F. Lynn,
Thanks for posting the interesting article on zinc as a cold treatment.
One minor clarification:
The author, Atul Gawande, M.D, said:
The zinc trials did not, for example, mask zinc's bitter, medicine-like flavor. Zinc may work primarily because its distinctive taste helps convince you that it will.
The operative word is "may" so I have to disagree with your statement "He concludes any efficacy is due largely to a placebo effect"
I presume that you posted the article with Zicam in mind. Since Zicam is administered in the nose and has no aftertaste or side effects, I would be interested in how you think the placebo effect could affect its study results. I agree that Quigley's study results could have been affected by the placebo effect if they didn't mask the taste of zinc in the real lozenges or make the placebos taste like the real ones.
The following quotes from the article are interesting:
Some scientists question whether it is even biologically plausible that zinc could cure colds. Zinc backers propose that the element's positive charge could a) bind it to viruses, blocking their entry into the cells along your nasal tract or b) allow it to "clamp" nerves that stimulate congestion. However, University of Virginia researcher Jack Gwaltney pointed out that zinc in the saliva does not reach the nasal tract, and therefore cannot exert any of these effects.
This statement provides two reasons why zinc might be effective against the common cold. The reason that some researchers doubted its efficacy is that a sufficient concentration of zinc might not have reached the nasal tract. It doesn't appear from Dr. Gawande's article that anyone disputes whether zinc ions might bind to the cold virus and prevent their entry into the body. Other research that I have read on the Internet indicates that zinc ions might bind to cold viruses and block their entry into the body. I posted a list of links on this thread about a month ago. Zicam doesn't use saliva as a delivery system to the nasal tract and this could explain why it has been found to be effective. Zinc lozenges use the blood stream to reach the site of infection and the absorption rate could vary dramatically by individual. This could explain the erratic results of zinc lozenges.
Thanks,
Dan |
