Iodine Deficiency, Pollutant Chemicals, and the Thyroid: New Information on an Old Problem

Abstract

Many women of reproductive age in the United States are marginally iodine deficient, perhaps because the salt in processed foods is not iodized. Iodine deficiency, per se, can interfere with normal brain development in their offspring; in addition, it increases vulnerability to the effects of certain environmental pollutants, such as nitrate, thiocyanate, and perchlorate. Although pregnant and lactating women should take a supplement containing adequate iodide, only about 15% do so. Such supplements, however, may not contain enough iodide and may not be labeled accurately. The American Thyroid Association recommends that pregnant and lactating women take a supplement with adequate iodide. The American Academy of Pediatrics recommends that pregnant and lactating women also avoid exposure to excess nitrate, which would usually occur from contaminated well water, and thiocyanate, which is in cigarette smoke. Perchlorate is currently a candidate for regulation as a water pollutant. The Environmental Protection Agency should proceed with appropriate regulation, and the Food and Drug Administration should address the mislabeling of the iodine content of prenatal/lactation supplements.

Influence of maternal thyroid hormones during gestation on fetal brain development

“…An explanation may be found in dietary changes. For example, processed foods in the U.S. are prepared with non-iodized salt, and consumption of these foods has increased (Council on Environmental Health et al, 2014). In addition, during pregnancy, iodine requirement is increased by 50-75%, due to a 30-50% increase in renal iodide clearance and trans-placental iodine transfer (Glinoer, 2007, McLeod and McIntyre, 2010).…”

“…In addition, during pregnancy, iodine requirement is increased by 50-75%, due to a 30-50% increase in renal iodide clearance and trans-placental iodine transfer (Glinoer, 2007, McLeod and McIntyre, 2010). However, only 15-20% of pregnant women take iodide supplements (Council on Environmental Health et al, 2014), which may account for the finding that both in the U.S. and U.K. approximately one third of pregnant women are at least mildly iodine deficient according to WHO criteria (Caldwell et al, 2011, Bath et al, 2013). This circumstance is of prime importance because the fetus receives TH in part from the mother during gestation.…”

Dietary Iodine Sufficiency and Moderate Insufficiency in the Lactating Mother and Nursing Infant: A Computational Perspective

“…The American Thyroid Association and the Endocrine Society have recommended that lactating women take vitamins containing 150 μg of iodide daily to supplement their dietary intake of iodide. This recommendation stems from NHANES reports of low individual maternal urinary iodide concentrations in women of childbearing age and pregnant women [ 73 – 75 ]. The NHANES data may be inadequate to draw population-based conclusions from using spot urines for iodide because small sample size [ 76 ].…”

Spatial analysis of Neonatal Congenital Hypothyroidism and Nitrate as an environmental pollutant in Isfahan Province during 2010-2013

“…[ 29 ] Furthermore, Council on Environmental Health (2014) documented increased vulnerability of thyroid gland to certain environmental pollutants (such as nitrate, thiocyanate, and perchlorate) in the condition of iodine deficiency. [ 30 ]…”