Thyroid hormones regulate metabolism, therefore body temperature and weight. The thyroid hormones contain iodine, which the thyroid needs in order to manufacture these hormones. If a person lacks iodine in his/her diet, the thyroid cannot make the hormones, causing a deficiency. In response to the body’s feedback loops calling for more thyroid hormones, the thyroid gland then enlarges to attempt to compensate (The body’s plan here is if it’s bigger it can make more, but that doesn’t help if there isn’t enough iodine.). This disorder is called goiter.
I have always been a seafood person and since I dont live on the cost I have to make sure I get enough tuna, lobster, and seaweed in my diet to avoid the above disorder called goiter. Once the government added iodine to our salts this has alleviated many problems.