Review of Iodine Nutrition in Iranian Population in the Past Quarter of Century.

CONTEXT

Iodine deficiency is one of the most important health problems worldwide. The overall aim of this study was a narrative review of the past and present status of iodine nutrition in the Iranian population to gather and provide valuable background data in this field for future studies.

EVIDENCE ACQUISITION

For this narrative literature review study, published internal (SID, Iran doc, Iran medex) and international (Web of knowledge, Pubmed, SCOPUS) source studies were searched using the following medical subject heading terms: Iodine, IDD (iodine deficiency disorders), UIC (urinary iodine concentration), Goiter, IQ (intelligence quotient), thyroid hormone, Iodine and pregnancy, Iodine and breast feeding, as well as Iodized salt, reporting the prevalence of iodine deficiency and iodine nutrition status of different target populations in Iran over 25 years, between 1988 - 2014, were assessed. We found 185 abstracts by literature search, of which, 161 papers that were as case reports, animal study, with lack of regional or national data were excluded after full text evaluation. Finally 24 full papers covering regional or national data on iodine nutrition of the study population were eligible for our review.

RESULTS

Iodine deficiency, as a nutritional problem, had been identified in Iran since 1968. In the years 1987 - 1989, a few studies were done to define the prevalence of iodine deficiency in the country. The first nation-wide survey was performed in 14 provinces. Based on this survey all provinces were suffering of endemic goiter. In 1989, iodine deficiency was recognized as a major problem for community health. In 1990, salt factories began to produce iodized salt and in 1996, the second national survey was performed in 26 provinces. This survey indicated that 40% of boys and 50% of girls have goiter, with a median urinary iodine excretion of 205 µg/L. The 3rd national survey in 2001 showed that the total goiter rate is 9.8% and median UIC of 165 μg/L. In 2007, the 3th national survey was conducted 17 years after iodized salt consumption by Iranian households. In this study the total goiter rate and median urinary iodine was 5.7% and 145 μg/L, respectively. The 5th national survey conducted in 2013, showed household consumption of iodized salt for all provinces was 98% and the median urinary iodine of school children was 161 μg/L. Following the 5th national survey, the 1st national survey of the iodine status and thyroid function of pregnant women, conducted in 10 provinces in the different region of the country, documented a median UIC for pregnant women of 87.3 µg/L, results of this national survey clarified that despite iodine sufficiency of school children in Iran, pregnant women have moderate iodine deficiency and need iodine supplementation.

CONCLUSIONS

The success of iodine deficiency control program depends on well designed programmatic steps and mandatory iodized salt consumption in certain situations. The iodine intake of school children is sufficient, however, Iranian pregnant women are suffering from moderate iodine deficiency and need iodine supplementation.