Association between household unavailability of iodized salt and child growth: evidence from 89 demographic and health surveys

Hotspots of un-iodized salt availability among Ethiopian households, evidence from the national survey data

BACKGROUND

Universal salt iodization was started before decades but there are communities using the un-iodized salt till now. More than one-tenth of the Ethiopian community uses un-iodized salt.

OBJECTIVE

This study aimed to identify the hotspots and associate factors of un-iodized salt availability in Ethiopia based on Ethiopian national household survey data.

METHODS

We conducted an in-depth analysis of the Ethiopian Demographic and Health Survey 2016 data. A total of 15,567 households were included in the final analysis. We cleaned and weighed the data using Stata version 16 software and descriptive outputs were reported in graphs and tables. We computed the weighted prevalence of un-iodized salt and prepared it for spatial analysis. Global-level spatial autocorrelation, hotspot analysis using the Getis-Ord Gi* statistics, and spatial interpolation using empirical Bayesian interpolation were executed using ArcGIS 10.3 to predict the magnitude of un-iodized salt at the national level. The binary logistics regression model was used to identify the contributing factors of un-iodized salt utilization. Model goodness of fit was tested with Hosmer and Lemeshow goodness-of-fit test (P = 0.96). Finally, the adjusted odds ratio (AOR) with 95% CI was reported to identify significant factors.

RESULTS

The magnitude of un-iodized salt availability was 14.19% (95% CI: 13.65, 14.75) among Ethiopian households. Un-iodized salt hotspots were found in Afar, Somalia, and Benishangul Gumuz regions. Compared to poorest wealth index: poorer (AOR = 0.55, 95% CI: 0.48, 0.64), middle (AOR = 0.51, 95% CI: 0.44, 0.60), richer (AOR = 0.55, 95% CI: 0.47, 0.64), and richest (AOR = 0.61, 95% CI: 0.50, 0.75); compared to uneducated household head: heads with secondary (AOR = 0.72, 95% CI: 0.60, 0.67) and above secondary (AOR = 0.54, 95% CI: 0.43, 0.67) education reduced the odds of un-iodized salt viability, while households living in highland (AOR = 1.16, 95% CI: 1.05, 1.29) had increased the odds of un-iodized salt availability.

CONCLUSION

More than a tenth of the households in Ethiopia uses un-iodized salt. Hotspots of un-iodized salt availability were found in Somali and Afar regions of Ethiopia. Better wealth index and education of the household heads reduces the odds of un-iodized salt availability while living in a high altitude above 2200 m increases the odds of un-iodized salt availability in Ethiopia.

Do maternal urinary iodine concentration or thyroid hormones within the normal range during pregnancy affect growth parameters at birth? A systematic review and meta-analysis

CONTEXT

Iodine, an essential constituent of thyroid hormones, is required for proper growth and development.

OBJECTIVE

To investigate whether growth parameters at birth are associated with maternal urinary iodine concentration (UIC) or normal ranges of thyroid hormones during pregnancy.

DATA SOURCES

Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, electronic databases (namely, MEDLINE, Web of Science, the Cochrane Library, Scopus, and Google Scholar) were searched between January 1988 and November 2018 to identify relevant articles.

DATA EXTRACTION

Data from the studies included were independently extracted by 2 investigators using standardized forms developed for this review.

DATA ANALYSIS

The pooled mean birth weight, length, and head circumference values, and 95% confidence intervals were estimated in newborns born to women with UIC < 150 and UIC ≥150 μg/L during pregnancy. Possible linear or nonlinear associations between maternal UIC and the aforementioned anthropometric measures were evaluated. A narrative synthesis of the data was performed for thyroid hormones with levels within the normal range.

RESULTS

Of the 123 studies identified, 11 were eligible for inclusion in the meta-analysis. The pooled mean birth weight, length, and head circumference in newborns whose mothers had UIC < 150 μg/L vs UIC ≥150 μg/L were 2898 g vs 2900 g (P = 0.970), 49.6 cm vs 49.4 cm (P = 0.880), and 34.0 cm vs 34.1 cm (P = 0.933), respectively. Dose-response meta-analyses revealed no significant linear or nonlinear associations between maternal UIC during pregnancy and anthropometric measures at birth. Among the different thyroid function parameters evaluated, high-normal values of maternal free thyroxine and thyrotropin during pregnancy were inversely associated with neonatal birth weight.

CONCLUSION

This systematic review showed that birth weight may be affected by even mild variations in the normal concentrations of maternal thyroid hormones. However, in the current meta-analysis, birth anthropometric measures were not associated with maternal UIC during pregnancy.

Is breast milk iodine concentration an influential factor in growth- and obesity-related hormones and infants' growth parameters?

Iodine, a key constituent of thyroid hormones, plays an indirect role in prenatal and postnatal growth. This study aimed to investigate whether breast milk iodine concentration (BMIC) is associated with growth- and obesity-related hormones and subsequently the infants' anthropometric measures. In present study conducted in Tehran (Iran), 94 lactating mothers and healthy infants who were exclusively breastfed were included. Concentrations of iodine, insulin-like growth factor-1 (IGF-1), adiponectin (AD) and leptin (LP) were measured in breast milk samples collected during 3- to 5-day postpartum. Anthropometric measures of infants were assessed at 6 months of life, and age- and sex-specific z-score values were calculated using the World Health Organization growth standards. The median (interquartile range) iodine, IGF-1, AD and LP concentrations were 232.5 (157.5-296.0) μg L-1 , 15.7 (11.9-21.1) ng ml-1 , 13.2 (5.1-29.8) mg L-1 and 1.16 (0.86-1.70) ng ml-1 in breast milk, respectively. No significant correlations were found between BMIC and IGF-1, AD and LP concentrations during the first few days postpartum. In adjusted regression model, BMIC was positively associated with weight-for-length z score of infants. In the presence of IGF-1, AD or LP, the coefficients of BMIC for weight-for-length z score of infants were β = .003 (P = .021), β = .002 (P = .028) or β = .003 (P = .013), respectively. No other anthropometric measurements were associated with iodine or growth- and obesity-related hormones in breast milk. Our findings indicate that BMIC is a potential contributor to infants' growth status, independent of IGF-1, AD or LP concentrations in breast milk. The underlying mechanisms remain to be elucidated.

[Factors associated with the nutritional status of iodine in the maternal-infant group: a systematic review]

This article sets out to identify the socio-demographic and nutritional factors associated with the nutritional status of iodine in the maternal-infant group. The review was based on the Prisma method and the Medline (PubMed), Scopus and Lilacs databases were consulted. The search was conducted in December 2018, using the key words nutritional status, iodine, infant, pregnant and lactating. The selection followed the stages of excluding duplicated articles, reading the titles, abstracts and texts in full. A total of 1,500 studies were identified and 26 met the inclusion criteria. The methodological quality of the studies was evaluated using the questionnaire proposed by Downs and Black. There was an association between the sociodemographic factors of income, education, maternal and gestational age, uniformity and place of residence in rural or urban areas with the nutritional state of iodine. In relation to dietary factors, the consumption of supplements, iodized salt and dietary sources of iodine, especially dairy products, play a protective role to avoid the deficiency. It is necessary to create more specific and effective strategies that address all the factors that affect the nutritional state of iodine to avoid the disorders resulting from the deficiency.

High national and sub-national coverage of iodised salt in India: evidence from the first National Iodine and Salt Intake Survey (NISI) 2014-2015

OBJECTIVE

The National Iodine and Salt Intake Survey (NISI) 2014-2015 was undertaken to estimate household iodised salt coverage at national and sub-national levels in India.

DESIGN

Cross-sectional survey with multistage stratified random sampling.

SETTING

India was divided into six geographic zones (South, West, Central, North, East and North-East) and each zone was further stratified into rural and urban areas to yield twelve distinct survey strata.

SUBJECTS

The target respondent from each household was selected as per predefined priority; wife of the household head, followed by women of reproductive age, followed by any adult available during the visit.

RESULTS

Households (n 5717) were surveyed and salt samples (n 5682) were analysed. Household coverage of iodised salt (iodine≥5 ppm) was 91·7 (95 % CI 91·0, 92·7) %. Adequately iodised salt (iodine≥15 ppm) was consumed in 77·5 (95 % CI 76·4, 78·6) % of households. Significant differences in coverage were seen across six geographic regions, with North and North-East zones on the verge of achieving the universal salt iodisation target of >90 % coverage. Coverage of households with adequately iodised salt (adjusted OR; 95 % CI) was significantly less in rural households (0·55; 0·47, 0·64), lower/backward castes (0·84; 0·72, 0·98), deprived households (0·72; 0·61, 0·85) as assessed by multidimensional poverty index, households with non-diverse diet (0·73; 0·62, 0·86) and households using non-packaged salt (0·48; 0·39, 0·59) and non-refined salt (0·17; 0·15, 0·20).

CONCLUSIONS

India is within striking reach of achieving universal salt iodisation. However, significant differentials by rural/urban, zonal and socio-economic indicators exist, warranting accelerated efforts and targeted interventions for high-risk groups.

Effects of Iodized Salt and Iodine Supplements on Prenatal and Postnatal Growth: A Systematic Review

Hypothyroidism due to iodine deficiency can impair physical development, most visibly in the marked stunting of myxedematous cretinism caused by severe in utero iodine deficiency. Whether iodine repletion improves growth in noncretinous children is uncertain. Therefore, the aim of our systematic review was to assess the effects of iodine fortification or supplementation on prenatal and postnatal growth outcomes in noncretinous children. Following Cochrane methods and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) reporting guidelines, we searched 10 databases including 2 Chinese databases (latest search February 2017). We included randomized and nonrandomized controlled trials (RCTs; non-RCTs), controlled before-after (CBA) studies, and interrupted time-series studies in pregnant women and children (≤18 y), which compared the effects of iodine (any form, dose, regimen) to placebo, noniodized salt, or no intervention on prenatal and postnatal growth outcomes. We calculated mean differences with 95% CIs, performed random-effects meta-analyses, and assessed the quality of evidence with the use of GRADE (Grading of Recommendations Assessment, Development and Evaluation). We included 18 studies (13 RCTs, 4 non-RCTs, 1 CBA) (n = 5729). Iodine supplementation of severely iodine-deficient pregnant women increased mean birthweight [mean difference (MD): 200 g; 95% CI: 183, 217 g; n = 635; 2 non-RCTs] compared to controls, but the quality of this evidence was assessed as very low. Iodine repletion across the other groups showed no effects on primary growth outcomes (quality of evidence mostly low and very low). Meta-analyses showed a positive effect in moderate-to-mildly iodine-deficient schoolchildren on insulin-like growth factor-1 (MD: 38.48 ng/mL; 95% CI: 6.19, 70.76 ng/mL; n = 498; 2 RCTs, low-quality evidence) and insulin-like growth factor binding protein-3 (MD: 0.46 μg/mL; 95% CI: 0.25, 0.66 μg/mL; n = 498; 2 RCTs, low-quality evidence). In conclusion, we identified few well-designed trials examining the effects of iodine repletion on growth. We are uncertain whether prenatal iodine repletion increases infant growth. Postnatal iodine repletion may improve growth factors but has no clear effects on somatic growth. Our systematic review was registered with PROSPERO as CRD42014012940.