ABSTRACT
Objectives: 47% of pre-school children and 25% of school-aged children are anaemic. Daily iron supplementation remains a key anaemia control intervention, but benefits and safety in children are debated. We systematically reviewed evidence for daily iron supplementation in 4–23m, 2-5y and 5-12y children. Methods: Separate searches and systematic-reviews/meta-analyses were performed for each age-group. Electronic databases and other sources were searched for randomized controlled trials comparing daily iron supplementation with control. Random-effects meta-analysis was used. Risk-of-bias was estimated using the Cochrane tool. Results: For children 4-23m, 2-5y and 5-12y respectively we identified 9533, 9169 and 16501 citations, from which 35, 15 and 32 eligible studies were identified, of which 9, 0 and 4 were at low overall risk-of-bias. Iron improved haemoglobin and ferritin and, in 4-23 m and 5-12y, reduced anaemia and iron deficiency. In 5-12y, iron improved global cognitive scores (SMD 0.50 [0.11, 0.90], p = 0.01) and in anaemic children, IQ (MD 4.55 [0.16, 8.94], p = 0.04). In 2-5y, limited data suggested a small improvement from iron in cognitive performance. No benefit was evident in 4-23 m (Bayley’s mental development index: MD 1·65 [–0·63, 3·94]) overall but was seen in iron deficient children (MD 5.90 [1.91, 10.00], p=0.005). Iron did not benefit growth in 4-23 m or 2-5y, but did improve growth in 5-12y. Vomiting and fever were increased in 4-23m receiving iron. Conclusions: Although supplementation iron improves cognition in older children or children with ID, evidence of non-haematologic benefit in pre-school children is inadequate. Further research is needed to enable guideline development.
ABSTRACT
Objectives: Animal and human observational studies suggest iron deficiency impairs physical exercise performance but findings from randomized trials are conflicting. Iron deficiency and anaemia are especially common in women of reproductive age (WRA). We therefore performed a systematic review and meta-analysis to determine the effect of iron supplementation on exercise performance in WRA. Methods: We searched the Cochrane Central Register of Clinical Trials, MEDLINE, Scopus (comprising Embase and MEDLINE), WHO regional databases and other sources in July 2013. Randomised controlled trials that measured exercise outcomes in WRA randomized to daily oral iron supplementation versus control were eligible. Random-effects meta-analysis was used to calculate Mean Differences (MD) and Standardised MDs (SMD). Risk of bias was assessed using the Cochrane risk-of-bias tool. Results: Of 6757 titles screened, 22 eligible studies contained extractable data. Only 3 were at overall low risk of bias. Iron supplementation improved both maximal exercise performance, demonstrated by an increase in VO2 max (relative VO2 max: MD 2.35 mL/kg/min [95% CI 0.82, 3.88], P=0.003, 18 studies; absolute VO2 max: MD 0.11 L/min [0.03, 0.20], P=0.01, 9 studies; overall VO2 max: SMD 0.37 [0.11, 0.62] P=0.005, 20 studies), and submaximal exercise performance demonstrated by a lower heart rate (MD -4.05 beats per minute [-7.25, -0.85], P=0.01, 6 studies) and proportion of VO2 max (MD -2.68% [-4.94, -0.41], P=0.02, 6 studies) required to achieve defined workloads. Conclusions: Daily iron supplementation improves maximal and submaximal exercise performance in WRA, providing a rationale to prevent and treat iron deficiency in this group.