A History of the Elimination of Iodine Deficiency Disorders in the Americas: A Dramatic Achievement and Lessons Learned.

Iodine is essential for the synthesis of thyroid hormones, which regulate cell metabolism, growth, and development. Although iodine deficiency (ID) causes adverse health effects across the lifespan, it is particularly problematic in pregnancy, when it can lead to irreversible fetal brain damage. A high prevalence of severe ID, manifesting as endemic goiter and cretinism, predated the arrival of European explorers in the Americas. Early 20th century surveys showed that most countries in the Western Hemisphere had regions with a goiter prevalence >50%. In North America, the introduction of iodized salt led to the elimination of ID by the 1950s. Although most Latin American countries passed laws mandating salt iodization in the 1950s-1960s, initial programs met with limited success because laws were unenforced, monitoring was absent, and the importance of iodine nutrition was inadequately communicated. A renewed interest in ID prevention arose in the 1970s-1980s, when 3 Andean countries were the first in Latin America to implement effective salt iodization programs. Over the last 3 decades there has been a stronger political commitment to ID prevention across the region, alignment with the broader nutrition and development agenda, and a widespread recognition of optimal iodine nutrition as a fundamental human right. Currently, 92% of households in Latin America consume adequately iodized salt, and urinary iodine concentrations in schoolchildren reflect optimal iodine nutrition across the region. However, additional work remains. It is essential to ensure ongoing government commitment; to monitor population iodine status and the production, quality, and household consumption of iodized salt; and to maintain advocacy and communication strategies. Universal salt iodization programs must be harmonized with efforts to reduce salt intake for cardiovascular disease prevention. Ensuring optimal iodine nutrition in pregnant women, who may remain deficient even when intakes in schoolchildren are optimized, requires particular attention.