Iodine helps make thyroid hormones, which help keep cells and the metabolic rate (the speed at which chemical reactions take place in the body) healthy. Good sources of iodine Good food sources of iodine include: sea fish shellfish Iodine can also be found in plant foods, such as cereals and grains, but the levels vary depending on the amount of iodine in the soil where the plants are grown. Adults need 140 micrograms (μg) of iodine a day. Most people should be able to get all the iodine they need by eating a varied and balanced diet. If you are following a strict vegan diet and do not eat any fish then you may want to consider taking an iodine supplement.