Iodine in our food is dependant on the iodine found in the ground where the food is grown, in the food the animals receive, as it influences the iodine content in the meat and eggs we consume.
Iodine is used in the production of hormones (such as thyroxine, thyroxin) by the thyroid gland, which in turn regulates the conversion of fat to energy, stabilizing our body weight as well as controlling our cholesterol levels. These hormones produced from the iodine are also needed to help form our bones, as well as keeping our skin, nails, hair and teeth in prime condition. Some indication also exists that iodine is helpful in preventing cancer of the breast and womb.
Although too low levels of iodine can cause a goiter, so too can too high intake of iodine
Iodine is rapidly eliminated from the body, so high intake or toxicity is not very likely, but if your diet is supplement with too much kelp or iodine you could have problems with acne or skin rashes.
When iodine in the soil is very low, or if very little seafood is consumed a person may want to check their iodine intake, or when breast feeding or pregnant as well as being on a sea-salt restricted diet.