After some blood work my doctor has put me on Vitamin D and Iron. Two days after taking both I was experienceing bad anxiety. I did not make the connection at first and took them both for several more days experiencing even more anxiety. ( I was a nervous wreck) I stopped taking them and the anxiety went away. I thought the anxiety was from the Vitamin D because I was on a very high dose, and I took iron years ago and did not experience this type or recation. I consulted with a dietician and he feels that the iron was casuing the anxiety not the vitamin D. I do plan on trying the Vitamin D by itself to see how I feel. I wish I had more information on this subject for you. Good luck!