Immune boosting has been a popular topic recently. Google trends show a steep increase in the search of the phrase “immune boost” and social media platforms, such as Instagram, show a 46% increase in the use of the hashtag #immunebooster in 2020 . Nutraceutical and dietary supplement sales experienced tremendous market growth in the last year as well . Hence, it is not surprising that scientists are conducting a plethora of new research to investigate the potential of bioactive compounds to enhance our immunity and prevent viral infections. While there is a lot of research focused on vitamin C and vitamin D, a few other nutraceuticals and micronutrients have generated a lot of interest, including Melatonin, Quercetin, Elderberry, Turmeric, and Zinc. This article will examine the studies around these micronutrients and nutraceuticals in an effort to understand why they have risen to prominence.
Melatonin is well known for helping with circadian rhythm and sleep issues. Less known, Melatonin has shown a lot of promise as an immunity boosting antiviral therapeutic due to its anti-inflammatory, antiapoptotic, immunomodulatory, and powerful antioxidant properties. As an anti-inflammatory, melatonin down-regulates pro-inflammatory cytokines, thereby alleviating symptoms. As an immunomodulator, melatonin improves immune response by increasing proliferation of T and B lymphocytes. A recent study  showed a 28% reduction in likelihood of a positive SARS-CoV-2 laboratory test in all combined populations when adjusting for age, sex, race and other comorbidities .
Another nutraceutical that has gained a lot of attention is Quercetin. Quercetin is a flavanol with wide spectrum antiviral properties, effective against both DNA viruses as well as RNA viruses by inhibiting replication . A few in vitro experiments have shown that Quercetin could inhibit the entry of some viruses by blocking the receptors on cells to which the viruses enter, and could possibly prevent certain infections. Further studies containing assays with the HIV-luc/SARS pseudotyped virus showed that Quercetin also had antiviral activity against these strains .
Quercetin is found in vegetables and fruits, especially Elderberry (Sambucus nigra). Elderberry is rich with flavonoids and anthocyanidins and has been used for ages as a diaphoretic for the treatment of common colds. Elderberry has immunomodulatory properties and its extract has shown in vitro antiviral effects against influenza viruses A and B. Elderberry extract has been found to reduce the duration and severity of colds due to its ability to reduce swelling in mucus membranes and block critical viral proteins that viruses need to enter and infect our cells .
One important micronutrient that quercetin works with to perform its immunomodulating function is Zinc . Zinc is required for proper functioning of enzymes, transcription factors, cellular signaling, and immune functioning. It is an anti-inflammatory agent and reduces the production of proinflammatory cytokines. In vitro studies have shown that Zinc does play a role in inhibiting RNA-dependent RNA polymerase in influenza, RSV, and in SARS-coronavirus family . In an article published in early May of this year, Johns Hopkins Medicine gastroenterologist Gerard Mullin, M.D. stated that Zinc has shown “to inhibit coronavirus RNA replication,” and when administered early, it can help “reduce the duration of symptoms from illness attributed to more innocuous coronavirus infections” .
Another flavonoid that has gained limelight is Curcumin, which is found in turmeric. It has been used in Ayurvedic and Chinese medicine for ages for its analgesic and anti-inflammatory properties. Recent research has highlighted its anti-cancer, antioxidant, and anti-microbial properties, especially as an antiviral compound, inhibiting replication in a wide-range of viruses . Studies have found that curcumin can reduce Human adenovirus early and late gene expression, as well as virus yield, in vitro. Therefore, curcumin nutraceuticals are being explored by researchers as broad-spectrum antiviral therapeutics.
Given all of the studies and trials with these micronutrients and nutraceuticals, it is clear why public interest in Melatonin, Quercetin, Elderberry, Turmeric, and Zinc is at an all-time high. However, healthcare experts advise us to exercise caution when using immune-boosting dietary supplements and to always check with our primary care physician before starting any supplements. In an interview with Health Matters, Dr. Ford, a primary care internist at New York-Presbyterian Medical Group Hudson Valley and an assistant professor of medicine at Weill Cornell Medicine said, “It’s one thing to eat elderberries, but it’s another thing to take a capsule that claims to be elderberry.” A related study conducted with 44 herbal supplements showed that 30 of them used filler ingredients and other product substitutions that contained allergens. Dr. Ford recommends focusing on consuming more whole-foods and a plant-based diet as that would provide the micronutrients our body needs. Dr. Ford asserts, “While there isn’t a magic pill to improve immune function, a healthy lifestyle as a whole is your best defense” .
Giovane, R. A., Giovanni-Kinsley, S. D., & Keeton, E. (2021, October 02). Micronutrients for potential therapeutic use against COVID-19; a review. Retrieved from https://www.sciencedirect.com/science/article/pii/S2405457721010809#bib14
Jennings, M. R., & Parks, R. J. (2020, October 31). Curcumin as an Antiviral Agent. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7693600/#B3-viruses-12-01242
Lordan, R. (2021, December). Dietary supplements and nutraceuticals market growth during the coronavirus pandemic - Implications for consumers and regulatory oversight. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8416287/
Mullin G.E., Limektkai B., Wang L., Hanaway P., Marks L., Giovannucci E. (2021) Dietary Supplements for COVID-19. In: Rezaei N. (eds) Coronavirus Disease - COVID-19. Advances in Experimental Medicine and Biology, vol 1318. Springer, Cham. https://doi.org/10.1007/978-3-030-63761-3_29
Skalny, A. V., Rink, L., Ajsuvakova, O. P., Aschner, M., Gritsenko, V. A., Alekseenko, S. I., . . . Tinkov, A. A. (2020, July 01). Zinc and respiratory tract infections: Perspectives for COVID‑19 (Review). Retrieved from https://doi.org/10.3892/ijmm.2020.4575
Tiralongo, E., Wee, S. S., & Lea, R. A. (2016, March 24). Elderberry Supplementation Reduces Cold Duration and Symptoms in Air-Travellers: A Randomized, Double-Blind Placebo-Controlled Clinical Trial. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4848651/
Wagner, D. N., Marcon, A. R., & Caulfield, T. (2020, September 03). "Immune Boosting" in the time of COVID: Selling immunity on Instagram. Retrieved from https://aacijournal.biomedcentral.com/articles/10.1186/s13223-020-00474-6
Wu W;Li R;Li X;He J;Jiang S;Liu S;Yang J;. (n.d.). Quercetin as an Antiviral Agent Inhibits Influenza A Virus (IAV) Entry. Retrieved from https://pubmed.ncbi.nlm.nih.gov/26712783/
Yi, L., Li, Z., Yuan, K., Qu, X., Chen, J., Wang, G., . . . Xiaojie Xu [email protected]College of Chemistry and Molecular Engineering, P. U. (2004, October 15). Small Molecules Blocking the Entry of Severe Acute Respiratory Syndrome Coronavirus into Host Cells. Retrieved from https://journals.asm.org/doi/10.1128/JVI.78.20.11334-11339.2004
Zakay-Rones, Zichria, et al. "Inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (Sambucus nigra L.) during an outbreak of influenza B Panama." The Journal of Alternative and Complementary Medicine 1.4 (1995): 361-369.
Zhou, Y., Hou, Y., Shen, J., Mehra, R., Kallianpur, A., Culver, D. A., . . . Cheng, F. (n.d.). A network medicine approach to investigation and population-based validation of disease manifestations and drug repurposing for COVID-19. Retrieved from https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000970&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+plosbiology/NewArticles+(PLOS+Biology+-+New+Articles)
Zimmerman (2021). “The Importance of Zinc and Quercetin During a Pandemic”. Retrieved September 2, 2021. https://www.healthfirstdc.com/blog/the-importance-of-zinc-and-quercetin-during-pandemic
7 Ways to Boost Your Immune System. (2021, August 18). How to Boost Your Immune System During a Pandemic. Retrieved from https://healthmatters.nyp.org/7-ways-to-boost-your-immune-system/