Iodine Nutrition Improves in Latin America

Abstract

Iodine deficiency has been a public health problem in most Latin American countries. Massive programs of salt iodization have achieved great progress toward its elimination but no consistent monitoring has been applied. We used the ThyroMobil model to visit 163 sites in 13 countries and assess randomly selected schoolchildren of both genders 6-12 years of age. The median urinary iodine concentration (8208 samples) varied from 72 to 540 microg/L. One national median was below the recommended range of 100-200 microg/L; five were 100-200 microg/L, and seven were higher than 200 microg/L, including three greter than 300 microg/L. Urinary iodine concentration correlated with the iodine content of salt in all countries. Median values of thyroid volume were within the normal range for age in all countries, but the goiter prevalence varied markedly from 3.1% to 25.0% because of scatter. The median iodine content of salt from local markets (2734 samples) varied from 5.9 parts per million (ppm) to 78 ppm and was greater than 15 ppm in 83.1% of all samples. Only seven countries had higher than 15 ppm iodine in 80% of the samples, and only three had greater than 15 ppm in at least 90%. Iodized salt was available at retail level in all countries but its median iodine content was within the recommended range (20-40 ppm) in only five. This study, the first to apply a standardized assessment strategy to recent iodine nutrition in Latin America, documents a remarkable success in the elimination of iodine deficiency by iodized salt in all but 1 of the 13 countries. Some iodine excess occurs, but side effects have not been reported so far, and two countries have already decreased their legal levels of salt iodization and improved the quality control of iodized salt, in part because of our results. The present work should be followed by regular monitoring of iodine nutrition and thyroid function, especially in the countries presently exposed to iodine excess.

Iodine nutritional status in Brazil: a meta-analysis of all studies performed in the country pinpoints to an insufficient evaluation and heterogeneity

“…We have found only 24 studies published between 1997 and 2013 eligible for this systematic review (16, (Table 1). A total of 26,148 subjects were subscribed for UIE assessment between 1997 and 2013.…”

“…In accordance with Resolution RDC nº 130 (2003), it was deemed fit, for human consumption, salt content that corresponded to 20-60 ppm of iodine concentration and this recommendation have been prevailed for ten years (14). However, in the mean time, data from the ThyroMobil Project in Latin America, identified Brazil (with 17 sentinel sites and a total of 1,563 school children evaluated) as a country of excessive iodine consumption, with a mean urinary iodine excretion (UIE) concentration of 360 µg/L (15,16). Consequently, the levels of salt iodization were recently reduced to 15 to 45 milligrams of iodine per kilogram of product (http://www.in.gov.br) (17).…”

Desenvolvimento de um método para a determinação da iodúria e sua aplicação na excreção urinária de iodo em escolares brasileiros

“…Assim, em 2000 realizou-se outro levantamento em 21 municípios das regiões norte, centrooeste e sudeste, sob o patrocínio da ICCIDD (3,10,33), nos municípios onde o inquérito revelado neste trabalho havia evidenciado deficiência leve e moderada. Apesar do número menor de amostras (n = 1.013), observou-se, surpreendentemente, elevação da excreção urinária de iodo em relação a 1994, sendo que 86,5% dos escolares apresentava iodúria acima de 300 µg/L, dos quais metade acima de 500 µg/L (3).…”

“…Baseados no presente estudo, que indicava deficiência na ingestão de iodo em 1994 e de novas evidências provenientes de estudos limitados (10,(33)(34)(35), mas indicativos de excesso na ingestão de iodo, recomendamos que o Ministério da Saúde retome suas avaliações periódicas sobre o estado nutricional de iodo e cumpra a legislação vigente que trata da iodação do sal no Brasil, identificando os fatores que prejudicam sua efetividade, obedecendo, inclusive, às determinações da OMS; além disso, consideramos fundamental que os profissionais da saúde e dos órgãos governamentais sejam conscientizados permanentemente sobre o conceito de distúrbios associados à carência e ao excesso de iodo.…”

“…Além disso, estudos populacionais comparativos demonstram a correlação entre os valores obtidos por coleta de amostras de urina ao acaso (coleta casual) e as amostras de urina de 24 horas, em razão da distribuição gaussiana da concentração de iodo na urina (9,10).…”