I think your thoughts on this theory may be correct. I have gone on the candida diet, took supplements, antifungals, and it just frustrated me to death with no results. I just tried eating almonds a few minutes ago (which also contain zinc) and definitely see an improvement since this morning. I have also started taking Pepsin HCL this morning as well so that may have also helped. My tongue had a very thick coat yesterday too! Today it's thinned out and cleared up a little. I'm thinking that my stomach acid is so low that it's not absorbing the nutrients I need which is causing me vitamin deficiency. I take multi-vitamins and when I pee, it is neon yellow. I've researched and when your pee in neon, it means your body isn't absorbing nutrients properly. But today after taking the HCL supplements, and having almonds in my system, my tongue looks significantly better than when I've been eating no sugar, carbs, etc. I definitely think you're on to something with the zinc and vitamin deficiency. Thanks for sharing! You may have saved me!:)