Seaweeds, fish, and shellfish are excellent sources. The richest sources from fish are cod, sea bass, perch and haddock. Kelp is particularly high in iodine. In the American diet, besides salt, the most common sources of iodine are in dairy and processed foods. Other sources of iodine can be onions, peanuts, lettuce, mushrooms, spinach, pineapple, green peppers, whole wheat bread and cheddar cheese.
Animals grazing on iodine rich soil can also be good sources of iodine.
Some foods called goitrogens, can actually interfere with the formation of thyroglobulin and therefore produce goiter. These sources include cabbage, peanuts, soybeans, millet and cauliflower. Drugs like sulfa medicines can also be goitrogens. Iodine is requisite for normal thyroid functioning which in turn regulates the metabolic energy of the body. The thyroid hormones set our BMR or basal metabolic rate.