Iodine status in Norwegian preschool children and significance of dietary sources of iodine and parental socio-economic factors - A cross-sectional study

Iodine is an essential trace element with important physiological effects in the human body. Iodine is necessary for thyroid hormone synthesis. The hormones are needed for tissue development in the central nervous system, growth and brain development in children, and regulation of basal metabolic rate and macronutrient metabolism. Iodine deficiency is still a global threat despite international efforts to eliminate the condition. In recent years, major progress have been made towards elimination of iodine deficiency due to introduction of universal salt iodization programs. However, iodine deficiency is still the number one cause of preventable mental retardation in children. In Norway, goiter prevalence was high prior to introduction of fortification of cow fodder in 1950. Since then, iodine status of the Norwegian population have gradually improved. However, several studies have suggested that subgroups of the Norwegian population may be susceptible to iodine deficiency due to low intake of iodine-rich food sources including seafood and dairy products. Studies on iodine status in Norwegian preschool children (aged 4-6 years) are old and lacking. Study aims: Main aim of the present thesis was to determine and evaluate the iodine status of preschool children living in Bergen. Specific aims included investigations of possible associations between urinary iodine concentration and iodine-rich food sources and parental socio-economic factors. Associations between parental socio-economic factors and the children's intake of iodine-containing foods were also examined. Methods and materials: The present thesis is part of a larger intervention study. Habitual dietary intake was assessed by a semi-quantitative food frequency questionnaire. Iodine concentration was determined by inductively coupled plasma-mass spectrometry in non-fasting, spot urine samples. Results: Approximately 50% of the children consumed fish and other seafood less frequently than current Norwegian recommendations of two to three servings per week. Nearly all children consumed dairy products daily. The iodine status of the preschool children was adequate (133 µg/L). Intake of fatty fish (OR = 1.95, 95% CI = 1.01-3.77, p = 0.048) and sweet milk (OR = 2.17, 95% CI = 1.07-4.38, p = 0.031) were associated with sufficient iodine status. Weak correlations were observed between iodine status and intake of iodine-rich food sources and between iodine status and parental socio-economic factors. In addition, unadjusted logistic regression models found higher socio-economic status to be associated with increased likelihood of a higher intake of seafood for dinner and dairy products among the children. Conclusions: The preschool children in this study had adequate iodine status, and intake of sweet milk and fatty fish were significant predictors of sufficient iodine status. Parental socio-economic status seemed to be associated with the children's intake of seafood and dairy products.Master i Klinisk ernæringNUCLI395MAMD-NUCL

Iodine status in Norwegian preschool children and associations with dietary iodine sources: the FINS-KIDS study

Iodine is an essential trace element necessary for thyroid hormone synthesis. Iodine deficiency is a continuing public health problem despite international efforts to eliminate it. Studies on iodine status in preschoolers are scarce. Thus, the aims of the current study were to determine the iodine status and to investigate possible associations between urinary iodine concentration (UIC) and estimated 24 h iodine extraction (UIE) and iodine-rich foods.publishedVersio

Iodine status in Norwegian preschool children and associations with dietary iodine sources: the FINS-KIDS study

Purpose. Iodine is an essential trace element necessary for thyroid hormone synthesis. Iodine deficiency is a continuing public health problem despite international efforts to eliminate it. Studies on iodine status in preschoolers are scarce. Thus, the aims of the current study were to determine the iodine status and to investigate possible associations between urinary iodine concentration (UIC) and estimated 24 h iodine extraction (UIE) and iodine-rich foods. Methods. Data are cross-sectional baseline data, obtained from the two-armed randomized controlled dietary trial “Fish Intervention Studies-KIDS” (FINS-KIDS) conducted in Bergen, Norway. UIC was determined by inductively coupled plasma-mass spectrometry in spot urine samples. Inadequate UIC was defined as median < 100 µg/L, and low estimated 24 h UIE as < 65 µg/day. Habitual dietary intake was assessed by a short food frequency questionnaire. Logistic regression models were used to investigate possible associations between UIC and estimated 24 h UIE and iodine-rich dietary sources including seafood, dairy products and eggs. Iodine/creatinine ratio (I/Cr) was also estimated. Results. Urinary spot samples were obtained from 220 children. The median (interquartile range) UIC and estimated 24 h UIE was 132 (96) µg/L, and 65 (55) µg/day, respectively. The majority of children had an estimated I/Cr ratio within 100–199 µg/g. Intake of sweet milk < 2 times/day versus ≥ 2 times/day was associated with UIC < 100 µg/L (OR 2.17, 95% CI 1.07–4.38, p = 0.031). Intake of dairy products (OR 3.59, 95% CI 1.13–11.43, p = 0.031) and sweet milk (OR 2.77, 95% CI 1.37–5.61, p = 0.005) < 2 times/day versus ≥ 2 times day was associated with estimated 24 h UIE < 65 µg/day. Conclusions. The preschoolers had adequate iodine status. Low intake of sweet milk and dairy products were associated with low iodine status