My brother has actually thrown up from taking zinc lozenges on an empty stomach. Some people can do zinc away from food, however, the worst time to do it is before one has eaten anything for the day at all. If you take zinc on "too empty" of a stomach and get nauseous, eating something soon will often stop the nausea a lot sooner than it would have ended otherwise.
I haven't seen much on zinc toxicity from supplements either. Likely because generally athletes need a lot more zinc combined with the fact that bioavailability of zinc supplements is pretty darn low.
Justin, look into this article, particularly the parts on B6. http://www.acu-cell.com/acn.html