Sea salt does have trace amounts of iodine, but it's not a good source of it. Iodine is also added to some table salts during processing, and occurs naturally in many foods. The recommended daily allowance for iodine is 150 micrograms and while most people easily meet or surpass this amount, individuals living in areas where this essential nutrient is lacking in soil and food may benefit from the iodine in sea salt.
In some parts of the world, iodine deficiency is due to a lack of this important mineral in soil. This deficiency leads to goiter, which is characterized by an enlarged thyroid gland. To avoid such conditions, experts recommend that individuals with low iodine levels take an iodine supplement, increase their intake of iodine-rich foods and use the iodine in iodized salt or sea salt as a food seasoning.
The amount of iodine in sea salt will vary, since it is not highly concentrated in this source. Studies suggest that a person with a low iodine level may not get enough of the mineral from sea salt alone to supplement her or his dietary needs. Iodized salt, however, tends to have higher levels of iodine in it than regular sea salt does. When ordinary table salt is originally processed, it is stripped of most of the natural minerals it contains. Before the process is completed, however, iodine is added to table salt, which may cause it to actually contain more of the mineral than sea salt does. Iodized sea salt, which has also been processed with added iodine, may also contain higher levels than plain sea salt.
Whether the mineral is gained via the iodine in sea salt or iodized salt, it is an extremely important part of the diet. Aside from low iodine causing goiter, it may also lead to hypothyroidism, which is a decline in thyroid hormone production. When this occurs, a person may experience such symptoms as elevated cholesterol, unintended weight gain, depression, pain throughout the body, leg swelling and constipation. Low iodine may also lead to intellectual deficiencies in children.
Neither the levels of iodine in sea salt nor the levels of the mineral present in iodized table salt are enough to be considered a complete iodine supplement. In order to maintain proper levels of the mineral, other foods high in iodine must also be consumed. Eating foods like certain dairy products, seafood and kelp may also help naturally increase iodine levels. These foods are only effective, however, if harvested from iodine-rich soil or sea water. Most people in the developed world can consume enough iodine simply by eating a balanced diet.