Zincs connection to the common cold isnt as wooie as you all might be thinking after this weeks Zicamscepade (cough, sniffle). Though Zicam was marketed as a ‘homeopathic’ remedy, zinc–>common cold connection wasnt established by some naked sweaty white guy pretending he is a Native American deciding that Ayurvedic law dictates ‘colds’ require a ‘hot’ metal like zinc to neutralize viral chi.
Zinc–>common cold was discovered by boring ‘science’ a long time ago. In 1974, Korant et al tested a ton of metals ions at lots of different concentrations to see if they had any effect on cold virus replication– cadmium, calcium, cobalt, copper, magnesium, manganese, mercury, molybdenum, nickle, and zinc.
Zinc is the only one that worked. Turns out it interferes with the cleavage of an essential polyprotein (like how HIV-1 gp160 gets cleaved into gp120 and gp41), interfering with cold virus replication. YAY!
Well, all those experiments were in tissue culture. Know how we kill HIV-1 in tissue culture? Bleach. Tissue culture victories arent always real-world victories.
In 1984, a clinical trial involving zinc salt lozenges showed promise, but later analyses demonstrated that zinc salts did not provide therapeutic concentrations of zinc, so if zinc was ‘working’, it wasnt by the mechanism proposed in 1974.
Around 2000, scientists started publishing the results of their new idea: Maybe the zinc ions are binding to the receptors on the outside of the viruses, preventing them from binding to our receptors, limiting infection? Well, the cold virus replicates in your nose/respiratory tract, so why not just put zinc gel/spray up your nose? Like putting EGCG in condoms, put the drug where the action is.
Some of the nose-zinc trials worked, some didnt– the scientific community was still working out the kinks… too late. Zicam blew through the door in 1999, and was marketed straight to the public. None of that hoity-toity lab learnin for THEM!
Charles Hensley and his colleagues at Gel Tech thought the solution was as plain as, well, the nose on your face. Why not skip the mouth and spritz the zinc directly into the old proboscis? They developed a gel that can do just that and tried it out on 104 volunteers. The results of this study, having been withdrawn once, will probably never be published in a scientific journal. Because Zicam is marketed as a homeopathic remedy, however, the Food and Drug Administration doesn’t require it to undergo rigorous testing.
At this point, the only fair thing to say about Zicam is that its benefits are still not proved. Maybe if I’m desperate, I’ll try it next time I get a telltale tickle in my throat. In the meantime, I hope to sidestep the problem by following the advice of Dr. Jack Gwaltney of the University of Virginia School of Medicine, a top cold researcher. “Wash your hands a lot with soap and water,” he says, because cold viruses like to linger there. Don’t put your fingers in your eyes or nose, as they give easy access to the nasal passages.
Results: Coronal sections of the rat ONe and corresponding olfactory bulbs showed consistent cellular and tissue damage of increasing severity that correlated with the duration of treatment with the zinc compound when compared with the control group animals.
Conclusion: The results of this analysis indicate that the repeated oral administration of such zinc-containing compounds have neurotoxic effects on the ONe and to the mitral cells in the olfactory bulbs of treated rats. These findings point toward the need for increased investigation into the potential deleterious effects of zinc-containing compounds to humans as well.
Aaaaand here we are in 2009.
The agency says that since 1999, it has received more than 130 reports of loss of smell associated with Zicam Cold Remedy Nasal Gel; Zicam Cold Remedy Nasal Swabs; and Zicam Cold Remedy Swabs, kids size. The products have been linked to long-lasting or permanent loss of smell called anosmia. In some cases, the loss of smell occurred after the first dose.
So there you have it. The rise and fall of zinc as a cure for the common cold. Decades of work by real scientists has been tarnished in an instant by some money grubbing ‘homeopathic’ businessmen. Zinc didnt deserve to die like this.