Zinc Intakes and Health Outcomes: An Umbrella Review

Abstract

It is widely accepted that the zinc element is crucial in human beings. Zinc has gained more attention during the COVID-19 pandemic due to its utilization for the treatment and prevention of respiratory tract infections. However, some studies also pointed out that zinc intake might cause unwanted side effects and even be dangerous when overdosed. To reveal the relationship between zinc intake and health outcomes, we performed an umbrella review from human studies. In total, the umbrella review included 43 articles and identified 11 outcomes for dietary zinc intake and 86 outcomes for supplementary zinc intake. Dietary zinc intake in the highest dose would decrease the risk of overall and specific digestive tract cancers, depression, and type 2 diabetes mellitus (T2DM) in adults. Supplementary zinc consumption in adults was linked to an improvement of depression, antioxidant capacity and sperm quality, higher serum zinc concentration, and lower concentration of inflammatory markers. Zinc supplementation in children would reduce the incidence of diarrhea and pneumonia, improve zinc deficiency and boost growth. However, zinc might not decrease all-cause mortality in adults or the in-hospital mortality of COVID-19. And better maternal and neonatal outcomes may not derive from pregnant women who consumed higher or lower doses of zinc supplementation (>20 mg/day and <20 mg/day, respectively). Dose-response analyses revealed that a daily 5 mg increment of zinc would lower the risk of colorectal and esophageal cancer, whereas a large dose of zinc supplementation (daily 100 mg) showed no benefit in reducing prostate cancer risk.

Development of Therapeutic and Prophylactic Zinc Compositions for Use against COVID-19: A Glimpse of the Trends, Inventions, and Patents

“…Zinc, a brittle and silver/grey metal in its unoxidized form, is represented by the symbol Zn (atomic number 30); it is the second most abundant metal in the human body, after iron [ 21 ]. Zinc is an essential nutrient because it is needed in almost all aspects of cellular/biological processes (i.e., catalytic functions, structural functions, and regulatory functions) of the human body [ 22 ]. The catalytic functions of zinc are attributed to its antioxidative nature, and to it being an essential component of ~3000 catalytic enzymes (e.g., dismutase, dehydrogenase, anhydrase, carboxypeptidase, aminopeptidase, lyase, metalloproteinase, S-methyltransferase, carboxytransferase, deacylase, hydrolase, nuclease, synthase, etc.)…”

“…The catalytic functions of zinc are attributed to its antioxidative nature, and to it being an essential component of ~3000 catalytic enzymes (e.g., dismutase, dehydrogenase, anhydrase, carboxypeptidase, aminopeptidase, lyase, metalloproteinase, S-methyltransferase, carboxytransferase, deacylase, hydrolase, nuclease, synthase, etc.) [ 22 , 23 ]. The structural functions of zinc include maintenance and stabilization of the intracellular components/cell membranes [ 22 , 23 ].…”

“…[ 22 , 23 ]. The structural functions of zinc include maintenance and stabilization of the intracellular components/cell membranes [ 22 , 23 ]. The regulatory functions of zinc encompass being a component of DNA/RNA polymerase, many kinases, and ribonuclease [ 22 , 23 ].…”

“…Accordingly, zinc should be consumed regularly in the diet—especially through foods of animal origin (e.g., meat, shellfish, etc. )—or as a supplement/medicine in order to prevent its deficiency [ 22 , 23 , 24 ]. The absorption of zinc increases in a diet containing protein, histidine, methionine, and citrate.…”

“…Zinc demonstrates its anti-inflammatory effect by suppressing the NF-κB signaling and attenuating the cytokine storm [ 30 , 31 ] ( Figure 2 ). Zinc also stimulates the generation of interferons that help in the synthesis of antiviral proteins (i.e., latent ribonuclease and protein kinase) that degrade the RNA of SARS-CoV-2 [ 22 ]. Zinc increases the activity of natural killer cells, cytotoxic cells, and B-cell receptor signaling, and increases the production of antibodies.…”