Iodine is an essential chemical element for the production of thyroid hormones that help regulate growth and metabolism. Natural iodine exists in all living plants and animals. Food that comes from the sea contain the most iodine and the seaweed is an excellent source. In irony to this, salt from the sea, or salt from any other sources for that matter, does not contain iodine. Processed salt likeÊiodized salt is the only salt product that contain iodine because extra iodine is added during processing.