If you don't want to risk supplementing with minerals, which can be tricky because more is definitely NOT better, then try increasing eating more foods which contain zinc:

oysters and certain other fish
meats (beef has the highest, I think, grass fed if you can get it)
pumpkin seeds (squash seeds too, but not many folks eat those)

there are others but these are the main ones....

We started taking a mineral complex last night, it's the one by Source Naturals, called Life Minerals...it claims it is closest to the Krebs cycle and has high bioactivity. We won't take one every day, probably every other day or maybe even just 2 times a week, to see how we do. I'll share what we experience, good or bad.