Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: Results from the Avon Longitudinal Study of Parents and Children (ALSPAC)

Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.
The Lancet (Impact Factor: 45.22). 05/2013; 382(9889). DOI: 10.1016/S0140-6736(13)60436-5
Source: PubMed


BACKGROUND: As a component of thyroid hormones, iodine is essential for fetal brain development. Although the UK has long been considered iodine replete, increasing evidence suggests that it might now be mildly iodine deficient. We assessed whether mild iodine deficiency during early pregnancy was associated with an adverse effect on child cognitive development. METHODS: We analysed mother-child pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort by measuring urinary iodine concentration (and creatinine to correct for urine volume) in stored samples from 1040 first-trimester pregnant women. We selected women on the basis of a singleton pregnancy and availability of both a urine sample from the first trimester (defined as ≤13 weeks' gestation; median 10 weeks [IQR 9-12]) and a measure of intelligence quotient (IQ) in the offspring at age 8 years. Women's results for iodine-to-creatinine ratio were dichotomised to less than 150 μg/g or 150 μg/g or more on the basis of WHO criteria for iodine deficiency or sufficiency in pregnancy. We assessed the association between maternal iodine status and child IQ at age 8 years and reading ability at age 9 years. We included 21 socioeconomic, parental, and child factors as confounders. FINDINGS: The group was classified as having mild-to-moderate iodine deficiency on the basis of a median urinary iodine concentration of 91·1 μg/L (IQR 53·8-143; iodine-to-creatinine ratio 110 μg/g, IQR 74-170). After adjustment for confounders, children of women with an iodine-to-creatinine ratio of less than 150 μg/g were more likely to have scores in the lowest quartile for verbal IQ (odds ratio 1·58, 95% CI 1·09-2·30; p=0·02), reading accuracy (1·69, 1·15-2·49; p=0·007), and reading comprehension (1·54, 1·06-2·23; p=0·02) than were those of mothers with ratios of 150 μg/g or more. When the less than 150 μg/g group was subdivided, scores worsened ongoing from 150 μg/g or more, to 50-150 μg/g, to less than 50 μg/g. INTERPRETATION: Our results show the importance of adequate iodine status during early gestation and emphasise the risk that iodine deficiency can pose to the developing infant, even in a country classified as only mildly iodine deficient. Iodine deficiency in pregnant women in the UK should be treated as an important public health issue that needs attention. FUNDING: None.

265 Reads
  • Source
    • "Inadequate intake of iodine leads to insufficient production of these hormones, resulting in disease states collectively known as Iodine Deficiency Disorders (IDD) (Zimmermann, 2011, 2012). Iodine deficiency stands as a major public health problem, particularly for young children and pregnant women (WHO, 2004); the most damaging disorders are related to iodine deficiency during gestation (Zimmermann, 2009, 2012), that can result in adverse childhood cognitive outcomes (Zimmermann, 2011; Bath et al., 2013; Henrichs et al., 2013). Although iodine deficiency is often thought to be a problem of developing countries, industrialized countries are not immune; in Europe, WHO (2007) reported that in 11 out of 40 countries the population has insufficient iodine intake [with Urinary Iodine Concentrations (UIC) below 100 μg/L]. "

    Full-text · Article · Dec 2015 · Science of The Total Environment
    • "Iodine deficiency disorders (IDD) result in several metabolic changes including goitre and hypothyroidism which can occur at any stage of life, but the most devastating consequences take place during foetal development and childhood, with stillbirth , miscarriages, poor growth, and cognitive impairment (Andersson et al., 2012). Although cretinism is the most extreme manifestation, of considerably greater significance are the more subtle degrees of mental impairment that lead to poor school performance, reduced intellectual ability, and impaired work capacity (Bath et al., 2013). Iodine deficiency is the world's greatest single cause of preventable brain damage, and this fact is the primary motivation behind the current worldwide drive to eliminate iodine deficiency (WHO, 2007). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Marine fish are a rich source of iodine in the human diet. Exogenous feeding under captivity opens the possibility of tailoring fish composition with health valuable nutrients, such as iodine, and establishing it as a functional food. A study was undertaken to test the efficacy of various dietary iodine supplemental forms on the growth performance of gilthead seabream and assess the effects on sensory attributes and nutritional value of fillets. Duplicate groups of 35 seabream (IBW: 252 g) were fed over 118 days: a) control diet (CTRL) with 3 mg I kg− 1, supplied as potassium iodide; b) this same control diet supplemented with potassium iodide (diet KI: 26 mg I·kg− 1) or with ethylenediamine dihydroiodide (diet EDDI; 22 mg I·kg− 1); c) a fourth diet with 10% of Laminaria digitata, an iodine-rich macroalgae (diet LAM). At the end of the trial, fish doubled their initial weight, but irrespective of the iodine form used, the elevation of dietary iodine level had no effect (P > 0.05) on feed intake, growth rate, feed conversion, nutrient utilization or whole-body composition. Dietary iodine supplementation led to a significant increase (P < 0.05) of the iodine content in seabream fillets. In comparison to the CTRL treatment (0.13 mg·kg− 1), seabream fed KI and EDDI supplemented diets showed a significant enhancement (P < 0.05) of their fillet iodine content (0.17 mg·kg− 1). Feeding seabream with the iodine-rich brown algae L. digitata resulted in a significant (P < 0.05) 6.5-fold increase (0.84 mg·kg− 1 fillet) of fillet iodine content over the levels found in the CTRL treatment. Overall sensory difference between CTRL and fish fed supplemented diets was significant (P < 0.05) only for fish fed the EDDI diet. Steam-cooking elicited 13–20% losses of the iodine content of seabream fillets. Iodine supplementation had no effect (P > 0.05) on the fatty acid profile of seabream muscle. Dietary iodine-rich macroalgae was an effective and natural strategy to fortify muscle with iodine, showing that a 160 g portion of steam-cooked seabream fillets could cover approximately 80% of the Daily Recommended Intake for iodine and 370% of the Daily Adequate Intake of EPA + DHA for enhanced cardiovascular health in adults.
    No preview · Article · Feb 2015 · Aquaculture
  • Source
    • "In adults, mild-to-moderate iodine deficiency appears to be associated with higher rates of more aggressive subtypes of thyroid cancer and increases the risk of diffuse goiter, nontoxic and toxic nodular goiter and associated hyperthyroidism [1]. Although the prevalence of iodine deficiency in Europe has been reduced by almost 30% over the past decade, it still remains the leading cause of preventable intellectual impairment [2] [3] and is the primary motivation behind the current worldwide drive to eliminate iodine deficiency. Iodine is obtained from the diet and is primarily absorbed by the gastrointestinal tract in the inorganic anionic form of iodide. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background and objective: A nationwide survey of schoolchildren was conducted to detect regional differences in urinary iodine excretion in Latvia and to compare the results with data from the newborn thyroid-stimulating hormone (TSH) screening database as well with the results of a similar study performed in Latvia 10 years ago. Materials and methods: We conducted a cross-sectional school-based cluster survey of 915 children aged 9-12 years in 46 randomly selected schools in all regions of Latvia. Urine samples, questionnaires on the consumption of iodized salt and information on socioeconomic status were collected. TSH levels in newborns were also measured. Results: The median creatinine-standardized urinary iodine concentration (UIC) in our study was 107.3μg/g Cr. UIC measurements indicative of mild iodine deficiency were present in 31.6%, moderate deficiency in 11.9% and severe deficiency in 2.8% of the participants. The prevalence of iodine deficiency was the highest in the southeastern region of Latgale and the northeastern region of Vidzeme. The prevalence of TSH values >5mIU/L followed a similar pattern. The self-reported prevalence of regular iodized salt consumption was 10.2%. Children from urban schools had a significantly lower UIC than children from rural schools. Conclusions: Our findings suggest that although the overall median UIC in Latvian schoolchildren falls within the lower normal range, almost 50% of the schoolchildren are iodine deficient, especially in urban schools and in the eastern part of Latvia. The absence of a mandatory salt iodization program puts a significant number of children and pregnant women at risk.
    Full-text · Article · Dec 2014 · Medicina (Kaunas, Lithuania)
Show more


265 Reads
Available from
May 15, 2014