All About Zinc
What and Where is Zinc?
Zinc is the second most abundant trace metal in the human body after iron, and is a crucial element of protein structure and function. (1) The human body does not have specialised storage for zinc, so we must meet a daily requirement through diet or supplementation in order to maintain adequate levels. (2) Foods that provide good levels of zinc include oysters, red meat, poultry, beans, nuts, crab, lobster, whole grains, fortified breakfast cereals and dairy products. (3)
Globally, zinc deficiency is quite common, at around 17-20%, however the majority of these cases are in low socioeconomic countries. (1) Zinc deficiency is less common in high-income countries, though certain populations are more at risk, including the elderly, vegetarians/vegans, individuals with chronic disease, and children with ADHD. (1, 4) Futhermore, even though severe zinc deficiency is rare in places like Australia, mild deficiency is quite common. (5)
Zinc and the Immune System
Zinc plays an important role in cellular respiration, immune functions, protein synthesis, wound healing, DNA synthesis and cell division. (2) The immune system is especially responsive to alterations in zinc levels, with zinc homeostasis being tightly regulated both systematically and intracellularly. (1, 5) This strict regulation of zinc levels is indicative of the essential role that zinc plays in human health. (1)
A deficiency in zinc effects all aspects of the immune system and demonstrates that availability of zinc is crucial for the proper development and function of the immune system. (2) Zinc deficiency can lead to reduced numbers of T and B lymphocytes in both the thymus and the bone marrow, resulting in an escalated vulnerability to infection and a deterioration of the body’s defences. (5) In fact, alterations in zinc status have been associated with an increase in infectious diseases, cancer, chronic diseases (e.g. bronchial asthma), Alzheimer disease, and autoimmune diseases. (2)
Zinc has direct antiviral qualities (against, for e.g. influenza), but also plays an essential role in generating both innate and acquired antiviral responses, by contributing to their signalling pathways. (1)
The strongest effect that zinc exerts on the immune system is through Th1 and Th2 lymphocytes. With a reduced zinc level in the cell, the balance between Th1 and Th2 cells is disturbed. (5) This has an important impact on proper immune response because Th1 and Th2 lymphocytes perform different functions, that is, immunity against intracellular as opposed to extracellular pathogens. (5)
At therapeutic doses, zinc supplementation has the capacity to significantly improve the clearance of both chronic and acute viral infections, along with their associated pathologies and symptoms. (1) In clinical studies, zinc supplementation has been successfully used for rhinovirus infections, including a reduction of the duration of the common cold by up to 42%. (1)
The imbalance between Th1 and Th2 lymphocytes is eliminated with zinc supplementation due to it significantly increasing the release of IFN-γ (Interferon gamma) from the peripheral blood mononuclear cells. IFN-γ is the main Th1-inducing factor and has antiviral, immunoregulatory, and anti-cancer properties.
Zinc is an essential element for human health. Although severe zinc deficiency in places like Australia is rare, mild deficiencies are quite common, particularly in the elderly, vegetarians/vegans, children with ADHD, or people with chronic disease. Due to zinc’s importance in immune function, it is imperative that appropriate zinc levels are reached and maintained, and can be done so through dietary intake, or a good quality supplement.
1. Read SA, Obeid S, Ahlenstiel C, Ahlenstiel G. The Role of Zinc in Antiviral Immunity. Advances in nutrition (Bethesda, Md). 2019;10(4):696-710.
2. Bonaventura P, Benedetti G, Albarède F, Miossec P. Zinc and its role in immunity and inflammation. Autoimmunity reviews. 2015;14(4):277-85.
3. National Institutes of Health. Zinc Fact Sheet for Health Professionals [Internet]. 2020 [cited July 15 2020]. Available from: https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/#:~:text=Oysters%20contain%20more%20zinc%20per,products%20%5B2%2C11%5D.
4. Villagomez A, Ramtekkar U. Iron, Magnesium, Vitamin D, and Zinc Deficiencies in Children Presenting with Symptoms of Attention-Deficit/Hyperactivity Disorder. Children (Basel, Switzerland). 2014;1(3):261-79.
5. Skrajnowska D, Bobrowska-Korczak B. Role of Zinc in Immune System and Anti-Cancer Defense Mechanisms. Nutrients. 2019;11(10).
Written By Brittany Darling
NUTRITIONIST (BHSC), WESTERN HERBAL MEDICINE (ADV DIP),
CERT. PAEDIATRIC NUTRITION