“An Integrated Infant and Young Child Feeding and Small-Quantity Lipid-based Nutrient Supplementation Program Is Associated With Improved Gross Motor and Communication Scores of Children 6-18 Months in the Democratic Republic of Congo”, Addo et al 2020

2020-addo.pdf: “An Integrated Infant and Young Child Feeding and Small-Quantity Lipid-based Nutrient Supplementation Program Is Associated with Improved Gross Motor and Communication Scores of Children 6-18 Months in the Democratic Republic of Congo”⁠, O. Yaw Addo, Katie Tripp, Simeon Nanama, Bope Albert, Fanny Sandalinas, Ambroise Nanema, Maria Elena Jefferds, et al (2020-02-28)

“Cognitive Consequences Of Iodine Deficiency In Adolescence: Evidence From Salt Iodization In Denmark”, Serena 2019

“Cognitive Consequences Of Iodine Deficiency In Adolescence: Evidence From Salt Iodization In Denmark”⁠, Benjamin Ly Serena (2019-06-21; backlinks):

Over the past three decades, many countries have introduced iodized salt policies to eradicate iodine deficiency. While it is well known that iodine deficiency in utero is detrimental to cognitive ability, little is known about the consequences of iodine deficiencies after birth.

This paper examines the impact of iodine deficiency in adolescence on cognitive performance. I identify the causal effect of iodine deficiency quasi-experimentally using the introduction of iodized salt in Denmark. Denmark went from a ban on iodized salt before 1998 to a mandate after 2001, making it an ideal national experiment.

Combining administrative records on high school grades over a 30-year period with geographic variation in initial iodine deficiency, I find that salt iodization increases the Grade Point Averages of high school students by 6–9 percent of a standard deviation. This improvement is comparable to the benefits of more standard school achievement policies and at much lower costs.

[Keywords: iodine deficiency, iodized salt, nutrition, human capital, health]

“Effect of Iodine Supplementation in Pregnant Women on Child Neurodevelopment: a Randomised, Double-blind, Placebo-controlled Trial”, Gowachirapant et al 2017

2017-gowachirapant.pdf: “Effect of iodine supplementation in pregnant women on child neurodevelopment: a randomised, double-blind, placebo-controlled trial”⁠, Sueppong Gowachirapant, Nidhi Jaiswal, Alida Melse-Boonstra, Valeria Galetti, Sara Stinca, Ian Mackenzie, et al (2017-11-01)

“Iodine Supplementation for Premature Infants Does Not Improve IQ”, N. 2017

2017-pearce.pdf: “Iodine Supplementation for Premature Infants Does Not Improve IQ”⁠, Pearce Elizabeth N. (2017-01-01; backlinks)

“Small-quantity, Lipid-based Nutrient Supplements Provided to Women during Pregnancy and 6 Mo Postpartum and to Their Infants from 6 Mo of Age Increase the Mean Attained Length of 18-mo-old Children in Semi-urban Ghana: a Randomized Controlled Trial”, Adu-Afarwuah et al 2016

“Small-quantity, lipid-based nutrient supplements provided to women during pregnancy and 6 mo postpartum and to their infants from 6 mo of age increase the mean attained length of 18-mo-old children in semi-urban Ghana: a randomized controlled trial”⁠, Seth Adu-Afarwuah, Anna Lartey, Harriet Okronipa, Per Ashorn, Janet M. Peerson, Mary Arimond, Ulla Ashorn, et al (2016; backlinks):

Background: Childhood stunting usually begins in utero and continues after birth; therefore, its reduction must involve actions across different stages of early life.

Objective: We evaluated the efficacy of small-quantity, lipid-based nutrient supplements (SQ-LNSs) provided during pregnancy, lactation, and infancy on attained size by 18 mo of age.

Design: In this partially double-blind, individually randomized trial, 1320 women at ≤20 wk of gestation received standard iron and folic acid (IFA group), multiple micronutrients (MMN group), or SQ-LNS (LNS group) daily until delivery, and then placebo, MMNs, or SQ-LNS, respectively, for 6 mo postpartum; infants in the LNS group received SQ-LNS formulated for infants from 6 to 18 mo of age (endline). The primary outcome was child length by 18 mo of age.

Results: At endline, data were available for 85% of 1228 infants enrolled; overall mean length and length-for-age z score (LAZ) were 79.3 cm and -0.83, respectively, and 12% of the children were stunted (LAZ <-2). In analysis based on the intended treatment, mean ± SD length and LAZ for the LNS group (79.7 ± 2.9 cm and -0.69 ± 1.01, respectively) were significantly greater than for the IFA (79.1 ± 2.9 cm and -0.87 ± 0.99) and MMN (79.1 ± 2.9 cm and -0.91 ± 1.01) groups (p = 0.006 and p = 0.009, respectively). Differences were also significant for weight and weight-for-age z score but not head or midupper arm circumference, and the prevalence of stunting in the LNS group was 8.9%, compared with 13.7% in the IFA group and 12.9% in the MMN group (p = 0.12). In analysis based on actual supplement provided at enrollment, stunting prevalences were 8.9% compared with 15.1% and 11.5%, respectively (p = 0.045).

Conclusion: Provision of SQ-LNSs to women from pregnancy to 6 mo postpartum and to their infants from 6 to 18 mo of age may increase the child’s attained length by age 18 mo in similar settings. This trial was registered at clinicaltrials.gov as NCT00970866.

“The Effects of the Generalized Use of Iodized Salt on Occupational Patterns in Switzerland”, Politi 2015

2015-politi.pdf: “The effects of the generalized use of iodized salt on occupational patterns in Switzerland”⁠, Dimitra Politi (2015-12-15; backlinks):

I estimate the long-term impact of the first large-scale nutritional supplementation program, salt iodization, which took place in Switzerland in the 1920s and 1930s. Iodized salt improved the health environment in utero, and it eradicated mental retardation caused by insufficient iodine intake. By exploiting variation in the pre-existing prevalence of iodine deficiency, as well as differences in the timing of the intervention across Swiss cantons, I show that cohorts born in previously highly deficient areas after the introduction of iodized salt were more likely to enter top-tier occupations with higher cognitive demands. As a result, wages of these cohorts were higher, accounting for about 1.9% of annual median earnings, or 2% of Swiss GDP per capita in 1991.

[Keywords: Iodine deficiency, cognitive ability, occupational choice, human capital, productivity]

“Ironing Out Deficiencies: Evidence from the United States on the Economic Effects of Iron Deficiency”, Niemesh 2015

2015-niemesh.pdf: “Ironing Out Deficiencies: Evidence from the United States on the Economic Effects of Iron Deficiency”⁠, Gregory T. Niemesh (2015-09-01; economics; backlinks):

Iron deficiency reduces productive capacity in adults and impairs cognitive development in children. In 1943, the United States government required the fortification of bread with iron to reduce iron deficiency in the working-age population during World War II.

This nationwide fortification of grain products increased per capita consumption of iron by 16%. I find that areas with lower levels of iron consumption prior to the mandate experienced greater increases in income and school enrollment in the 1940s. A long-term followup suggests that adults in 1970 with more exposure to fortification during childhood earned higher wages.

“Costs and Benefits of Iodine Supplementation for Pregnant Women in a Mildly to Moderately Iodine-deficient Population: a Modelling Analysis”, Monahan et al 2015

2015-monahan.pdf: “Costs and benefits of iodine supplementation for pregnant women in a mildly to moderately iodine-deficient population: a modelling analysis”⁠, Mark Monahan, Kristien Boelaert, Kate Jolly, Shiao Chan, Pelham Barton, Tracy E. Roberts (2015-08-10; iq /​ ​ses; backlinks):

Background: Results from previous studies show that the cognitive ability of offspring might be irreversibly damaged as a result of their mother’s mild iodine deficiency during pregnancy. A reduced intelligence quotient (IQ) score has broad economic and societal cost implications because intelligence affects wellbeing, income, and education outcomes. Although pregnancy and lactation lead to increased iodine needs, no UK recommendations for iodine supplementation have been issued to pregnant women. We aimed to investigate the cost-effectiveness of iodine supplementation versus no supplementation for pregnant women in a mildly to moderately iodine-deficient population for which a population-based iodine supplementation programme—for example, universal salt iodisation—did not exist.

Methods: We systematically searched MEDLINE, Embase, EconLit, and NHS EED for economic studies that linked IQ and income published in all languages until Aug 21, 2014. We took clinical data relating to iodine deficiency in pregnant women and the effect on IQ in their children aged 8–9 years from primary research. A decision tree was developed to compare the treatment strategies of iodine supplementation in tablet form with no iodine supplementation for pregnant women in the UK. Analyses were done from a health service perspective (analysis 1; taking direct health service costs into account) and societal perspective (analysis 2; taking education costs and the value of an IQ point itself into account), and presented in terms of cost (in sterling, relevant to 2013) per IQ point gained in the offspring. We made data-supported assumptions to complete these analyses, but used a conservative approach that limited the benefits of iodine supplementation and overestimated its potential harms.

Findings: Our systematic search identified 1361 published articles, of which eight were assessed to calculate the monetary value of an IQ point. A discounted lifetime value of an additional IQ point based on earnings was estimated to be £3297 (study estimates range from £1319 to £11 967) for the offspring cohort. Iodine supplementation was cost saving from both a health service perspective (saving £199 per pregnant woman [sensitivity analysis range –£42 to £229]) and societal perspective (saving £4476 per pregnant woman [sensitivity analysis range £540 to £4495]), with a net gain of 1·22 IQ points in each analysis. Base case results were robust to sensitivity analyses.

Interpretation: Iodine supplementation for pregnant women in the UK is potentially cost saving. This finding also has implications for the 1·88 billion people in the 32 countries with iodine deficiency worldwide. Valuation of IQ points should consider non-earnings benefits—eg, health benefits associated with a higher IQ not germane to earnings.

“Iodine Deficiency and Thyroid Disorders”, Zimmermann & Boelaert 2015

2015-zimmerman.pdf: “Iodine deficiency and thyroid disorders”⁠, Michael B. Zimmermann, Kristien Boelaert (2015-01-01)

“The Impact of Iodine Deficiency Eradication on Schooling: Evidence from the Introduction of Iodized Salt in Switzerland”, Politi 2014

2014-politi.pdf: “The Impact of Iodine Deficiency Eradication on Schooling: Evidence from the Introduction of Iodized Salt in Switzerland”⁠, Dimitra Politi (2014-05-09; backlinks):

I study the impact of salt iodization in Switzerland on graduation rates. The programme, which began in 1922 and continues to this day, was the first wide-reaching nutritional intervention ever to take place. Iodine deficiency in utero causes mental retardation, and correcting the deficiency is expected to increase the productivity of a population by increasing its cognitive ability. The exogenous increase in cognitive ability brought about by the iodization program is also useful in the context of disentangling the effects of innate ability and education on later-life outcomes. I identify the impact of iodization on graduation rates by exploiting pre-existing geographic variation in the prevalence of iodine deficiency, as well as spatial and temporal variation in the introduction of iodized salt across Swiss cantons. By looking at sharp, discontinuous increases in iodized salt circulation I show that the eradication of iodine deficiency in previously deficient areas statistically-significantly increased graduation rates from upper secondary and tertiary education. My results are robust to falsification tests and different measures of iodine deficiency.

[Keywords: Cognitive ability, education, human capital, productivity]

“Characteristics of IQ of 293 School-aged Children”, Huang & Yang 2013

2013-huang.pdf: “Characteristics of IQ of 293 school-aged children”⁠, Min-ning Huang, Gui-feng Yang (2013-03-26)

“Is Working Memory Training Effective? A Meta-Analytic Review”, Melby-Lervåg & Hulme 2013

“Is Working Memory Training Effective? A Meta-Analytic Review”⁠, Monica Melby-Lervåg, Charles Hulme (2013-02; dual-n-back; backlinks):

It has been suggested that working memory training programs are effective both as treatments for attention-deficit/​​hyperactivity disorder (ADHD) and other cognitive disorders in children and as a tool to improve cognitive ability and scholastic attainment in typically developing children and adults. However, effects across studies appear to be variable, and a systematic meta-analytic review was undertaken. To be included in the review, studies had to be randomized controlled trials or quasi-experiments without randomization, have a treatment, and have either a treated group or an untreated control group.

23 studies with 30 group comparisons met the criteria for inclusion. The studies included involved clinical samples and samples of typically developing children and adults. Meta-analyses indicated that the programs produced reliable short-term improvements in working memory skills. For verbal working memory, these near-transfer effects were not sustained at follow-up, whereas for visuospatial working memory, limited evidence suggested that such effects might be maintained. More importantly, there was no convincing evidence of the generalization of working memory training to other skills (nonverbal and verbal ability, inhibitory processes in attention, word decoding, and arithmetic).

The authors conclude that memory training programs appear to produce short-term, specific training effects that do not generalize. Possible limitations of the review (including age differences in the samples and the variety of different clinical conditions included) are noted. However, current findings cast doubt on both the clinical relevance of working memory training programs and their utility as methods of enhancing cognitive functioning in typically developing children and healthy adults.

[Keywords: working memory training, ADHD, attention, learning disabilities]

“Mild Iodine Deficiency in Pregnancy in Europe and Its Consequences for Cognitive and Psychomotor Development of Children: A Review”, Trumpff et al 2013

2013-trumpff.pdf: “Mild iodine deficiency in pregnancy in Europe and its consequences for cognitive and psychomotor development of children: A review”⁠, Caroline Trumpff, Jean De Schepper, Jean Tafforeau, Herman Van Oyen, Johan Vanderfaeillie, Stefanie Vandevijvere, et al (2013-01-01; backlinks)

“The Cognitive Effects of Micronutrient Deficiency: Evidence from Salt Iodization in the United States”, Feyrer et al 2013

2013-feyrer.pdf: “The Cognitive Effects of Micronutrient Deficiency: Evidence from Salt Iodization in the United States”⁠, James Feyrer, Dimitra Politi, David N. Weil (2013-01-01; backlinks)

“The Impact of Iodine Supplementation and Bread Fortification on Urinary Iodine Concentrations in a Mildly Iodine Deficient Population of Pregnant Women in South Australia”, Clifton et al 2013

“The impact of iodine supplementation and bread fortification on urinary iodine concentrations in a mildly iodine deficient population of pregnant women in South Australia”⁠, Vicki L. Clifton, Nicolette A. Hodyl, Paul A. Fogarty, David J. Torpy, Rachel Roberts, Ted Nettelbeck, et al (2013; backlinks):

Mild iodine deficiency during pregnancy can have statistically-significant effects on fetal development and future cognitive function. The purpose of this study was to characterise the iodine status of South Australian women during pregnancy and relate it to the use of iodine-containing multivitamins. The impact of fortification of bread with iodized salt was also assessed. Women (n = 196) were recruited prospectively at the beginning of pregnancy and urine collected at 12, 18, 30, 36 weeks gestation and 6 months postpartum. The use of a multivitamin supplement was recorded at each visit. Spot urinary iodine concentrations (UIC) were assessed. Median UICs were within the mildly deficient range in women not taking supplements (<90 μg/​​L). Among the women taking iodine-containing multivitamins UICs were within WHO recommendations (150–249 μg/​​L) for sufficiency and showed an increasing trend through gestation. The fortification of bread with iodized salt increased the median UIC from 68 μg/​​L to 84 μg/​​L (p = .011) which was still in the deficient range. Pregnant women in this region of Australia were unlikely to reach recommended iodine levels without an iodine supplement, even after the mandatory iodine supplementation of bread was instituted in October 2009.

“Wechsler Intelligence Scale for Children Testing among Chinese Children With Learning Difficulties: a Meta-analysis”, Tong et al 2012

2012-tong.pdf: “Wechsler Intelligence Scale for Children testing among Chinese children with learning difficulties: a meta-analysis”⁠, Fang Tong, Tong Fu, Jing Sun (2012-09-01)

“Iodine Intake in Human Nutrition: a Systematic Literature Review”, Gunnarsdottir & Dahl 2012

“Iodine intake in human nutrition: a systematic literature review”⁠, Ingibjörg Gunnarsdottir, Lisbeth Dahl (2012; backlinks):

The present literature review is a part of the NNR5 project with the aim of reviewing and updating the scientific basis of the 4^th edition of the Nordic Nutrition Recommendations (NNR) issued in 2004. The main objective of the review is to assess the influence of different intakes of iodine at different life stages (infants, children, adolescents, adults, elderly, and during pregnancy and lactation) in order to estimate the requirement for adequate growth, development, and maintenance of health. The literature search resulted in 1,504 abstracts. Out of those, 168 papers were identified as potentially relevant. Full paper selection resulted in 40 papers that were quality assessed (A, B, or C). The grade of evidence was classified as convincing, probable, suggestive, and no conclusion. We found suggestive evidence for improved maternal iodine status and thyroid function by iodine supplementation during pregnancy. Suggestive evidence was found for the relationship between improved thyroid function (used as an indicator of iodine status) during pregnancy and cognitive function in the offspring up to 18 months of age. Moderately to severely iodine-deficient children will probably benefit from iodine supplementation or improved iodine status in order to improve their cognitive function, while only one study showed improved cognitive function following iodine supplementation in children from a mildly iodine-deficient area (no conclusion). No conclusions can be drawn related to other outcomes included in our review. There are no new data supporting changes in dietary reference values for children or adults. The rationale for increasing the dietary reference values for pregnant and lactating women in the NNR5 needs to be discussed in a broader perspective, taking iodine status of pregnant women in the Nordic countries into account.

“Analysis of Intelligence Quotient of School Children Surveyed in Dalian City of Liaoning Province during 2006 to 2009”, Yao et al 2011

2011-yao.pdf: “Analysis of intelligence quotient of school children surveyed in Dalian city of Liaoning province during 2006 to 2009”⁠, Wei Yao, Bing Zhang, Shi-liang Shao, Dan mei, Feng-yi Chen (2011-05-20)

“Analysis on Iodine Nutritional Status and Intelligent Development of Children Aged 8-10 in Coastal Salt-producing Areas and Coastal Non-salt-producing Areas”, Wu et al 2011

2011-wu.pdf: “Analysis on iodine nutritional status and intelligent development of children aged 8-10 in coastal salt-producing areas and coastal non-salt-producing areas”⁠, Xiao-qing Wu, Long Dai, Ya-ping Zhang, Jian-jun Niu, Min Chen, Tian-chang Kang, Zhi-min Qiu, Jin-lian Ke, et al (2011-04-15)

“Iodine Deficiency Disorders After a Decade of Universal Salt Iodization in a Severe Iodine Deficiency Region in China”, Wang et al 2009

2009-wang.pdf: “Iodine deficiency disorders after a decade of universal salt iodization in a severe iodine deficiency region in China”⁠, Yanling Wang, Zhongliang Zhang, Pengfei Ge, Yibo Wang, Shigong Wang (2009-10-01)

“Delayed Neurobehavioral Development in Children Born to Pregnant Women With Mild Hypothyroxinemia During the First Month of Gestation: The Importance of Early Iodine Supplementation”, Berbel et al 2009

2009-berbel.pdf: “Delayed Neurobehavioral Development in Children Born to Pregnant Women with Mild Hypothyroxinemia During the First Month of Gestation: The Importance of Early Iodine Supplementation”⁠, Pere Berbel, José Luis Mestre, Asunción Santamaría, Inmaculada Palazón, Ascensión Franco, Marisa Graells, et al (2009-01-01; backlinks)

“Surveillance on Iodine Deficiency Disorders in China in 2005: an Analysis of Intelligence Test”, Li et al 2006

2006-li.pdf: “Surveillance on iodine deficiency disorders in China in 2005: an analysis of intelligence test”⁠, Ying Li, Dong Wang, Xiao-hui Su, Shu-bin Zhang, Jun Yu (2006-07-20)

“IQ in the Ramsey Model: A Naïve Calibration”, Jones 2006

“IQ in the Ramsey Model: A Naïve Calibration”⁠, Garett Jones (2006; iq /​ ​ses; backlinks):

I show that in a conventional Ramsey model, between one-fourth and one-half of the global income distribution can be explained by a single factor: The effect of large, persistent differences in national average IQ on the private marginal product of labor. Thus, differences in national average IQ may be a driving force behind global income inequality. These persistent differences in cognitive ability—which are well-supported in the psychology literature—are likely to be somewhat malleable through better health care, better education, and especially better nutrition in the world’s poorest countries. A simple calibration exercise in the spirit of Bils and Klenow (2000) and Castro (2005) is conducted. I show that an IQ-augmented Ramsey model can explain more than half of the empirical relationship between national average IQ and GDP per worker. I provide evidence that little of the IQ-productivity relationship is likely to be due to reverse causality.

“Dietary Iodine in Pregnant Women from the Boston, Massachusetts Area”, Pearce et al 2004

2004-pearce.pdf: “Dietary Iodine in Pregnant Women from the Boston, Massachusetts Area”⁠, Elizabeth N. Pearce, Hamid R. Bazrafshan, Xuemei He, Sam Pino, Lewis E. Braverman (2004-01-01; backlinks)

“Economic Status and Health in Childhood: The Origins of the Gradient”, Case et al 2002

2002-case.pdf: “Economic Status and Health in Childhood: The Origins of the Gradient”⁠, Anne Case, Darren Lubotsky, Christina Paxson (2002-12-01; backlinks):

The well-known positive association between health and income in adulthood has antecedents in childhood. Not only is children’s health positively related to household income, but the relationship between household income and children’s health becomes more pronounced as children age. Part of the relationship can be explained by the arrival and impact of chronic conditions. Children from lower-income households with chronic conditions have worse health than do those from higher-income households. The adverse health effects of lower income accumulate over children’s lives. Part of the intergenerational transmission of socioeconomic status may work through the impact of parents’ income on children’s health.

“Iodised Salt for Preventing Iodine Deficiency Disorders”, T et al 2002

2002-wu.pdf: “Iodised salt for preventing iodine deficiency disorders”⁠, Wu T, Liu GJ, Li P, Clar C (2002-01-01; backlinks)

“9757 Van Stuijvenberg”, David 1999

1999-vanstuijvenberg.pdf: “9757 van Stuijvenberg”⁠, David (1999-01-01; backlinks)

“Dietary Intake and Micronutrient Status of Adolescents: Effect of Vitamin and Trace Element Supplementation on Indices of Status and Performance in Tests of Verbal and Non-verbal Intelligence”, Southon et al 1994

1994-southon.pdf: “Dietary intake and micronutrient status of adolescents: effect of vitamin and trace element supplementation on indices of status and performance in tests of verbal and non-verbal intelligence”⁠, Susan Southon, A. J. A. Wright, P. M. Finglas, Angela L. Bailey, Julie M. Loughridge, A. D. Walker (1994-01-01; backlinks)

“Impairment of Mental Development by Iodine Deficiency and Its Correction. A Retrospective View of Studies in Peru”, Pretell & Caceres 1994

1994-pretell.pdf: “Impairment of mental development by iodine deficiency and its correction. A retrospective view of studies in Peru”⁠, Eduardo A. Pretell, Artidoro Caceres (1994-01-01; backlinks)

“Prophylaxis and Treatment of Endemic Goiter With Iodized Oil in Rural Ecuador and Peru”, Kevany et al 1969

1969-kevany.pdf: “Prophylaxis and Treatment of Endemic Goiter with Iodized Oil in Rural Ecuador and Peru”⁠, John Kevany, Rodrigo Fierro-Benitez, Eduardo A. Pretell, John B. Stanbury (1969-12-01; backlinks):

Endemic goiter continues to be a substantial health problem in many areas of the world. In some areas the disease is so severe that cretinism and other associated defects are found. In many areas, geographic, economic, and other factors prevent the use of iodized salt as a preventive measure.

A pilot program using iodized poppy seed oil has been instituted in two rural communities in Ecuador and three in Peru. Results after approximately 2 years indicate the feasibility and effectiveness of the programs. There has been a sharp reduction in the incidence of goiter. Cretinism has not yet appeared among the progeny of the population injected with iodized oil, but several instances have appeared in control groups. The use of iodized oil as a public health procedure for the prevention of endemic goiter and its associated defects is an acceptable measure in regions where salt-iodization programs cannot be presently undertaken.