Iodine
Overview
Iodine is something I have been aware
of since childhood. My mother always made sure she used iodized
salt, both for cooking and for table use. This is something that I
have been happy about, as both my first wife and now my second wife
have been conscious about having iodized salt for use. Iodine is
crucial in production of the thyroid hormone. Those of us living
away from the coastal areas need to use iodized salt because there
are few other ways to obtain iodine unless you are a heavy consumer
of seafood from the oceans.
Iodine is a trace mineral that the body
needs to make thyroid hormones, which are essential for normal growth
and development. In your body, about 70 - 80% of iodine is found in
the thyroid gland in the neck. The rest is distributed throughout the
body, particularly in the ovaries, muscles, and blood. If your body
doesn't have enough iodine, you can develop hypothyroidism (low
thyroid hormone levels).
Tests for iodine deficiency
A 24-hour urine iodine collection is a
useful medical test, as approximately 90% of ingested iodine is
excreted in the urine. If a 24-hour urine collection is not
practical, a random urine iodine-to-creatinine ratio can
alternatively be used. According to the World Health Organization
(WHO), in 2007, nearly 2 billion individuals had insufficient iodine
intake, a third being of school age. Thus iodine deficiency, as the
single greatest preventable cause of mental retardation, is an
important public-health problem. In the USA, it is important the
women bearing a child be tested and the newborn be tested as soon as
can reasonably done.
Recommended Daily Allowance
The Food and Nutrition Board at the
Institute of Medicine recommends the following dietary intake for
iodine:
Infants
0 - 6 months: 110 micrograms per day
(mcg/day)
7 - 12 months: 130 mcg/day
Children
1 - 3 years: 90 mcg/day
4 - 8 years: 90 mcg/day
9 - 13 years: 120 mcg/day
Adolescents and Adults
Males age 14 and older: 150 mcg/day
Females age 14 and older: 150 mcg/day
Specific recommendations depend on age,
gender, and other factors (such as pregnancy). Women who are pregnant
or producing breast milk (lactating) need higher amounts. Ask your
doctor for the amount that is best for you.
Function
Iodine is needed for the normal
metabolism of cells. Metabolism is the process of converting food
into energy. Humans need iodine for normal thyroid function, and for
the production of thyroid hormones. Iodine is a trace mineral and an
essential nutrient found naturally in the body.
Food Sources
Iodized salt -- table salt with iodine
added -- is the main food source of iodine. Seafood is naturally rich
in iodine. Cod, sea bass, and haddock are good sources. Kelp is the
most common vegetable seafood that is a rich source of iodine. Dairy
products also contain iodine. Other good sources are plants grown in
iodine-rich soil.
Precautions
Lack of enough iodine (deficiency) may
occur in places that have iodine-poor soil. Many months of iodine
deficiency in a person's diet may cause goiter or hypothyroidism.
Without enough iodine, the thyroid cells and the thyroid gland become
enlarged. No area maps for locations rich in iodine are currently
available; however, seacoast areas are generally the highest in
iodine.
Deficiency happens more often in women
than in men, and is more common in pregnant women and older children.
Getting enough iodine in the diet may prevent a form of physical and
mental retardation called cretinism. Cretinism is very rare in the
U.S. because iodine deficiency is generally not a problem.
Iodine poisoning is rare in the U.S.
Very high intake of iodine can reduce the function of the thyroid
gland.
Possible Interactions
If you are currently being treated with
any of the following medications, you should not take iodine until
you have first talked to your health care provider:
Antithyroid Drugs -- Use of
antithyroid drugs, including propylthiouracil (PTU), and iodide may
increase the hypothyroid effect of iodides.
Lithium -- Use of potassium
iodide and lithium (Lithobid) may cause hypothyroidism.
Warfarin -- Use of potassium
iodide (for hyperthyroidism) and warfarin (Coumadin, a blood thinning
drug) may make warfarin less effective.
High blood pressure medication (ACE
inhibitors and ARB's (Angiotensin Receptor Blockers)) -- Many
iodine supplements contain potassium. When used with ACE inhibitors
and ARB's, iodine may result in an increased level of potassium in
the body, which may be dangerous.
Potassium sparing diuretics --
Since many iodine supplements contain potassium, concurrent use may
result in dangerously high levels of potassium.
Amiodorone -- Concurrent use
with iodine supplements may result in dangerously high levels of
iodine.
Most people get plenty of iodine, and
because of the complex way iodine can affect the thyroid, you should
not take iodine supplements unless your doctor tells you to.
