Table 2.

Some problems (and queries) about using zinc in crisis medicine

∙ Recommended daily intake (RDI) for zinc is 12–15 mg taken orally. For crisis medicine, 200 mg/day has been used in tandem with other anti-infective agents (hydroxychloroquine, ivermectin, etc.)

∙ Estimated efficiency of intestinal zinc absorption from normal diets may be as low as 20%. This inefficiency is due to inhibition of zinc uptake by a) anti-nutrients,e.g., phytic acid, other polyphosphates, even phosphoric acid (added to soft drinks); b) copper or iron (II) competing with zinc for uptake by intestinal ABC transporters and c) metal chelators added to processed foods to prevent copper- or iron-induced rancidity, e.g., EDTA; unfortunately also complexing zinc (‘collateral damage’)

∙ There is little information about zinc bio-availability when using such ‘super-doses’

∙ For how long can they be used without overtaxing zinc detoxicant/excretion mechanisms or inducing profound copper deficiency?

∙ Does surplus unabsorbed zinc from such super-doses compromise the symbiotic commensal ‘good’ bacteria in the bowel?

∙ What is the effect upon normal zinc-storage mechanisms in bone, or natural sequestration by metallothioneins in the liver?

∙ Doses with > 150 mg/day oral zinc supplements can be toxic (Chandra 1984; Mindell 1985; Vaughan and Judd 2003;). Lower doses (25–40 mg/day) are therefore advocated (Razzaqe 2020) to reduce potential suppression of beneficial immune responses

∙ For further discussions of zinc and its importance for human health (for human health treating viral infections), see reviews by Chesapis et al. 2012, Read et al. 2019; Derwand and Scholz 2020; Razzaqe 2020; Skalny et al. 2020; Whitehouse 2020b, amongst others