Is it safe to take thyroid complex supplements?

I am on a very strict diet and an worried about the amount of iodine I am taking in, I don't think its enough so I figure if I take supplements I can be sure not to get iodine deficiency, but I read that you can od on iodine if you have to much but I have no iodine in my current diet and I don't plan on changing my diet because apart from that it is a great diet and has nearly all essential vitamins and minerals. Also I heard enough iodine in the body increases your metabolism?