Iodine Deficiency: Achievements and Challenges for the 21st Century

Abstract

Iodine deficiency impairs the production of thyroid hormones, which has severe health consequences for child growth and development. Iodine deficiency is the most common cause of preventable mental impairment (Walker et al. in Lancet 369:145–57, [44], Zimmermann in Clin Endocrinol (Oxf.) 75:287–8, [50]). Mass iodization of salt provides a cost-effective way to improve iodine intake, with annual costs estimated at US$0.02–0.05 per child (UNICEF in The State of the World’s Children 2012: Children in an urban world, United Nations Children’s Fund, New York [40]), and over time has tremendously reduced the prevalence of severe iodine deficiency disorders across the globe. It is not certain, however, whether the iodine requirements of pregnant and lactating women are sufficiently covered by salt iodization programs. Although in many industrialized countries iodine deficiency has been addressed for centuries, the problem is currently recurring in some countries. New WHO recommendations on reducing sodium intake may also contribute to this. In contrast, several countries are now struggling with excessive intake of iodine. In this chapter, the following issues are discussed: What is the current global iodine status? Should additional measures be taken to cover iodine requirements during pregnancy and lactation? What are the causes of recurring iodine deficiency in industrialized countries, and what can we learn from this? Will reduction of salt intake influence the effectiveness of salt iodization programs? What measures should be taken to prevent excessive iodine intake? How can iodization programs be monitored better?