Prevalence of iodine inadequacy in Switzerland assessed by the estimated average requirement cut-point method in relation to the impact of iodized salt

Abstract

Objective: To assess the iodine status of Swiss population groups and to evaluate the influence of iodized salt as a vector for iodine fortification. Design: The relationship between 24 h urinary iodine and Na excretions was assessed in the general population after correcting for confounders. Single-day intakes were estimated assuming that 92 % of dietary iodine was excreted in 24 h urine. Usual intake distributions were derived for male and female population groups after adjustment for within-subject variability. The estimated average requirement (EAR) cut-point method was applied as guidance to assess the inadequacy of the iodine supply. Setting: Public health strategies to reduce the dietary salt intake in the general population may affect its iodine supply. Subjects: The study population (1481 volunteers, aged ≥15 years) was randomly selected from three different linguistic regions of Switzerland. Results: The 24 h urine samples from 1420 participants were determined to be properly collected. Mean iodine intakes obtained for men (n 705) and women (n 715) were 179 (SD 68·1) µg/d and 138 (SD 57·8) µg/d, respectively. Urinary Na and Ca, and BMI were significantly and positively associated with higher iodine intake, as were men and non-smokers. Fifty-four per cent of the total iodine intake originated from iodized salt. The prevalence of inadequate iodine intake as estimated by the EAR cut-point method was 2 % for men and 14 % for women. Conclusions: The estimated prevalence of inadequate iodine intake was within the optimal target range of 2-3 % for men, but not for women.

Iodine Status Assessment in Children: Spot Urine Iodine Concentration Reasonably Reflects True Twenty-Four–Hour Iodine Excretion Only When Scaled to Creatinine

“…However, caution has to be taken here regarding the percentage of subjects below the respective EAR due to the intraindividual day-to-day variability, being present also with 24-hour urine collections. As reported by Haldimann et al (30), and also discussed by Zimmermann and Andersson (4), appropriate adjustment for intraindividual and interindividual variation of iodine excretion can result in a substantial attenuation of the proportion of individuals lying below the EAR.…”

“…So far, few studies have investigated alternative approaches to estimate 24h-UIE from spot UIC values, and the existent literature only refers to studies conducted in adults (8,9,16,30). Moreover, the Institute of Medicine (24) has proposed one equation to simplify the calculation of daily iodine intake, using approximated values based on iodine bioavailability, observed urine volumes and weight; however, this approach represents only an approximation without considering the obviously common interindividual and intraindividual variations in urine volume that can confound the Institue of Medicine suggested method.…”

Examination of iodine status in the German population: an example for methodological pitfalls of the current approach of iodine status assessment

“…This assumption was questioned repeatedly in the past, as mean urine volume of adults may easily amount to 2 L/day and more [18,[30][31][32]. Accordingly, in a very recent investigation of iodine status in Switzerland, median iodine concentration (measured in 1420 24-h urines) was only 60-70 µg/L, whereas 24-h iodine excretion indicated risk of inadequate iodine status in only 2 % of men and 14 % of women [31].…”

“…This assumption was questioned repeatedly in the past, as mean urine volume of adults may easily amount to 2 L/day and more [18,[30][31][32]. Accordingly, in a very recent investigation of iodine status in Switzerland, median iodine concentration (measured in 1420 24-h urines) was only 60-70 µg/L, whereas 24-h iodine excretion indicated risk of inadequate iodine status in only 2 % of men and 14 % of women [31]. Something roughly similar could be observed in the present representative pool of spot urines of the German adult population: Despite a median iodine concentration of only about 50-60 µg/L, estimated 24-h iodine excretion was twice as high (113 µg/ day), again suggesting an average urine volume of about 2 L. These data emphasize that-simply influenced by urine volume-the WHO assessment parameter iodine concentration can vary substantially even in large populations and may thus lead to considerable misinterpretations of actual iodine nutrition status.…”

menuCH - Swiss Nutrition Survey 2014-2015

“…The salt added at the table (salt shaker) is an important source of sodium intake which could be reduced directly by every person unlike the content of salt in processed foods, which depends on action by the food industry. Salt is also used as a carrier of iodine and fluorine in Switzerland to prevent nutritional deficiencies and their adverse health consequences (38). Figure 50 Type of salt use at home, overall, by sex, age groups, linguistic and region educational level.…”