Iodine
Other name(s):
iodide, organic iodine, potassium iodide, sodium iodide
General description
Iodine is an essential mineral element. It is naturally found in some foods, and added
to other foods. It can also be taken as a supplement. 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 functions, nerves, muscles, skin, and hair. Iodine also helps make protein
and use 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 an unborn baby and a 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:
Using table salt that has potassium iodide can help prevent goiters. Other sources
of iodine include eggs, dairy foods, and seaweed.
If you get goiter during pregnancy, you’ll need treatment. This can keep your baby
healthy.
Unsubstantiated claims
There may be benefits that have not yet been proven through research.
Iodine may help immune response. It may also have a helpful effect on mammary dysplasia
and fibrocystic breast disease.
Recommended intake
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 not exposed to much iodine. Before
iodine was added to table salt, many people in these areas had goiter. The Lake Michigan
area was once called the “goiter belt.” This problem has mostly gone away now. This
is likely because of iodized salt and the widespread consumption of ocean fish and
shellfish.
But people living in areas without enough iodine in the soil may still need iodine
supplements. This includes people living in the Great Lakes states and mountain regions
of the U.S. and Mexico.
Adults who don’t get enough iodine in their diet can get goiter. In severe cases,
this may lead to an underactive thyroid gland (hypothyroidism). Symptoms can include:
People who consume large amounts of soy, cassava, or uncooked cruciferous vegetables
also need more iodine. These include cabbage, cauliflower, broccoli, kale, Brussels
sprouts, and rutabagas. These foods have substances that keep the digestive tract
from absorbing iodine. Cooking stops the action of these substances.
Newborn babies who don't get enough iodine in the womb are often born with enlarged
thyroid glands. They may also have signs of hypothyroidism. If a baby's thyroid doesn’t
work during growth in the uterus, they can get congenital hypothyroidism. This can
lead to intellectual issues. It can also cause growth problems.
Iodine is measured in micrograms (mcg). 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 to 3 years)
|
90 mcg
|
|
Children (4 to 8 years)
|
90 mcg
|
|
Children (9 to 13 years)
|
120 mcg
|
|
Males (14 years and older)
|
150 mcg
|
|
Females (14 years and older)
|
150 mcg
|
|
Pregnant people
|
220 mcg
|
|
Breastfeeding people
|
290 mcg
|
*Adequate Intake (AI)
|
Food source
|
Nutrient content
|
|
Seaweed, dried, 2 tablespoons
|
116 mcg
|
|
Iodized table salt, ¼ teaspoon
|
76 mcg
|
|
Egg, hard boiled, 1 large
|
26 mcg
|
|
Cheese, cheddar, 1 ounce
|
15 mcg
|
|
Sea salt, non-iodized, ¼ teaspoon
|
<1 mcg
|
Iodized salt contains potassium iodide. It’s often in a ratio of 1 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 mcg to 100
mcg of iodine per gram of salt.
Side effects, toxicity, and interactions
Elemental iodine is toxic. This type is found in tincture of iodine. It’s used to
disinfect cuts. Swallowing even a small amount can cause death.
Getting too much iodine may also cause problems. It can also cause 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.
People who are pregnant or breastfeeding shouldn’t take iodine supplements without
talking to their healthcare providers. Too much iodine in pregnancy may cause hypothyroidism
and a goiter in a newborn.
Talk with your healthcare provider before taking iodine if you take any of these medicines: