ACE2 and COVID-19: A previous study showed that the expression of angiotensin-converting enzyme 2 (ACE2) regulates the signaling of reactive oxygen species and NF-κB in a human lung cell line; zinc supplementation enhances the inhibitory effect and not only destroys the balance of the immune response but also affects the expression of ACE2 receptors, which are necessary for penetration into target cells for ACE2-associated diseases such as COVID-19 and should be considered for treatment.