb.2018.03328

^[4] Raheem, A., Liang, L., Zhang, G., & Cui, S. (2021). Modulatory Effects of Probiotics During Pathogenic Infections With Emphasis on Immune Regulation. Frontiers in immunology, 12, 616713. https://doi.org/10.3389/fimmu.2021.616713

^[5] Mazziotta, C., Tognon, M., Martini, F., Torreggiani, E., & Rotondo, J. C. (2023). Probiotics Mechanism of Action on Immune Cells and Beneficial Effects on Human Health. Cells, 12(1), 184. https://doi.org/10.3390/cells12010184

^[6] Vitiñi, E., Alvarez, S., Medina, M., Medici, M., de Budeguer, M. V., & Perdigón, G. (2000). Gut mucosal immunostimulation by lactic acid bacteria. Biocell : official journal of the Sociedades Latinoamericanas de Microscopia Electronica … et. al, 24(3), 223–232.

^[7] Gallo, R. L., Murakami, M., Ohtake, T., & Zaiou, M. (2002). Biology and clinical relevance of naturally occurring antimicrobial peptides. The Journal of allergy and clinical immunology, 110(6), 823–831. https://doi.org/10.1067/mai.2002.129801

^[8] Prietl, B., Pilz, S., Wolf, M., Tomaschitz, A., Obermayer-Pietsch, B., Graninger, W., & Pieber, T. R. (2010). Vitamin D supplementation and regulatory T cells in apparently healthy subjects: vitamin D treatment for autoimmune diseases?. The Israel Medical Association journal : IMAJ, 12(3), 136–139.

^[9] Kearns, M. D., Alvarez, J. A., Seidel, N., & Tangpricha, V. (2015). Impact of vitamin D on infectious disease. The American journal of the medical sciences, 349(3), 245–262. https://doi.org/10.1097/MAJ.0000000000000360

^[10] Wessels, I., Maywald, M., & Rink, L. (2017). Zinc as a Gatekeeper of Immune Function. Nutrients, 9(12), 1286. https://doi.org/10.3390/nu9121286

^[11] Shankar, A. H., & Prasad, A. S. (1998). Zinc and immune function: the biological basis of altered resistance to infection. The American journal of clinical nutrition, 68(2 Suppl), 447S–463S. https://doi.org/10.1093/ajcn/68.2.447S

^[12] Bhutta, Z. A., Bird, S. M., Black, R. E., Brown, K. H., Gardner, J. M., Hidayat, A., Khatun, F., Martorell, R., Ninh, N. X., Penny, M. E., Rosado, J. L., Roy, S. K., Ruel, M., Sazawal, S., & Shankar, A. (2000). Therapeutic effects of oral zinc in acute and persistent diarrhea in children in developing countries: pooled analysis of randomized controlled trials. The American journal of clinical nutrition, 72(6), 1516–1522. https://doi.org/10.1093/ajcn/72.6.1516

^[13] Sazawal, S., Black, R. E., Jalla, S., Mazumdar, S., Sinha, A., & Bhan, M. K. (1998). Zinc supplementation reduces the incidence of acute lower respiratory infections in infants and preschool children: a double-blind, controlled trial. Pediatrics, 102(1 Pt 1), 1–5. https://doi.org/10.1542/peds.102.1.1

^[14] Godfrey, J. C., Godfrey, N. J., & Novick, S. G. (1996). Zinc for treating the common cold: review of all clinical trials since 1984. Alternative therapies in health and medicine, 2(6), 63–72.

^[15] Bucher, A., & White, N. (2016). Vitamin C in the Prevention and Treatment of the Common Cold. American journal of lifestyle medicine, 10(3), 181–183. https://doi.org/10.1177/1559827616629092

^[16] Bozonet, S. M., Carr, A. C., Pullar, J. M., & Vissers, M. C. (2015). Enhanced human neutrophil vitamin C status, chemotaxis and oxidant generation following dietary supplementation with vitamin C-rich SunGold kiwifruit. Nutrients, 7(4), 2574–2588. https://doi.org/10.3390/nu7042574

^[17] Prinz, W., Bortz, R., Bregin, B., & Hersch, M. (1977). The effect of ascorbic acid supplementation on some parameters of the human immunological defence system. International journal for vitamin and nutrition research. Internationale Zeitschrift fur Vitamin- und Ernahrungsforschung. Journal international de vitaminologie et de nutrition, 47(3), 248–257.

^[18] Wintergerst, E. S., Maggini, S., & Hornig, D. H. (2006). Immune-enhancing role of vitamin C and zinc and effect on clinical conditions. Annals of nutrition & metabolism, 50(2), 85–94. https://doi.org/10.1159/000090495

^[19] Gutiérrez, S., Svahn, S. L., & Johansson, M. E. (2019). Effects of Omega-3 Fatty Acids on Immune Cells. International journal of molecular sciences, 20(20), 5028. https://doi.org/10.3390/ijms20205028

^[20] Iverson, C., Bacong, A., Liu, S. et al. Omega-3-carboxylic acids provide efficacious anti-inflammatory activity in models of crystal-mediated inflammation. Sci Rep 8, 1217 (2018). https://doi.org/10.1038/s41598-018-19252-x

^[21] Chang, H. Y., Lee, H. N., Kim, W., & Surh, Y. J. (2015). Docosahexaenoic acid induces M2 macrophage polarization through peroxisome proliferator-activated receptor γ activation. Life sciences, 120, 39–47. https://doi.org/10.1016/j.lfs.2014.10.014