Function:
Iodine is an essential component of thyroid hormones which are involved in multiple enzyme processes and metabolism.

Recommended Dietary Allowance:
150 mcg a day for both men and women.

Deficiency:
Deficiency can cause simple goiter (enlargement of the thyroid gland). When the deficiency is severe there may be a deficit of thyroid hormones with dry skin, loss of hair, puffy face, weakness, weight gain and mental slowness. In infants mental retardation and dwarfism may also occur (cretinism). There are almost six million cretins in the world today.

Sources:
Prevention of iodine deficiency is most simply accomplished by regularly eating seafood or by using iodized table salt. Many cultures enjoy eating seaweed which is rich in iodine.

Toxicity and UL:
Excess iodine ironically can cause goiter. People with autoimmune thyroid disorders, nodular goiter or previous iodine deficiency may be particularly sensitive to iodine. It is not known in these individuals what the ideal daily amount is or if "normal" quantities may cause the thyroid to malfunction.

Cases of life threatening overdose do not occur with foods or supplements.

Adults should not consume more than the UL of 1.1 mg daily.

Recommendation:
Supplementation with iodine daily at the RDA is advisable if the diet is low in seafood, seaweed or iodized salt. In individuals with autoimmune thyroid disease, nodular goiter or previous iodine deficiency no supplement should be taken without a physicians advice.

For more information visit:
http://osu.orst.edu/dept/lpi/infocenter/minerals/iodine/index.html