Karim Bougma

Iodine and Mental Development of Children 5 Years Old and Under: A Systematic Review and Meta-Analysis

Several reviews and meta-analyses have examined the effects of iodine on mental development. None focused on young children, so they were incomplete in summarizing the effects on this important age group. The current systematic review therefore examined the relationship between iodine and mental development of children 5 years old and under. A systematic review of articles using Medline (1980–November 2011) was carried out. We organized studies according to four designs: (1) randomized controlled trial with iodine supplementation of mothers; (2) non-randomized trial with iodine supplementation of mothers and/or infants; (3) prospective cohort study stratified by pregnant women’s iodine status; (4) prospective cohort study stratified by newborn iodine status. Average effect sizes for these four designs were 0.68 (2 RCT studies), 0.46 (8 non-RCT studies), 0.52 (9 cohort stratified by mothers’ iodine status), and 0.54 (4 cohort stratified by infants’ iodine status). This translates into 6.9 to 10.2 IQ points lower in iodine deficient children compared with iodine replete children. Thus, regardless of study design, iodine deficiency had a substantial impact on mental development. Methodological concerns included weak study designs, the omission of important confounders, small sample sizes, the lack of cluster analyses, and the lack of separate analyses of verbal and non-verbal subtests. Quantifying more precisely the contribution of iodine deficiency to delayed mental development in young children requires more well-designed randomized controlled trials, including ones on the role of iodized salt.

Ethiopian pre-school children consuming a predominantly unrefined plant-based diet have low prevalence of iron-deficiency anaemia

OBJECTIVE Children from low-income countries consuming predominantly plant-based diets but little animal products are considered to be at risk of Fe deficiency. The present study determined the Fe status of children from resource-limited rural households. DESIGN A cross-sectional study. SETTING Twenty six kebeles (the smallest administrative unit) from six zones of the Amhara region, Ethiopia. SUBJECTS Children aged 54-60 months (n 628). RESULTS Grain, roots or tubers were the main dietary components consumed by 100 % of the study participants, followed by pulses, legumes or nuts (66·6 %). Consumption of fruit and vegetables (19·3 %) and meat, poultry and fish (2·2 %) was low. Children had a mean dietary diversity score of 2·1 (sd 0·8). Most children (74·8 %, n 470) were in the lowest dietary diversity group (1-2 food groups). Rate of any morbidity in the preceding 14 d was 22·9 % (n 114). Infection or inflammation (α1-acid glycoprotein >1·2 g/l) was present in 30·2 % (n 184) of children. Children had a high rate of stunting (43·2 %). Of the total sample, 13·6 % (n 82) of children were anaemic, 9·1 % (n 57) were Fe deficient and 5·3 % (n 32) had Fe-deficiency anaemia. Fe-deficiency erythropoiesis was present in 14·2 % (n 60) of children. CONCLUSIONS Despite consuming a predominantly plant-based diet and little animal-source foods, there was a low prevalence of Fe-deficiency anaemia. This illustrates that dietary patterns can be inharmonious with Fe biochemical status; thus, Fe-related interventions require biochemical screening.

Evaluation of the effects of iodized salt on the mental development of preschool-aged children: a cluster randomized trial in northern Ethiopia

Abstract A cluster randomized effectiveness trial was used to examine the effects on mental development of introducing iodized salt to children 4 to 6 years of age in Ethiopia, where there were reportedly high levels of iodine deficiency. Sixty district clusters were randomized to receive iodized salt early at their markets with assistance from regular salt distributors or later as introduced by market forces. At pre‐ and post‐iodization, 1602 children were given cognitive/language tests (namely School Readiness, WPPSI verbal reasoning, WPPSI Matrix reasoning), and mothers were interviewed concerning demographics, nutrition and health. Childrens weight, height, urine and a blood sample were taken. Analyses of covariance, adjusting for clustering and baseline levels were conducted. Urinary iodine concentrations were significantly higher at endline in the intervention children than controls though both medians were above threshold. Overall, less than 5% were anemic. There were no significant main effect differences between groups on the cognitive/language tests, but there were effect modifiers, namely mothers education, childs sex and diet. For example, the intervention group performed better on the school readiness test than controls if their mothers had attended school, but not otherwise. In conclusion, the data are consistent with negative findings from studies where children 6 to 12 years were supplemented with an iodine capsule, indicating that the benefits of iodine, in salt or capsule form, for brain development may be restricted to children under 3 years. Yet, benefits may be tied to those with more educational resources or may compensate for conditions of disadvantage.

Association of serum selenium with thyroxin in severely iodine-deficient young children from the Amhara region of Ethiopia

Background/Objectives:Selenium (Se) as part of glutathione peroxidase and iodothyronine deiodinase enzymes influences thyroid metabolism. This study investigated the association of serum Se levels with thyroid metabolism of severely iodine-deficient young children from the Amhara region of Ethiopia.Subjects/Methods:In a cross-sectional study, Se, thyroid-stimulating hormone, total thyroxin, total triiodothyronine and thyroglobulin in serum of children (N=628) 54–60 months of age from the Amhara region, Ethiopia, were analyzed. In addition, iodine in urine and household salt was analyzed, and the presence of goiter was assessed.Results:The median serum Se concentration was 61.4 μg/l (10.7–290.9 μg/l). Selenium deficiency (serum Se <70 μg/l) was detected in 57.8% (N=349) of the children. The median urinary iodine concentration (UIC) was 9.8 μg/l. The majority (86.6%, N=449) of children had UIC below the recommended value (100 μg/l). In addition, 59.8% (N=310) of children were severely iodine deficient (UIC<20 μg/l). Only 12.7% of salt samples had iodine. Goiter was present in 44.6% (N=280) of the children. Selenium-deficient children had higher serum thyroxin (T4) than children with normal serum Se concentration (P<0.001).Conclusions:Serum Se was negatively associated with T4 level in young children from the Amhara region of Ethiopia and may endanger the effectiveness of the salt iodization program.

Selenium inadequacy hampers thyroid response of young children after iodine repletion

Selenium (Se) is an integral component of iodothyronine deiodinase, glutathione peroxidase and thioredoxin reductase enzymes and thus is important for normal thyroid function. This study investigated the influence of Se inadequacy on thyroid response of iodine-replete young children. Serum thyroxine (T4), triiodothyronine (T3), thyroglobulin (Tg), thyroid stimulating hormone (TSH), and Se were analyzed in 54-60 mo old children (n = 628) from the Amhara region of Ethiopia before salt iodization was commenced; analyses were repeated (n = 555) 15 mo after iodized salt became available. Iodized salt coverage increased from 12.2% to 91.6% of households. Median urinary iodine concentration (UIC) among children increased from 9 μg/l to 167 μg/l (p < 0.001). In addition, all thyroid indices except T3 showed significant improvement (p < 0.05). Nearly, half of the study children (49.1%) had Se inadequacy (serum Se < 70 μg/l). Serum Se was significantly correlated with T3 (r = 0.38, p < 0.001), T4 (r = 0.15, p < 0.001), TSH (r=-0.205, p < 0.001) and Tg (r= -0.11, p < 0.01) concentrations 15 mo after iodine repletion; baseline serum Se and T4(r= -0.22, p < 0.01) were inversely correlated. Despite adequate iodine status, children with low serum Se had lower serum T4 (p = 0.003) and T3(p < 0.001) but higher TSH concentration (p = 0.003). In the partial least square regression model, Se was among the latent variables significantly explaining T4 and T3. Results of the present study suggest that Se inadequacy negatively affects the thyroid metabolism of iodine-replete children and may present a substantial public health concern thus emphasize the need to consider correction of Se status for normal thyroid function as well as for benefits from its diverse biological roles.