Part two of our series delving into popular “immune-boosting” supplements centers on Zinc. We’ll keep the preamble brief and jump right into the action. Let’s go!
What is Zinc?
Zinc is an essential trace mineral required for the activity of over 300 enzymes in the body. It is found in every organ, tissue, and fluid of the body.
Zinc also happens to be the second most abundant trace mineral in the body, behind iron. As you can surmise, Zinc plays a key role in numerous biological processes. [1,2]
It also supports a healthy immune response (more on that in a bit). But, first…
What Does Zinc Do?
As mentioned above, your body requires Zinc for the catalytic activity of hundreds of enzymes involved in the production and metabolism of carbohydrates, fats, proteins, and nucleic acids (building blocks of DNA and RNA). 
But that’s not all.
Zinc also plays a crucial role in:
- Cell Division
- Immune Function
- Thyroid Function
- Wound Healing
- Stabilizing Cell Structures
Benefits of Zinc
Supports Immune System Health
Zinc is required to activate lymphocytes (T cells), which help control and regulate immune responses as well as attack malignant cells. 
Deficiencies in Zinc can severely impair the proper functioning of the immune system.
Studies note that the elderly, as well as those individuals who are immunocompromised, may benefit from zinc supplementation as doing so may help improve lymphocyte production, natural killer cell activity, and resistance to infections. [9,10]
May Reduce Duration of Colds
Additional research indicates that supplementation with 9-24mg of Zinc (as zinc gluconate or zinc acetate) may help reduce the duration of symptoms of the common cold in adults. [7,8] It’s worth noting, though, that several studies have found no benefit from supplementing with Zinc. [13,14]
Researchers postulate that Zinc may help reduce the severity and duration of cold symptoms by directly inhibiting rhinovirus binding and replication in the nasal mucosa. And, Zinc may also be helping to suppress inflammation. [11,12]
A 2013 Cochrane review also stated that :
“Zinc administered within 24 hours of the onset of symptoms reduces the duration of common cold symptoms in healthy people, but some caution is needed due to the heterogeneity of the data. As the zinc lozenges formulation has been widely studied and there is a significant reduction in the duration of cold at a dose of ≥ 75 mg/day, for those considering using Zinc it would be best to use it at this dose throughout the cold.”
Zinc helps maintain the integrity of skin and mucosal membranes.
Research has noted a link between zinc deficiency and stunted wound healing. 
A pair of studies have found that zinc supplementation may accelerate the healing process after surgery or severe trauma. [16,17]
Asthma & Allergies
Some research indicates that low levels of Zinc may result in more severe asthma symptoms. 
Animal research notes that zinc supplementation may help decrease airway inflammation. [19,20]
Still, more human research is needed before it’s safe to say that zinc supplementation is an effective option for reducing asthma and allergy symptoms.
Additional Benefits of Zinc Supplementation
Other benefits attributed to zinc supplementation include:
- Reduce the Duration and Severity of Diarrhea
- Improved Memory and Learning
- Greater Skin Health
- Improved Mood
- Improved Blood Sugar Levels
- Increase Poor Appetite
Now, it must be stated that most of the positive outcomes resulting from zinc supplementation are the result of correcting a zinc deficiency.
What this means is that if an individual presently has a zinc deficiency, supplementation can help bring up his/her zinc levels to normal, and restore proper functioning of the immune system, wound healing, etc.
However, supplementing above and beyond the recommended intake of Zinc will not likely impart any additional benefits, and it may even be hazardous.
Excessive Intake of Zinc
Despite what you may have been led to believe, it is possible to have too much of a good thing.
Consuming more than 40mg per day of elemental Zinc has been known to cause flu-like symptoms, such as headache, fever, coughing, and fatigue. 
Other acute adverse effects of excessive zinc intake include :
- Loss of Appetite
Additionally, excessive zinc intake can also reduce copper absorption, alter iron function, decrease immune function, and reduce levels of high-density lipoproteins (“good” cholesterol). 
Best Sources of Zinc
A wide variety of foods contain Zinc, some may be more common to your diet than others.
Here is a list of foods rich in Zinc:
mg Zinc per 100g serving
% Daily Value
Beef (Chuck Steak)
Lean Pork Chops
Other significant sources of Zinc are nuts and seeds.
For instance, a 1-ounce serving (28 grams) contains 15% of the daily value of Zinc. And, a 30-gram serving of hemp seeds contains 31% of the daily value of Zinc.
It should be noted, though, that Zinc obtained from animal sources is more easily absorbed than that obtained from plant foods. This is because plant foods contain various compounds that reduce zinc absorption (such as phytate). 
Recommended Intake of Zinc
Currently, the recommended dietary allowance (RDA) for Zinc is:
- Women: 8 mg per day
- Men: 11 mg per day
Similar to water-soluble vitamins (B vitamins), the body does NOT store zinc long-term, making it necessary to intake daily. 
A deficiency in Zinc can lead to stunted growth, diarrhea, impotence, hair loss, eye, and skin lesions, impaired appetite, and depressed immunity.
Conversely, consuming too much Zinc can lead to nausea, vomiting, loss of appetite, abdominal cramps, diarrhea, and headaches in the short term. It can disrupt the absorption of copper and iron in the long term.
Zinc is an essential trace mineral involved in immune function, cell division, and numerous other biological processes.
Supplementing with 15–30 mg of Zinc daily may help boost immunity, blood sugar levels, and skin health. However, be sure not to exceed the recommended upper limit of 40 mg.
Consuming excessive Zinc can lead to headaches, flu-like symptoms, digestive issues, and decreased copper absorption.
Zinc is readily found in several foods common to the diet, including seafood, beef, dairy, nuts, seeds, and legumes.
Zinc supplements are widely available.
Steel Multi-V™ supplies 15mg Zinc per serving.
Steel Multi-V™ delivers more than 30 nutrients to help support the increased nutrient demands of physically active individuals, including essential vitamins and minerals as well as antioxidants and metabolism support agents.
- Kumar J, Barhydt T, Awasthi A, Lithgow GJ, Killilea DW, Kapahi P. Zinc Levels Modulate Lifespan through Multiple Longevity Pathways in Caenorhabditis elegans. PLoS One. 2016;11(4):e0153513. Published 2016 Apr 14. doi:10.1371/journal.pone.0153513
- John E, Laskow TC, Buchser WJ, et al. Zinc in innate and adaptive tumor immunity. J Transl Med. 2010;8:118. Published 2010 Nov 18. doi:10.1186/1479-5876-8-118
- Dhawan DK, Chadha VD. Zinc: a promising agent in dietary chemoprevention of cancer. Indian J Med Res. 2010;132(6):676–682.
- McCall, K. A., Huang, C., & Fierke, C. A. (2000). Function and mechanism of zinc metalloenzymes. The Journal of Nutrition, 130(5S Suppl), 1437S-46S. https://doi.org/10.1093/jn/130.5.1437S
- Hunt, J. R. (2003). Bioavailability of iron, Zinc, and other trace minerals from vegetarian diets. The American Journal of Clinical Nutrition, 78(3 Suppl), 633S-639S. https://doi.org/10.1093/ajcn/78.3.633S
- Kaltenberg, J., Plum, L. M., Ober-Blobaum, J. L., Honscheid, A., Rink, L., & Haase, H. (2010). Zinc signals promote IL-2-dependent proliferation of T cells. European Journal of Immunology, 40(5), 1496–1503. https://doi.org/10.1002/eji.200939574
- Hemilä H. Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. JRSM Open. 2017;8(5):2054270417694291. Published 2017 May 2. doi:10.1177/2054270417694291
- Singh, M., & Das, R. R. (2013). Zinc for the common cold. The Cochrane Database of Systematic Reviews, (6), CD001364. https://doi.org/10.1002/14651858.CD001364.pub4
- Barnett, J. B., Dao, M. C., Hamer, D. H., Kandel, R., Brandeis, G., Wu, D., … Meydani, S. N. (2016). Effect of zinc supplementation on serum zinc concentration and T cell proliferation in nursing home elderly: a randomized, double-blind, placebo-controlled trial. The American Journal of Clinical Nutrition, 103(3), 942–951. https://doi.org/10.3945/ajcn.115.115188
- Licastro, F., Chiricolo, M., Mocchegiani, E., Fabris, N., Zannoti, M., Beltrandi, E., … Masi, M. (1994). Oral zinc supplementation in Down’s syndrome subjects decreased infections and normalized some humoral and cellular immune parameters. Journal of Intellectual Disability Research : JIDR, 38 ( Pt 2), 149–162. https://doi.org/10.1111/j.1365-2788.1994.tb00370.x
- Hulisz D. Efficacy of Zinc against common cold viruses: an overview. J Am Pharm Assoc (2003) 2004;44:594-603.
- Caruso TJ, Prober CG, Gwaltney JM Jr. Treatment of naturally acquired common colds with Zinc: a structured review. Clin Infect Dis 2007;45:569-74.
- Turner RB, Cetnarowski WE. Effect of treatment with zinc gluconate or zinc acetate on experimental and natural colds. Clin Infect Dis 2000;31:1202-8.
- Eby GA, Halcomb WW. Ineffectiveness of zinc gluconate nasal spray and zinc orotate lozenges in common-cold treatment: a double-blind, placebo-controlled clinical trial. Altern Ther Health Med 2006;12:34-8
- Rojas, A. I., & Phillips, T. J. (1999). Patients with chronic leg ulcers show diminished levels of vitamins A and E, carotenes, and Zinc. Dermatologic Surgery : Official Publication for American Society for Dermatologic Surgery [et Al.], 25(8), 601–604. https://doi.org/10.1046/j.1524-4725.1999.99074.x
- Faure, H., Peyrin, J. C., Richard, M. J., & Favier, A. (1991). Parenteral supplementation with Zinc in surgical patients corrects postoperative serum-zinc drop. Biological Trace Element Research, 30(1), 37–45. https://doi.org/10.1007/bf02990340
- Al-Kaisy, A. A., Salih Sahib, A., & Al-Biati, H. A. H. K. (2006). Effect of zinc supplement in the prognosis of burn patients in iraq. Annals of Burns and Fire Disasters, 19(3), 115–122.
- Khanbabaee, G., Omidian, A., Imanzadeh, F., Adibeshgh, F., Ashayeripanah, M., & Rezaei, N. (2014). Serum level of Zinc in asthmatic patients: a case-control study. Allergologia et Immunopathologia, 42(1), 19–21. https://doi.org/10.1016/j.aller.2012.07.008
- Lang, C., Murgia, C., Leong, M., Tan, L.-W., Perozzi, G., Knight, D., … Zalewski, P. (2007). Anti-inflammatory effects of Zinc and alterations in zinc transporter mRNA in mouse models of allergic inflammation. American Journal of Physiology. Lung Cellular and Molecular Physiology, 292(2), L577-84. https://doi.org/10.1152/ajplung.00280.2006
- Morgan CI, Ledford JR, Zhou P, Page K. Zinc supplementation alters airway inflammation and airway hyperresponsiveness to a common allergen. J Inflamm (Lond). 2011;8:36. Published 2011 Dec 7. doi:10.1186/1476-9255-8-36
- Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2001.
- Hooper PL, Visconti L, Garry PJ, Johnson GE. Zinc lowers high-density lipoprotein-cholesterol levels. J Am Med Assoc 1980;244:1960-1.
- Chan, S., Gerson, B., & Subramaniam, S. (1998). The role of copper, molybdenum, selenium, and Zinc in nutrition and health. Clinics in Laboratory Medicine, 18(4), 673–685.