The association of iron status with educational performance and intelligence among adolescents.

Dissanayake DS , Kumarasiri PV , Nugegoda DB , Dissanayake DM . Department of Community Medicine, Faculty of Medicine, University of Peradeniya Ceylon Med J. 2009

INTRODUCTION: The aim was to identify the association of iron status with educational performance and intelligence of adolescents. METHOD: This was a cross sectional comparative study among adolescents aged 13-15 years. Each iron deficient student was matched with an iron sufficient student from the same school, class and sex. Iron status was based on haemoglobin and serum ferritin levels. The marks for mathematics, science, Sinhala language and social science were considered to assess educational performance. Intelligence was measured by Raven's Standard progressive matrices. All the possible confounders and effect modifiers were considered. Home visits to a sub-sample checked the quality of data. RESULTS: The final analysis included 188 students (94 matched pairs). Neither educational performance nor intelligence showed significant associations with the iron status. The severity of the iron deficiency did not relate to these cognitive variables either. Twenty-three and 8 co-variables showed statistically significant associations with educational performance and intelligence respectively. Following a multiple regression analysis intelligence, the enthusiasm of the student towards learning, occupational ambition, household possession, problems at home and private tuition for mathematics were key factors predicting educational performance. Stunting and educational level of the mother were important factors influencing intelligence. CONCLUSION: Iron status does not play a major role in educational performance and intelligence of school going adolescents. Several factors affect educational performance and intelligence. This study highlights the difficulty in extrapolating the findings of similar studies to different ecological settings.

Iron deficiency and cognitive achievement among school-aged children and adolescents in the United States

Halterman JS , Kaczorowski JM , Aligne CA , Auinger P , Szilagyi PG . Department of Pediatrics, University of Rochester School of Medicine and Dentistry, NY, USA Pediatrics. 2001

CONTEXT: Iron deficiency anemia in infants can cause developmental problems. However, the relationship between iron status and cognitive achievement in older children is less clear. OBJECTIVE: To investigate the relationship between iron deficiency and cognitive test scores among a nationally representative sample of school-aged children and adolescents. DESIGN: The National Health and Nutrition Examination Survey III 1988-1994 provides cross-sectional data for children 6 to 16 years old and contains measures of iron status including transferrin saturation, free erythrocyte protoporphyrin, and serum ferritin. Children were considered iron-deficient if any 2 of these values were abnormal for age and gender, and standard hemoglobin values were used to detect anemia. Scores from standardized tests were compared for children with normal iron status, iron deficiency without anemia, and iron deficiency with anemia. Logistic regression was used to estimate the association of iron status and below average test scores, controlling for confounding factors. RESULTS: Among the 5398 children in the sample, 3% were iron-deficient. The prevalence of iron deficiency was highest among adolescent girls (8.7%). Average math scores were lower for children with iron deficiency with and without anemia, compared with children with normal iron status (86.4 and 87.4 vs 93.7). By logistic regression, children with iron deficiency had greater than twice the risk of scoring below average in math than did children with normal iron status (odds ratio: 2.3; 95% confidence interval: 1.1-4.4). This elevated risk was present even for iron-deficient children without anemia (odds ratio: 2.4; 95% confidence interval: 1.1-5.2). CONCLUSIONS: We demonstrated lower standardized math scores among iron-deficient school-aged children and adolescents, including those with iron deficiency without anemia. Screening for iron deficiency without anemia may be warranted for children at risk.

Food insecurity is associated with iron deficiency anemia in US adolescents

Eicher-Miller HA , Mason AC , Weaver CM , McCabe GP , Boushey CJ . Department of Foods and Nutrition and Statistics, Purdue University , West Lafayette , USA . Am J Clin Nutr. 2009

BACKGROUND: Food insecurity, a condition of low or very low food security, is associated with decreased nutrient intake and poor health, which can lead to nutrient deficiency in children, including iron deficiency and iron deficiency anemia. OBJECTIVE: The purpose of this study was to formally investigate the current relation of iron status and food security status among children aged 3-19 y (n = 11,247). DESIGN: Participants of the National Health and Nutrition Examination Survey 1999-2004 were classified for food security status by using the US Children's Food Security Scale and the US Household Food Security Scale. Iron deficiency was defined as > or =2 abnormal values for transferrin saturation, serum ferritin, and erythrocyte protoporphyrin, with the addition of abnormal hemoglobin to classify iron deficiency anemia. RESULTS: The odds of iron deficiency anemia among children aged 12-15 y were 2.95 times (95% CI: 1.18, 7.37; P = 0.02) those for children in households with food insecurity among children compared with children in households with food security among children. CONCLUSIONS: The results of this study indicate a continuing need for successful interventions to reduce iron deficiency anemia among food-insecure children and to improve food security among children

Unexplained decline in the prevalence of anemia among US children and women between 1988-1994 and 1999-2002

Cusick SE , Mei Z , Freedman DS , Looker AC , Ogden CL , Gunter E , Cogswell ME . US Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Division of Nutrition, Physical Activity, and Obesity, Atlanta , GA , USA . Am J Clin Nutr. 2008

BACKGROUND: The current anemia burden among US preschool children and women of childbearing age has not been documented. OBJECTIVE: We used data from National Health and Nutrition Examination Surveys 1988-1994 and 1999-2002 to examine recent anemia changes. DESIGN: We calculated the prevalence of anemia (hemoglobin < 11.0 g/dL at <24 mo, <11.1 g/dL at 24-59 mo, and <12.0 g/dL for women), iron deficiency anemia (anemia plus abnormal value >or=2: serum ferritin, transferrin saturation, and erythrocyte protoporphyrin), and high blood lead (>or=10 microg/dL) with anemia among children 12-59 mo and women 20-49 y in both surveys. Among women, we also calculated the prevalence of folate deficiency (erythrocyte folate < 317.2 nmol/L) with anemia and high C-reactive protein (>10 mg/L) with anemia. Multiple logistic regression was used to compare anemia prevalence between surveys, with control for race and age. RESULTS: Anemia declined significantly in children (from 8.0% to 3.6%; OR: 0.4; 95% CI: 0.3, 0.7) and women (10.8% to 6.9%; OR: 0.6; CI: 0.4, 0.7), but the prevalence of iron deficiency anemia did not change significantly in children (1.5% compared with 1.2%; OR: 0.7; 95% CI: 0.4, 1.5) or women (4.9% compared with 4.1%; OR: 0.8; 95% CI: 0.6, 1.1). Folate deficiency with anemia declined significantly in women (from 4.1% to 0.5%; OR: 0.1; 95% CI: 0.1, 0.2), but logistic regression models and standardization indicated that none of the known possible anemia causes could account for the decline in total anemia in children or women. CONCLUSIONS: The prevalence of anemia declined significantly among US women and children between 1988-1994 and 1999-2002, but this decline was not associated with changes in iron or folate deficiency, inflammation, or high blood lead.

The role of iron in neurocognitive development

Thomas DG , Grant SL , Aubuchon-Endsley NL . Department of Psychology, Oklahoma State University , Stillwater , Oklahoma USA Dev Neuropsychol. 2009

In this article we present a review of the current literature relating iron and iron deficiency to psychological and neurobiological outcomes in both humans and experimental animals. In particular, we focus on the role of iron during gestation and infancy and the possible impact on neurobehavioral development in the short and long term. In the context of reviewing this literature, the following questions are addressed: (1) What are the neural mechanisms that are directly influenced by iron and iron deficiency? (2) Does iron play a true causal role in determining these outcomes? (3) Is there a sensitive period during which iron deficiency is most harmful?

Iron deficiency and child development.

Lozoff B . Center for Human Growth and Development, Department of Pediatrics and Communicable Diseases, University of Michigan , USA . Food Nutr Bull. 2007

Iron deficiency is widespread in infants and young children, especially in developing countries. Animal models provide convincing evidence that, despite iron repletion, iron deficiency during the brain growth spurt alters metabolism and neurotransmission, myelination, and gene and protein profiles. In the human, there is compelling evidence that 6- to 24-month-old infants with iron-deficiency anemia are at risk for poorer cognitive, motor, social-emotional, and neurophysiologic development in the short- and long-term outcome. In contrast to inconsistent developmental effects of iron therapy for iron-deficient infants, recent large, randomized trials of iron supplementation in developing countries uniformly show benefits of iron, especially on motor development and social-emotional behavior. These results indicate that adverse effects can be prevented and/or reversed with iron earlier in development or before iron deficiency becomes severe or chronic. New findings also point to the need for more attention to the developmental effects of prenatal iron deficiency.

serum ferritin within the reference range a risk predictor of cardiovascular disease? A population-based, long-term study comprising 2874 subjects

Friedrich N , Milman N , Völzke H , Linneberg A , Jørgensen T . Institute for Community Medicine, Ernst Moritz Arndt University , Germany Br J Nutr. 2009

Nutrition and development: other micronutrients' effect on growth and cognition

Wasantwisut E . Institute of Nutrition , Mahidol University Salaya, Phutthamonthon, Nakhon Pathom , Thailand Southeast Asian J Trop Med Public Health. 1997

Previous studies have provided strong evidence that protein-energy malnutrition, deficiencies of iron and iodine early on in life led to compromised growth and cognitive functions in young children. Recently, a growing body of knowledge indicated that other micronutrients also play a role in young child development. Severe as well as marginal vitamin A efficiency were shown to lead to an increased risk of morbidity and mortality in children. A meta-analysis of vitamin A intervention trials indicated an overall reduction of 23% in all-cause mortality rate. Delayed growth, especially stunting, was reported in children with clinical signs of vitamin A deficiency. In addition, deficiency of zinc, which is essential for DNA and protein synthesis, leads to growth failure and delayed secondary sexual maturation in man and animals. Preterm infants appear to benefit from zinc administration in terms of growth and development. Supplementation studies in infants and older children revealed that those who manifested overt zinc deficiency through either clinical or biochemical indicators showed an improvement in linear growth and occasionally, an increase in weight gain. Zinc may also play a major role in brain function based on strong evidence from experimental animals. Zinc deficiency gestation in mice, rats, rhesus monkeys caused impaired learning, reduced attention and poor memory in their offspring. Data in humans are few and inconclusive. With respect to brain function alone, other nutrients such as docosahexaenoic acid (DHA, 22:6 n-3 fatty acid) improve visual acuity and mental development in small-for-gestational-age infants, folate supplementation during pregnancy prevents neural tube defect in infants, selenium deficiency in animals affects activities of brain enzymes necessary for brain development and function. Although evidence is accumulating that micronutrients other than iron and iodine may be important for physical growth and brain development in young children, more well-controlled studies in humans are needed. Critical issues to be considered include: single vs multiple limiting nutrients, critical period of deficiency, responsive indicators and variables that may affect the results as environmental, psychological and social factors.

Iron supplementation in early childhood: health benefits and risks

Iannotti LL , Tielsch JM , Black MM , Black RE . Department of International Health, Bloomberg School of Public Health , Johns Hopkins University , USA Am J Clin Nutr. 2006

The prevalence of iron deficiency among infants and young children living in developing countries is high. Because of its chemical properties--namely, its oxidative potential--iron functions in several biological systems that are crucial to human health. Iron, which is not easily eliminated from the body, can also cause harm through oxidative stress, interference with the absorption or metabolism of other nutrients, and suppression of critical enzymatic activities. We reviewed 26 randomized controlled trials of preventive, oral iron supplementation in young children (aged 0-59 mo) living in developing countries to ascertain the associated health benefits and risks. The outcomes investigated were anemia, development, growth, morbidity, and mortality. Initial hemoglobin concentrations and iron status were considered as effect modifiers, although few studies included such subgroup analyses. Among iron-deficient or anemic children, hemoglobin concentrations were improved with iron supplementation. Reductions in cognitive and motor development deficits were observed in iron-deficient or anemic children, particularly with longer-duration, lower-dose regimens. With iron supplementation, weight gains were adversely affected in iron-replete children; the effects on height were inconclusive. Most studies found no effect on morbidity, although few had sample sizes or study designs that were adequate for drawing conclusions. In a malaria-endemic population of Zanzibar , significant increases in serious adverse events were associated with iron supplementation, whereas, in Nepal , no effects on mortality in young children were found. More research is needed in populations affected by HIV and tuberculosis. Iron supplementation in preventive programs may need to be targeted through identification of iron-deficient children.

Iron deficiency in young children in low-income countries and new approaches for its prevention

Lutter CK . Pan American Health Organization, Washington , DC , USA . J Nutr. 2008

Anemia resulting from severe iron deficiency (ID) is the most prevalent and widespread nutrition-related health problem in infants and young children in low-income countries and has proven very resistant to prevention through public health interventions. Accumulative evidence from animal and human studies suggests that such deficiencies are associated with large adverse effects on child cognitive and motor development. Therefore, effective interventions to improve iron status will have large health benefits. Action to reduce young child ID would benefit from overarching policy and programmatic guidance that informs decision makers about what to do, when to do it, and how to do it. The impetus for new approaches to prevent ID in young children reflects growing recognition of the need to intervene early and often and for better vehicles to deliver iron. Prevention of ID requires strong delivery systems that enhance consumer demand and promote compliance. When this occurs, the prevalence of anemia is greatly reduced.