This question doesn't duplicate the more limited one on Zicam; I ask here about zinc in general.

No: Mayo Clinic (from which I quote below) and WebMD are skeptical.

Since then, research has turned up mixed results about zinc and colds

Possibly yes: See NHS (from which I quote below) and The Telegraph .

For many years, it has been suggested that zinc supplements could relieve the symptoms of the common cold, but there was little clarity until a 2011 evidence review. This recent review suggested a modest reduction in the length of symptoms, although the results were not entirely conclusive. In a bid to help clarify the matter, researchers have conducted another review of evidence on this issue.

  • 1
    Why isn't this a duplicate of skeptics.stackexchange.com/questions/243/…?
    – Oddthinking
    Commented Dec 23, 2014 at 6:42
  • @Oddthinking That question doesn't appear to discuss zinc's effects on illnesses?
    – user16959
    Commented Dec 23, 2014 at 9:10
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    The sources you provide say basically the same thing, there's no controversy and the claim that "zinc may help" is backed by a systematic review with specific caveats. These results are clearly explained e.g. in the NHS article.
    – Sklivvz
    Commented Dec 23, 2014 at 11:36
  • @EbenezerSklivvze Thanks, but I seek a definitive, unequivocal answer? The model verb 'may' implies doubt or subjectivity?
    – user16959
    Commented Dec 23, 2014 at 14:28
  • The site is for challenging notable claims: what notable claim are you challenging? There is no claim that there is a unequivocal answer
    – Sklivvz
    Commented Dec 23, 2014 at 14:53