THE BABY BEAT – June 4, 2014
D. Gary Benfield, M.D.
Iodine deficiency in pregnancy, still worrisome after
all these years
Once upon a time, back in the 1920s, there was an area of the United States and
Canada known as the “goiter belt.” It was centered in Michigan and extended
throughout the Great Lakes region, the plains states and on up into Canada.
A goiter is an enlarged thyroid gland, which is often visible as a mass in the
upper neck. Back in the 1920s, before iodine was added to table salt, most goiters
were due to a lack of iodine in the soil. Since the body does not make iodine, it is
an essential part of our diet because iodine is required for the production of thyroid
hormones. And during pregnancy, adequate iodine intake is essential for fetal
thyroid function and normal brain development. Thus, iodine deficiency leads to
enlargement of the thyroid or goiter, hypothyroidism, and to mental retardation in
infants and children whose mothers are iodine deficient during pregnancy.
My wife, Cathy, was born and raised in Wisconsin. She recalls taking “goiter
pills” in the 1950s while in elementary school. They were chocolate-flavored
iodine pills that tasted pretty good. The reason for supplying children with this
added source of iodine was to prevent hypothyroidism and a resultant goiter from a
lack of iodine in their regular diet.
When iodine was added to table salt and potassium iodide was added to most
multivitamin pills, the experts thought the problem of iodine deficiency in the
goiter belt and throughout the United States was solved. No more iodine-deficient
THE BABY BEAT – June 4, 2014
Iodine deficiency in pregnancy, still worrisome after all these years
goiters, no more iodine deficient hypothyroidism, and, surely, no more newborns
suffering from congenital hypothyroidism due to maternal iodine deficiency.
But now comes the American Academy of Pediatrics (AAP) with a new
cautionary policy statement about iodine deficiency. Here are a few highlights:

Approximately one-third of pregnant women in the United States are
marginally iodine deficient, perhaps because the salt in processed foods does
not contain iodine. Note: I have a 26 oz container of Morton Salt in my
hand. It states the following: “This salt does not supply iodide, a necessary
nutrient.” I say shame on Morton Salt for not adding iodide to this product
and not doing its part to prevent iodine deficiency and all of its
consequences.

Iodine deficiency can interfere with normal brain development in their
offspring. Thus, pregnant and lactating women should take a supplement
containing adequate iodide. But only about 15 percent do so.

Such supplements, however, may not contain enough iodide and may not be
labeled accurately. This issue is currently under study by the FDA.
Okay, so how much supplemental iodide should pregnant and lactating women
consume? I take a multivitamin tablet daily that contains iodine as potassium
iodide. Each tablet contains 150 micrograms of potassium iodide.
The American Thyroid Association and the National Academy of Sciences
recommend that breastfeeding mothers consume 290 micrograms of iodide per
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THE BABY BEAT – June 4, 2014
Iodine deficiency in pregnancy, still worrisome after all these years
day, divided between a supplement with 150 micrograms of iodide and 140
micrograms from their diet.
In the United States, although most pregnant and lactating women take
supplements, only 15 percent to 20 percent take supplements that contain any
iodide. Many prenatal/lactation vitamins do not contain iodide, and those that do
contain iodide are often formulated to have 150 micrograms or less of potassium
iodide. In addition, there is wide variability in the measured iodide content of
supplements, regardless of what the label states.
In general, then, all pregnant and breastfeeding women should take a
multivitamin containing at least 150 micrograms of iodide per day.
A further thought: Congenital hypothyroidism due to iodine deficiency is the
most common preventable cause of mental retardation in the world. Even mild
iodine deficiency during pregnancy, which does occur in the United States, may be
associated with low intelligence in children.
© 2014 Gary Benfield
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