General Description
Iodine is a nonmetallic mineral essential in human nutrition. The
highest concentrations of iodine in the human body are found in
the thyroid gland, muscles, and endocrine tissues. Iodine functions
as a primary component of thyroxin and triiodotyrosine, thyroid
hormones that regulate growth, development, energy metabolism, and
body temperature. Supplemental forms of iodine include inorganic
iodides (iodine bonded to sodium or potassium) and organic sources
such as kelp and iodine casseinate.
Food sources
Iodine is found primarily in seafoods, including seaweeds. It
can also be found in foods grown on iodine-rich soil. In most
developed countries, the primary source of dietary iodine is iodized
salt, which generally provides 70 micrograms of iodine per gram
of salt.
Health applications
- Goiter
- Prenatal nutrition
- Hypothyroidism
Deficiency symptoms
Because iodine is an essential component of thyroid hormones,
deficiencies of the mineral cause thyroid disorders such as hypothyroidism
and goiter.
Iodine deficiency during pregnancy increases the risk of stillbirth
and infant mortality1 and can impair fetal
development, causing cretinism,
mental retardation, and other neurological abnormalities.2,3
In school-aged children, iodine deficiency has been linked to
retarded growth, hearing impairment, low I.Q., and poor psychomotor
development.4-6 While iodine deficiencies
are rare in the U.S. and other places where iodized salt is used,
they remain common in areas with low soil iodine levels where
iodized salt is not yet readily available. Because vegetarian
diets are associated with an increased risk for iodine deficiency,7,8
vegetarians (and especially vegans) should be sure to include
iodine-rich plants (such as kelp and other seaweeds) in their
diets, or use iodized salt.
Dosage/toxicity
The Reference Daily Intake (RDI) for iodine is 150 micrograms
per day. With the prevalence of iodized salt, most people can
easily get this amount in their regular diet. Iodine toxicity
is rare, seen primarily in people consuming large quantities of
seaweed9 and in those with excessive exposure
to iodine-containing chemicals. Excessive iodine intake has been
associated with inflammation of the thyroid, thyroid enlargement,
abnormal heart beat, heart failure, and an increased risk for
Graves' disease.10-12 |
