Cow milk is an important source of iodine for prenatal health, and switching to plant-based milk can lead to iodine insufficiencies

Abstract

Iodine insufficiencies are common among many populations, particularly pregnant women. One of the main functions of iodine is making thyroid hormone. The 2 main hormones that iodine influences are triiodothyronine and thyroxine. Thyroid hormone affects metabolism of most tissues. For the average adult, the recommended dietary allowance (RDA) for iodine is 150 µg. During certain stages of life, such as pregnancy, lactation, and infancy, the importance of iodine is even greater as it supports brain, bone, and organ development. The RDA for iodine during pregnancy is 220 µg and, during breastfeeding, the RDA is 290 µg. Consuming enough iodine in the diet during pregnancy helps support fetal neurodevelopment. Iodine is found in several food sources such as seafood and iodized salt; however, dairy products are one of the major sources of iodine in American diets. It is important to note that only bovine milk products are rich in this mineral. One cup of milk provides 39% and 57% of the daily iodine needs for the average adult woman and pregnant woman, respectively. As the Dietary Guidelines for Americans (DGA) recommend limiting sodium intake, which includes iodized salt, dairy may be an especially important source of iodine. However, according to the USDA, about 90% of the US population does not meet the dairy recommendations presented in the DGA. In recent years, plant-based diets have received a lot of attention. A market for plant-based milk alternatives has grown and includes a variety of options such as almond, soy, and oat milk. Plant-based milks do not naturally contain iodine and are typically not fortified with iodine. Women of childbearing age who drink plant-based milks instead of cow milk have lower urinary iodine concentrations than women who consume cow milk. This review will focus on the importance of iodine in the diet to support prenatal health, lactation, and infant health.