Iodine is an essential part of a hypothyroid diet.  The body needs extra iodine to make the thyroid hormones, even though it can produce this element naturally. As a result, we depend on foods and supplements to get the iodine we need.
Hypothyroidism is a condition marked by low thyroid hormone production. Therefore, consuming foods high in iodine can help improve the condition by encouraging the production of more thyroid hormones.
Common iodine-rich foods include milk, cheese, seaweed, saltwater fish, and whole eggs.  In many parts of the world, the most common source of iodine is iodized table salt. Not all table salts are iodized, so you should be mindful when buying salts.
Iodine deficiency can cause an enlargement of the thyroid gland known as goiter. It’s relatively uncommon to appear among people who are in areas with widespread use of iodized salt.
While consuming iodine-rich foods is good for you if you have an underactive thyroid, you should be careful not to overdo it. Too much iodine can cause an overproduction of thyroid hormones and result in another thyroid condition known as hyperthyroidism.
If you have a thyroid disorder, you should only supplement your diet with additional iodine if your doctor recommends it. Otherwise, basic iodine-rich foods are fine for hypothyroidism. No need to go overboard.