Could dosing up on zinc help stave off severe illness from COVID-19? It's a question garnering closer attention in the scientific community in recent months. After all, zinc is known for its antiviral effects. And both the common cold and the current global pandemic are caused by viruses in the same family, known as coronaviruses. So could zinc be one of the keys to supporting the immune system and thwarting damaging inflammation caused by this new scourge?
There's no definitive answer to that question. But preliminary research released at an online European coronavirus conference this week hints at a possible link between lower blood levels of zinc and poorer health outcomes in people with COVID-19.
Dr. Roberto Guerri-Fernandez of Spain led the retrospective study, which looked at symptomatic people admitted to a Barcelona hospital from mid-March through the end of April. Fasting blood levels of zinc were taken from all 611 men and women (63 years old, on average) admitted to the COVID-19 unit during the study period. Researchers also had access to other lab results and patient data, including pre-existing conditions.
For the current analysis, the team focused on a representative sample of just 249 patients, including 21 who died. Zinc levels of those 249 people were 61 micrograms per deciliter, on average, when they were admitted to the hospital. But when researchers compared survivors' zinc levels to those who succumbed to the disease, they found a significant difference: 63.1 versus 43 micrograms per deciliter, on average. After adjusting for variables like age, sex, and severity, each unit increase in blood levels of zinc at the time of their admission was associated with a 7% lower risk of dying in the hospital.
"Lower zinc levels at admission correlate with higher inflammation in the course of infection and poorer outcome," the study authors noted.
While the study ties lower zinc levels at admission to increased risk of death in patients with COVID-19, it does not prove that one causes the other. It merely shows an association between the nutrient and the disease, Philip C. Calder, PhD, who was not involved in the study, tells Health. Calder is a professor of nutritional immunology and head of human development and health at the University of Southampton in the UK.
Before you start stocking up on zinc, keep several points in mind. First, the study is limited to a small group of patients at one hospital. The authors acknowledge that further research is necessary to assess any possible therapeutic effect. The findings, presented at the European Society of Clinical Microbiology and Infectious Diseases' online coronavirus disease conference, have yet to be published in a peer-reviewed medical journal; they're considered preliminary findings at this point.
Leo Anthony Celi, MD, principal research scientist at the Massachusetts Institute of Technology in Cambridge, Massachusetts, says there are "countless examples where fixing some abnormal finding does not change the outcome of a disease." In other words, we don't really know whether "fixing" blood levels of zinc would have any effect whatsoever on how COVID patients fare. Plus, he tells Health: "There may be other factors apart from age, sex, and illness severity that may confound the relationship between serum [blood] zinc levels and outcomes from COVID-19."
Zinc has some specific anti-viral actions, Calder notes. It acts to support the immune system and control inflammation, "therefore these findings could make sense," he says. He also noted that similar data have been published for selenium and vitamin D. Bottom line: People should try to make sure that they get enough of these nutrients in their diet or, if they're worried, they can take a multi-nutrient supplement, says Calder.
Actual zinc deficiency is uncommon in North America, according to National Institutes of Health Office of Dietary Supplements. When it does occur, it's usually due to inadequate intake or absorption of the mineral-and in those cases, eating food rich in zinc, such as oysters, red meat, beans, and nuts, or taking a supplement might make sense. Consult your doctor first.
Doing something, like taking a supplement, to reduce our susceptibility to COVID-19 has a certain allure, Dr. Celi concedes. But should you count on zinc to protect you and your loved ones? "Based on what we know at present," he says, "nothing beats the use of masks and the avoidance of crowds."
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