Iodine

Forms:  Potassium iodide, iodized salt

Sources:  Kelp, iodized salt

RDA:  290 mcg for lactating mothers

Description:  Iodine is an essential component in the thyroid hormones triiodothyronine (T3), and thyroxin (T4).  These thyroid hormones in turn regulate growth and brain development, metabolism, and reproductive function.  An iodine deficiency can cause an underdeveloped brain along with mental retardation, and is a leading cause of avoidable brain damage.  In addition, a deficiency can cause goiter (thyroid gland enlargement) along with hypothyroidism which can sometimes be irreversible.  Some cruciferous vegetables such as broccoli, cauliflower, and cabbage can inhibit iodine uptake by the thyroid gland.  As a result, these vegetables can potentially increase the requirements for iodine.  The Tolerable Upper Level of intake is set at 1,100 mcg for adults and doses above that are not recommended.