Editor's Note: There's a good chance that many of your pregnant and breastfeeding patients aren't getting enough iodine, according to a policy statement published recently by the American Academy of Pediatrics (AAP).
How exactly should you counsel your patients? For advice, Medscape recently spoke with Heather L. Brumberg, MD, MPH, Associate Professor of Pediatrics and Clinical Public Health at New York Medical College, and a member of the AAP Council on Environmental Health.
Medscape: Why do clinicians need to be aware of this issue?
Dr. Brumberg: We know that iodine deficiency in the United States is occurring at least marginally in about one third of pregnant women. Also, this deficiency may be compounded by environmental exposures that are ubiquitous: for example, perchlorate, which may take the place of iodide and thus make iodide less available for the thyroid and for breastmilk.[3,4] Perchlorate uses the sodium-iodide symporter, which is what usually moves iodide or other anions into the thyroid follicular cells or human milk in the mammary gland. Perchlorate, an anion, competes with iodide for the symporter and thus inhibits uptake of iodide.[5,6]
Medscape: What does the AAP recommend?
Dr. Brumberg: Women should be taking adequate amounts of iodine, which range between 290 µg and 1100 µg per day; this could include a supplement of 150 µg of iodine. And 150 µg of iodine is equivalent to a supplement containing 197 µg of potassium iodide, because 76% of potassium iodide contains iodine, so there's a little conversion involved. This is higher than the recommendations for other adults because of the need for the increased amount of iodine for the infant or fetus.
Medscape: What are the effects of an iodine deficit?
Dr. Brumberg: It can result in inadequate production of thyroid hormone, which leads to hypothyroidism in the infant. We know that thyroid hormone is necessary for proper brain development. Therefore, infants and children are at risk for severe mental deficiencies, and even in milder cases of low thyroid, cognitive developmental issues may occur.
Medscape: Which health providers are you targeting with this message?
Dr. Brumberg: The message is targeted to pediatricians and any caregivers of pregnant women, women who intend to become pregnant, and breastfeeding moms -- and in theory, even internal medicine doctors. Many different providers come in contact with breastfeeding moms, pregnant women, or women who intend to become pregnant. It's important in preconception health counseling, too.
Medscape: How do you envision providers responding to these recommendations?
Dr. Brumberg: Caregivers of pregnant women, women of reproductive age who are intending to become pregnant, and breastfeeding moms should encourage the use of supplements with adequate amounts of iodine. Also, when patients are using salt, caregivers should encourage them to use iodized salt.
Breastfeeding moms should avoid excess nitrates, which can occur in well water, because it could interfere with the body's handling of iodine. As a corollary, the American Academy of Pediatrics recommend that all well water should be tested for nitrate levels annually to help prevent too high an exposure to nitrate.
Furthermore, tobacco smoke is a source of a compound called thiocyanate, which can compete with iodine. So, it's another reason not to smoke and to avoid secondhand smoke.
Caregivers and interested providers should support and advocate for the Environmental Protection Agency's regulation of perchlorate levels in water. And they can support and advocate for the US Food and Drug Administration's (FDA's) correction of the inconsistent and inadequate content of iodine in supplements and inaccurate labeling of such.
Medscape: How common is it for supplements to not be labeled accurately?
Dr. Brumberg: A 2009 study in the New England Journal of Medicine looked at the iodine content of prenatal multivitamins and found a lower content than what is actually needed by a pregnant woman or a lactating woman in many of the vitamins tested, as well as a discordance between what was labeled as the amount of iodine vs what was actually in the vitamin. In addition, 13 of the brands studied had levels of iodine that were discordant by 50% or more, and 10 of those brands had values that were lower by 50% or more.
Medscape: Are physicians not having these conversations with women?
Dr. Brumberg: I think a lot of the recommendations are not being done. Providers should be making the recommendations to avoid the environmental exposures -- the nitrates in well water and thiocyanate in smoke. In addition to being aware of the environmental exposures that may affect the uptake of iodine, it is important for providers to counsel women to be aware that supplements need adequate iodine content.
Medscape: Should these recommendations be a part of every consultation?
Dr. Brumberg: Absolutely, because they involve behaviors that could be easily changed. These aren't hard things to incorporate into your life: taking supplements, using iodized salt, making sure your well water is tested, and avoiding tobacco smoke.
Medscape: What trends in eating patterns may have led to this iodine deficit?
Dr. Brumberg: One reason for the deficiency in iodine is the increased consumption in the United States of processed foods; these don't contain, in general, iodized salt. The second contributor is that the supplements taken in pregnancy or by breastfeeding women, as we mentioned before, don't contain adequate amounts of iodine and are not always labeled correctly. Furthermore, environmental exposures, such as perchlorate, nitrate, and thiocyanate, may in fact increase the effects of iodide deficiency by competing with the iodide in the thyroid or mammary glands.
Medscape: Does any research show that these effects have been more pronounced since these eating patterns have emerged?
Dr. Brumberg: Iodine deficiency in the United States has been worsening. It used to be, with the introduction of iodized salt, that we really reduced or almost eliminated iodine deficiency. But it has increased starting from the 1970s to the 1990s. Recently, when National Health and Nutrition Examination Survey data on urine iodine content were examined, it was noted that deficiencies were pervasive. One third of pregnant women were found to be at least marginally iodine deficient.
Medscape: Could dietary modifications negate the need for supplements?
Dr. Brumberg: It would be difficult to get all of the necessary iodine through diet alone, especially because intake of seafood is encouraged, but in limited amounts during pregnancy. Dairy food, such as cow's milk or yogurt, could help, as well as iodized salt. However, iodine content is not always noted in all foods, making it even more challenging to accurately assess.
Therefore, it's probably safest to have a daily supplement containing adequate amounts of iodine. This would obviously not be an additional supplement besides the prenatal vitamin, but instead should be solely the prenatal vitamin, as long as it contains enough iodine. Even this is difficult, because few supplements contain adequate amounts of iodine and labeling issues persist. But the FDA is moving to correct this.
Medscape Ob/Gyn © 2014 WebMD, LLC
Cite this: Why You Should Talk to Your Pregnant and Nursing Patients About Iodine Supplements - Medscape - Aug 11, 2014.