Zinc is one of the few vitamin/mineral supplements I've found that has really made a difference in how I feel. I discovered it when a nutritionist, upon looking at the white spots on my fingernails, announced that I had a zinc deficiency. Apparently she was right. When I take zinc regularly, the spots go away. When I stop, they come back. It's nice to have such an obvious marker that something is working and not just clearing right out of your system.
The biggest difference zinc made for me was that I went from having six or eight colds a year to only having one or two, and sometimes not even that many. I also seem to feel better overall when taking it.
I take 100mg a day, which my doctor says is a lot. I'm able to keep colds away at half that amount, but unless I go up to 100mg, the spots on my fingernails don't clear up. I don't mind the spots, but if they're signs of a deficiency, I want to take enough to get rid of them.
My recommendation for anyone trying zinc for the first time is to check your fingernails first. If you don't have any indication of a deficiency, start small (zinc can be purchased in 30mg capsules), and pay close attention to how you feel. If you don't notice a dramatic difference, you probably don't need it. I think it's better not to take supplements your body doesn't need, since taking too much of something you don't need can cause imbalances in your internal chemistry.
I like Solaray Bio Zinc because the zinc comes in three different forms: Citrate, Picolinate, and Chelate. However, after taking Zinc for many years, I can't really say I've noticed much difference between brands and types.
*Creative Commons Photo by JeanPierreG.