Zinc and Immune Function David Randall, Fleet Surgeon
Vitamins and other supplementation remain popular topics. COVID has further kindled interest as people look to nutrients to enhance immune and overall health. This element is the second most common mineral in the human body behind iron. It is involved in at least 3,000 enzymes and 1,000 DNA and RNA transcription processes (1) Deficiency can cause cognitive impairment, reduced healing ability, immunity problems, and growth retardation. (1, 2) Under - developed countries see growth stunting below the age of 5. (3) Zinc’s anti-inflammatory benefits have long been recognized. (2) Low levels have association with allergy and auto immune processes (2). Zinc affects oxidative stress and inflammatory response; lack is probably involved in rheumatoid arthritis (RA), diabetes mellitus (DM), atherosclerosis, acute macular degeneration and cognitive function. (2, 4) Deficiency has association with chronic pediatric diarrhea in third – world countries. Supplementation has probably saved millions of lives due to this. (2) One study with older patients taking zinc showed a 21% - 25% reduction in acute macular degeneration; also, the group receiving it had a 27% reduction in overall mortality. (1) A study in under - developed areas similarly showed reduced all – cause mortality. (3). Deficiency affects many immune processes such as maturation of T and B cells, macrophages, natural killer cells, and regulatory T cells (important in autoimmune processes). (2) Seventeen to twenty percent of people worldwide have some level of deficiency and thirty percent in southeast Asia. (3, 2, 5, 6) Individuals at risk include those with cirrhosis of the liver, irritable bowel syndrome, and people aged 60 and older. (1, 2, 5) One study in elderly patients taking 45 mg of zinc showed a 66% reduction in all infections over a one – year period. (1) The body lacks the ability to store zinc, requiring regular intake. (6) Red meat and oysters provide good sources of this element. (2, 6) Surprisingly, foods with phytic acid (functions to binds phosphorus) such as grains, beans, tubers (carrots, potatoes, beets) reduce zinc absorption since they bind this as well, interfering with intestinal absorption. (2,6) Adult recommended daily allowances are 8 mg for women and 11 mg for men. (5) This, however, reflects a perfect – world scenario. The National Institutes for Health note that doses up to 40 mg daily are tolerated with a study underway of 50 mg. (7). Doses above 50 mg can cause gastrointestinal upset. (5) However, dividing the amount into twice – daily dosing generally corrects this.
Today’s big question asks whether this element has anti – infectious benefit, particularly with COVID. The short answer is most likely yes. Supplementation has been shown beneficial for
urinary tract infections, hepatitis, human immunodeficiency virus (HIV), bacterial / parasitic disease, DM, and RL. (2) Zinc interferes with replication cycles of Herpes Simples one and two. (5). It has been shown to have inhibitory benefit with Herpes Zoster virus (shingles), rhinovirus (common cold), polio, and hand – foot – and mouth disease (5) Zinc has been beneficial in both enhancing treatment of hepatitis C as well as reducing the likelihood of secondary development of liver cancer. (4) Similar b enefit has also been shown with severe acute respiratory syndrome (SARS), known for its outbreak in 2003. (5) One study found that oral zinc gluconate lozenges started within 24 hours of onset of the common cold reduced symptom duration 42% (4) Another showed a 32% reduction in mild to moderate and 87% reduction in moderate to severe respiratory tract infection symptoms. (2020 Hunter) Deficiencies of zinc, iron, and selenium levels correlate with severity of COVID – 19 symptoms. Research efforts to date have emphasized pharmaceutical treatments and further study is required. However, at this point it is to be realistically optimistic in the benefit of Zinc with regard to this disease. (4) And, finally, Jim Rich promises to by drinks for anyone who reads this article…. 1. Prasad AS. Discovery of human zinc deficiency: its impact on human health and disease. Adv Nutr. 2013 Mar 1;4(2):176-90. doi: 10.3945/an.112.003210. PMID: 23493534; PMCID: PMC3649098. 2. Wessels I, Maywald M, Rink L. Zinc as a Gatekeeper of Immune Function. Nutrients. 2017 Nov 25;9(12):1286. doi: 10.3390/nu9121286. PMID: 29186856; PMCID: PMC5748737. 3. Wessells KR, Brown KH. Estimating the global prevalence of zinc deficiency: results based on zinc availability in national food supplies and the prevalence of stunting. PLoS One. 2012;7(11):e50568. doi: 10.1371/journal.pone.0050568. Epub 2012 Nov 29. PMID: 23209782; PMCID: PMC3510072. 4. Li Y, Luo W, Liang B. Circulating trace elements status in COVID-19 disease: A meta- analysis. Front Nutr. 2022 Aug 12;9:982032. doi: 10.3389/fnut.2022.982032. PMID: 36034929; PMCID: PMC9411985. 5. Read SA, Obeid S, Ahlenstiel C, Ahlenstiel G. The Role of Zinc in Antiviral Immunity. Adv Nutr. 2019 Jul 1;10(4):696-710. doi: 10.1093/advances/nmz013. PMID: 31305906; PMCID: PMC6628855. 6. Maxfield L, Shukla S, Crane JS. Zinc Deficiency. [Updated 2022 Oct 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK493231/ 7. National Institutes of Health. Dietary Supplements in the Time of COVID – 19. https://ods.od.nih.gov/factsheets/DietarySupplementsInTheTimeOfCOVID19-Consumer/ 8. Hunter J, Arentz S, Goldenberg J, Yang G, Beardsley J, Myers SP, Mertz D, Leeder S. Zinc for the prevention or treatment of acute viral respiratory tract infections in adults: a rapid systematic review and meta-analysis of randomised controlled trials. BMJ Open. 2021 Nov 2;11(11):e047474. doi: 10.1136/bmjopen-2020-047474. PMID: 34728441; PMCID: PMC8578211.
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