Does trial evidence of Zicam cold remedy show that it is effective?

Are,

Have you tried the National Institute of Health? MedlinePlus Herbs and Supplements: Zinc

Another one of my favorites (albiet they are mostly just abstracts) is Entrez Pub Med

PubMed Home

I tried to search the FDA, but the site has changed drastically since my medical research days, and I am kind of studying right now. LOL

But I'll keep looking. This is rather interesting.

I don't know about Zicam but I will try to answer your question about zinc in general.
I hope I remember my reply that just got lost in cyberspace.
Zinc is good for colds/flus but most supplements are best when used with others that will optimize each other. Example, echineachea, vitamin C, E and goldenseal are all good for colds and flus and these optimize each other. You should not take echineachea or goldenseal long term. Also echineachea and goldenseal should be taken two weeks on two weeks off until you are better. My mother swears by it but often what works for one person might not work for another. I guess it has something to do with resistance.
You can over do zinc and should not take more than the rda.
I am not sure why they say zinc may decrease your ability to smell.
It may be the fact that it is sprayed directly in your nose.
A lost sense of smell and taste usually means a zinc deficiency.
From what I looked up to answer your question is that the Jury is still out on nasal zinc.
Often those studies are not worth anything because often they want a biased outcome against the supplement so they use poor quality not containing active ingredient, do not optimize and so forth. They did that with
Saw Palmento they didn't use one that had the active ingredient Beta Sito Sterol.
I lost all the links I had when the question disappeared for the minute or I would include them
This is an over all zinc that explains dosages and so forth.

Zinc information page. All about zinc and the role it plays in your diet.

The reply they sent you looks like a standard form letter companies have stacks of and send out when they don't want to be bothered.

I don't know about medical testings, but I used Zicam a year ago when in desperate straights!

It was opening night of 70 Girls, 70, I was Fritzi, had solos and tapdances and bucus of lines... And felt the dreaded cold coming on. Took Zicam and it went away and I had a successful Opening Night!

I just checked the search results for Zicam at the Consumer Reports website and it now does show results.

What I've already tried is the Zinc supplement of Dr. Mercola, and all I can say is I never been sick for almost a year now.