A Review of the Potential Interaction of Selenium and Iodine on Placental and Child Health

Abstract

A healthy pregnancy is important for the growth and development of a baby. An adverse pregnancy outcome is associated with increased chronic disease risk for the mother and offspring. An optimal diet both before and during pregnancy is essential to support the health of the mother and offspring. A key mediator of the effect of maternal nutrition factors on pregnancy outcomes is the placenta. Complicated pregnancies are characterized by increased oxidative stress in the placenta. Selenium and iodine are micronutrients that are involved in oxidative stress in placental cells. To date, there has been no comprehensive review investigating the potential synergistic effect of iodine and selenium in the placenta and how maternal deficiencies may be associated with increased oxidative stress and hence adverse pregnancy outcomes. We undertook a hypothesis-generating review on selenium and iodine, to look at how they may relate to pregnancy complications through oxidative stress. We propose how they may work together to impact pregnancy and placental health and explore how deficiencies in these micronutrients during pregnancy may impact the future health of offspring.

Keywords: iodine; micronutrients; oxidative stress; placenta; pregnancy; selenium.

Figure 1

Deficiencies (↓) in selenium and iodine result in placental oxidative stress which may contribute to adverse pregnancy outcomes and hence increased (↑) risk of chronic disease in offspring.

Figure 2

Deficiencies (↓) in iodine result in decreased (↓) T3 (triiodothyronine) and T4 (thyroxine) levels but increased (↑) TSH (thyroid-stimulating hormone) which results in more H₂O₂ (hydrogen peroxide). Antioxidants such as GPx (glutathione peroxidase) and TRx (thioredoxin reductase) are selenoproteins and in the presence of adequate selenium can convert H₂O₂ to H₂O (water). However, if there is a selenium deficiency (↓), H₂O₂ accumulates and can result in increased oxidative stress and inflammation. Deiodinases (DIO) are selenoproteins and deiodinase II converts T4 to T3.