Adequacy Assessment of a Universal Salt Iodization Program Two Decades after Its Implementation: A National Cross-Sectional Study of Iodine Status among School-Age Children in Tunisia

Abstract

In the framework of a worldwide policy to eliminate iodine deficiency (ID) disorders, universal salt iodization was adopted in Tunisia two decades ago. The present study aims to evaluate this strategy, using both performance and impact indicators. A total of 1560 children, aged 6–12 years, were randomly sampled using a national, two-stage, stratified, cross-sectional cluster survey in 2012. Urinary iodine concentration (UIC) of the subjects, and household salt iodine content, were analyzed. The national median UIC was 220 µg/L (95% confidence interval (CI): 199–241), indicating an acceptable iodine status at the population level. Only 11.4% (95% CI: 8.6–14.9) of the children had UIC <100 µg/L, but with large regional disparities (4.3% to 25.5%, p < 0.01); however, more than a quarter of the subjects were at risk of adverse health consequences due to iodine excess. Children from households of low socio-economic levels were more prone to inadequate UIC. The national median iodine concentration of household salt was 22 mg/kg (95% CI: 21–23). Only half of the households used adequately iodized salt (15–25 ppm), with large regional disparities. National ID rates are now well below the target criteria of WHO (World Health Organization) certification (<20% of children with UIC <50 µg/L and <50% with UIC <100 µg/L). The coverage of adequately iodized salt fell short in meeting the goals of USI (Universal Salt Iodization), i.e., >90% of households. Regular monitoring of iodized salt production lines must be strengthened with involvement by producers.

Flaws of universal salt iodization programmes in nutrition transition contexts: is there a risk of a double burden of inadequate iodine intake and excess adiposity? A case study in Tunisia

“…[62,63]. Also, as part of a worldwide strategy to tackle iodine de ciency disorders [16], Tunisia has implemented a USI program since 1995 [18]. Failure in the program monitoring and control has resulted in inadequately iodized salt (as a quarter of the commercialized salt is excessively iodized) [22].…”

“…The present study is a based on a secondary analysis of data collected in a previously documented national cross-sectional survey conducted in Tunisia between May and June 2012: 6-12 y. school-children (n = 1560) were surveyed using a random, strati ed, clustered sample [18].…”

“…The Sandell-Kholthoff method was used to assess urinary iodine concentration (UIC) [16]. Details related to technique precision and validation were previously published [18]. The WHO cut-offs for assessment of population iodine status based on the median UIC (µg/L) were used to classify school-age children as follow [16,25]: UIC < 100 de ned iodine de ciency (ID), UIC ≥ 200 de ned iodine intake above requirements (IAR 200 ) and UIC ≥ 300 de ned excess of iodine status(IE 300 ).…”

“…The population characteristics have been previously published [18]: 1560 school children were included in the study, and their mean age was 9. Co-occurrence of inadequate iodine and anthropometric status There was no difference in prevalence between girls and boys, whatever the co-occurrence of inadequate iodine and anthropometric status considered ( Table 1).…”

“…Also, in the context of the nutrition transition, the salt-rich westernized diet which underlies the progression of hypertension [4,5,20,21]. As for control of iodine de ciency, mandatory salt iodization had been implemented in speci c areas since 1984, but the national USI program was adopted in 1995 and launched in 1996 [18,22]. Its evaluation in 2012 showed some success regarding control of iodine de ciency, but also a high proportion of excess iodine intake, partly in relation with defaults in the salt iodization process and its monitoring [22].…”