Iodine
Other name(s):
iodide, organic iodine, potassium iodide, sodium iodide
General description
In 1922, experts learned that the thyroid gland needs iodine. The gland needs it to
make thyroid hormones and prevent enlarged thyroid glands (goiter). Thyroid hormones
control metabolism. They also affect reproductive processes, nerves, muscles, skin,
and hair. Iodine also helps with the synthesis of protein and utilization of oxygen.
Iodine is in two main hormones made by the thyroid gland. Together, these hormones
control the metabolic rate of the body. They’re important in growth and development,
especially in the fetus and newborn. Not having enough iodine and thyroid hormones
can cause intellectual issues and developmental delays.
Medically valid uses
Iodine is used to prevent and treat goiters and over-active thyroid gland (hyperthyroidism).
It’s also used to prevent and treat iodine deficiency and thyrotoxic crisis.
Consuming table salt fortified with potassium iodide can help prevent goiters. Other
sources of iodine include eggs, dairy products, and seaweed.
If you get goiter during pregnancy, you’ll need treatment. This can keep your baby
healthy.
Unsubstantiated claims
Please note that this section reports on claims that have not yet been substantiated
through studies.
Iodine is said to reduce the risk of breast cancer, decrease fatigue, and stave off
weight gain. It may also help treat hardening of the arteries (arteriosclerosis).
Recommended intake
People living in the Great Lakes states need iodine supplements. This area is even
called the "goiter belt". People living in other areas without enough iodine in the
soil also need supplements. Before iodine was added to table salt, it’s thought that
50–70% of people living in the Lake Michigan area had goiters.
Adults who don’t get enough iodine in their diet can get goiters. In severe cases,
this may lead to an underactive thyroid gland (hypothyroidism). Symptoms can include:
People who consume large amounts of "goitrogenic" vegetables also need more iodine.
These include cabbage, kale, Brussels sprouts, and rutabagas. These substances keep
the digestive tract from absorbing iodine. Cooking deactivates goitrogenic substances.
Newborns that didn’t get enough iodine during pregnancy are often born with enlarged
thyroids. They may also have signs of hypothyroidism. If a fetus’s thyroid doesn’t
work during development, he or she can get cretinism. These problems can lead to intellectual
issues. They can also cause growth problems.
Iodine is measured in micrograms. The Recommended Dietary Allowance (RDA) is as follows:
|
Group
|
RDA
|
|
Infants (0 to 6 months)
|
110 mcg*
|
|
Infants (7 months to 1 year)
|
130 mcg*
|
|
Children (1–3 years)
|
90 mcg
|
|
Children (4–8 years)
|
90 mcg
|
|
Children (9–13 years)
|
120 mcg
|
|
Males (14 years and older)
|
150 mcg
|
|
Females (14 years and older)
|
150 mcg
|
|
Pregnant women
|
220 mcg
|
|
Breastfeeding women
|
290 mcg
|
*Adequate Intake (AI)
|
Food source
|
Nutrient content per 100 grams
|
|
Seaweed
|
61,990 mcg*
|
|
Iodized salt
|
10,000 mcg
|
|
Cod liver oil
|
838 mcg
|
|
Seafood, fish (depending on type of fish)
|
36–311 mcg
|
|
Seafood, shellfish (depending on type of shellfish)
|
31–129 mcg
|
|
Sea salt
|
94 mcg
|
Side effects, toxicity, and interactions
Elemental iodine is poisonous. This type is found in "tincture of iodine". It’s used
to disinfect cuts. Ingesting even a small amount can cause death.
Taking in too much iodine may cause a goiter. It may also keep your thyroid from working
well. This is more likely if you take doses close to 1,000 mcg per day.
Women who are pregnant or breastfeeding shouldn’t take iodine supplements without
talking to their healthcare providers. Too much iodine during pregnancy may cause
hypothyroidism and a goiter in a newborn.
People who take lithium shouldn’t take iodine supplements. Using these two substances
together can cause hypothyroidism. You also shouldn’t take iodine supplements if you’re
taking amiodarone.
Additional information
Many areas of the country have very little iodine in the soil. As a result, crops
in these areas and animals raised on these crops are exposed to little iodine. Before
iodine was added to table salt, many people in these areas had goiters. This problem
has mostly gone away now. This is likely due to iodized salt and the widespread consumption
of ocean fish and shellfish.
Iodized salt contains potassium iodide. It’s often in a ratio of one part iodine to
10,000–100,000 parts salt. This means there’s very little iodine in the salt. But
it’s enough to prevent goiter. Iodized salt made in the U.S. contains 76–100 mcg of
iodine per gram of salt.