Limited evidence suggested that iron supplementation produced a small improvement in cognitive development but had no effect on physical growth .
CONCLUSIONS : In 2 to 5 year olds , daily iron supplementation increases hemoglobin and ferritin .
There is a concerning lack of data on the effect of iron supplementation on clinical ly important outcomes including anemia , ID anemia , ID , and cognitive development .
BACKGROUND AND OBJECTIVES : Iron deficiency ( ID ) is the most common cause of anemia worldwide .
The prevalence is highest among preschool-aged children .
Iron is widely administered to children with or at risk for ID , but evidence of benefit among 2- to 5-year-old children has not been evaluated by systematic review .
We summarize the evidence for the benefit and safety of daily iron supplementation with regard to hematologic , growth , and cognitive parameters in 2 to 5 year olds .
Lack of hemoglobin response to iron supplementation in anemic mexican preschoolers with multiple micronutrient deficiencies.
BACKGROUND In developing countries , incomplete resolution of anemia with iron supplementation is often attributed to poor compliance or inadequate duration of supplementation , but it could result from deficiencies of other micronutrients . OBJECTIVE Our objective was to assess children 's hematologic  response to supervised , long-term iron supplementation and the relation of this response to other micronutrient deficiencies , anthropometry , morbidity , and usual dietary intake . DESIGN Rural Mexican children aged 18 - 36 mo ( n = 219 ) were supplemented for 12 mo with either 20 mg Fe , 20 mg Zn , both iron and zinc , or placebo . Children were categorized as iron-unsupplemented ( IUS ; n = 109 ) or iron supplemented ( IS ; n = 108 ) . Hemoglobin , hematocrit , mean corpuscular volume , mean cell hemoglobin , plasma concentrations of micronutrients that can affect hematopoiesis , anthropometry , and diet were assessed at 0 , 6 , and 12 mo ; morbidity was assessed biweekly . RESULTS At baseline , 70 % of children had low hemoglobin ( < /=115 g/L ) , 60 % had low hematocrit , 48 % were ferritin deficient , 10 % had deficient and 33 % had low plasma vitamin B-12 concentrations , 29 % had deficient vitamin A concentrations , and 70 % had deficient vitamin E concentrations . Iron supplementation increased ferritin from 11 + /- 14 microg/L at baseline to 31 + /- 18 microg/L after 6 mo ( P < 0.001 ) and 41 + /- 17 microg/L after 12 mo . However , anemia persisted in 30 % and 31 % of supplemented children at 6 and 12 mo , respectively , and was not significantly different between the IUS and IS groups at 12 mo . Initial plasma vitamin B-12 , height-for-age , and dietary quality predicted the hematopoietic response to iron . CONCLUSION Lack of hemoglobin response to iron was associated with indicators of chronic undernutrition and multiple micronutrient deficiencies
Limited evidence suggested that iron supplementation produced a small improvement in cognitive development but had no effect on physical growth .
CONCLUSIONS : In 2 to 5 year olds , daily iron supplementation increases hemoglobin and ferritin .
There is a concerning lack of data on the effect of iron supplementation on clinical ly important outcomes including anemia , ID anemia , ID , and cognitive development .
BACKGROUND AND OBJECTIVES : Iron deficiency ( ID ) is the most common cause of anemia worldwide .
The prevalence is highest among preschool-aged children .
Iron is widely administered to children with or at risk for ID , but evidence of benefit among 2- to 5-year-old children has not been evaluated by systematic review .
We summarize the evidence for the benefit and safety of daily iron supplementation with regard to hematologic , growth , and cognitive parameters in 2 to 5 year olds .