GLOBAL ENDOCRINOLOGY: Global perspectives in endocrinology: coverage of iodized salt programs and iodine status in 2020

Abstract

Iodine deficiency has multiple adverse effects on growth and development. Diets in many countries cannot provide adequate iodine without iodine fortification of salt. In 2020, 124 countries have legislation for mandatory salt iodization and 21 have legislation allowing voluntary iodization; as a result, 88% of the global population uses iodized salt. For population surveys, the urinary iodine concentration (UIC) should be measured and expressed as the median, in μg/L. The quality of available survey data is high: UIC surveys have been done in 152 out of 194 countries in the past 15 years; in 132 countries the studies were nationally representative. The number of countries with adequate iodine intake has nearly doubled from 67 in 2003 to 118 in 2020. However, 21 countries remain deficient, while 13 countries have excessive intakes, either due to excess groundwater iodine, or over-iodized salt. Iodine programs are reaching the poorest of the poor: of the 15 poorest countries in the world, 10 are iodine sufficient and only three (Burundi, Mozambique and Madagascar) remain mild-to-moderately deficient. Nigeria and India have unstable food systems and millions of malnourished children, but both are iodine sufficient and population coverage with iodized salt is a remarkable 93% in both. Once entrenched, iodine programs are often surprisingly durable even during national crises; for example, war-torn Afghanistan and Yemen are iodine sufficient. However, equity of iodized salt programs within countries remains an important issue. In summary, continued support of iodine programs is needed to sustain these remarkable global achievements, and to reach the remaining iodine-deficient countries.

The Nutritional Supply of Iodine and Selenium Affects Thyroid Hormone Axis Related Endpoints in Mice

“…Worldwide, there are still areas where the intake of either or both trace elements is low [4,5]. For iodine, extensive efforts have been undertaken in numerous countries to improve the daily intake by mandatory iodine fortification of foods for example iodination of table salt [4,6].…”

“…Worldwide, there are still areas where the intake of either or both trace elements is low [4,5]. For iodine, extensive efforts have been undertaken in numerous countries to improve the daily intake by mandatory iodine fortification of foods for example iodination of table salt [4,6]. Factors that play a decisive role in the supply of these nutrients include deterioration of soil conditions [7], which affects the content of food, but also the increasing prevalence of dietary habits that may increase the risk of inadequate iodine and Nutrients 2021, 13, 3773 2 of 16 selenium intake, particularly in Europe.…”

The Consumption of Food-Based Iodine in the Immediate Pre-Pregnancy Period in Madrid Is Insufficient. San Carlos and Pregnancy Cohort Study

“…Adequate iodine stores as well as an increase in iodine intake are needed to permit the physiological increase in maternal thyroid FT4 secretion characteristic of early stages of pregnancy [1]. However, dietary iodine deficiency is a relevant problem worldwide [7][8][9]. In fact, iodine deficit is still the most important cause of preventable neurocognitive dysfunction and motor disability in offspring [8,[10][11][12][13][14][15].…”

What Iodine Intervention Measures Should Be Taken in Different Water Iodine Areas? Evidence from a Cross-sectional Chinese Survey

“…There is clear evidence that both iodine deficiency and iodine excess can lead to thyroid dysfunction or disease [2][3][4][5]. Globally, 21 countries remain iodine deficient, and 13 countries have excess iodine intake [6]. Excess iodine intake in populations can result from diets that are naturally high in iodine or drinking water.…”

“…In South Korea and Japan, excessive iodine intake is primarily due to chronic iodine-rich seaweed ingestion [7,8]. In China, Djibouti and Somalia excess iodine intakes are due to high iodine in drinking water [6,9,10]. Most of the external environment in China is iodine deficient, and iodine deficiency disorders (IDD) were once widely prevalent across the country.…”