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Zinc Supplements and COVID-19

A video with Dr. Joshua Ritchie, Dean of the Refuah Institute in Israel, recommending dietary supplementation with zinc to protect against COVID-19 is zooming around the Internet. The question, is to what extent science should apply the brakes?

As a young physician, in 1968, Dr. Ritchie was part of a group that demonstrated the benefits of vitamin E supplementation in preventing anemia in formula-fed premature babies. After that, he does not appear to have published any research. His practice today is focussed on “life-coaching,” marriage, and youth counseling. In the video in question, he claims that he has carried out research on zinc supplementation and advises taking 30-40 mg of zinc a day as a weapon against infection by COVID-19. There is no evidence of any publication of his research.

Ritchie is certainly not the first to make a connection between infectious diseases and zinc. There have been numerous studies demonstrating that zinc2+ has antiviral effects, likely by up-regulating interferon-alpha production. Zinc also has anti-inflammatory activity through modulation of regulatory T cell function that may limit the “cytokine storm” associated with COVID-19. As a possible further benefit, zinc has anti-bacterial properties and may prevent bacterial co-infection when it comes to viral diseases. Some experiments have also shown that zinc inhibits RNA polymerase, an enzyme that coronaviruses need in order to multiply.

But, and a very big BUT, because all these effects have been shown “in vitro,” that is, in the lab. There are no human clinical trials that have demonstrated the benefit of zinc supplements in the prevention or treatment of COVID-19. While zinc deficiency is documented in the developing world, it is unlikely to be significant in the west since the recommended daily allowance for adults of about 10 mg is easily met given that the mineral is present in meat, grains, dairy, nuts, and beans. Vegetarians may have more difficulty in meeting requirements.

In summary, there is no doubt that zinc is required for the proper functioning of the immune system, but there is no evidence that people who become infected with SARS-CoV-2 have low levels and there are no studies that have shown an improvement in patients with zinc supplements. However, up to 40 mg of zinc in supplement form is recognized as being safe, so the advice given in the circulating video is not harmful, and may possibly be of benefit for some people. However, it should be appreciated that this recommendation is based on theory rather than on clinical evidence. Until there is a proper peer-reviewed publication on the effects of zinc supplementation in cases of COVID-19, any claims of benefit should be regarded as mere opinion.


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