i think i took a zinc suppliment for most of my younger years...like 4-17 or 18. I don't know exactly but i was on it for a long time. to be honest i don't know why i was on it but my peds cf doc thought it was a good idea and my parents/I trusted her completely so i took it. It also helps me when i'm getting a cold--i take those coldeeze lozenges now so maybe it helped me growing up because i never got all that many colds....just a thought