Effect of iron supplementation on physical performance in children and adolescents: systematic review of randomized controlled trials

Abstract

Objective: To evaluate the effect of iron supplementation on physical performance in children (0-18 years) through systematic review of randomised controlled trials (RCTs).

Data sources: Electronic databases, personal files, handsearch of reviews, bibliographies of books, abstracts and proceedings of international conferences.

Review methods: RCTs with interventions that included oral or parenteral iron supplementation, fortified formula milk, or cereals were evaluated. The physical performance outcomes studied were heart rate, treadmill endurance times, blood lactate, and oxygen consumption.

Results: A total of three studies were included, in all of which iron was supplemented in the form of oral medicinal iron. At 5, 6 and 7 miles per hour running speeds, the pooled weighted mean (95% Cl) difference (WMD) in the heart rate (per minute) between the iron and the placebo, following exercise was -7.3 (-19.6, 4.9; p = 0.241), -6.6 (- 19.9, 6.6; p = 0.327), and -8.0 (-19.7, 3.7; p = 0.182), respectively. After excluding the study with nonanemic subjects, the corresponding figures were -13.1 (-23.2, -3.1; p= 0.01), -14.2 (-22.3, -6.1; p = 0.001) and -12.7 (-23.5, 1.9; p = 0.021), respectively. Oxygen consumption, estimated in two studies, showed no significant difference between the treatment groups. Blood lactate levels were estimated in one study only at two different doses of iron, and were significantly lower (p < 0.05) in iron supplemented group in comparison to placebo both before (7.71 and 7.55 mg/dL versus 8.43 mg/dL) and after (14.36 and 14.35 mg/dL versus 16.48 mg/dL) exercise. Treadmill endurance time was significantly better in iron supplemented group when compared with placebo in one study.

Conclusions: Iron supplementation may have a positive effect on the physical performance of children, as evaluated through the post exercise heart rate in anemic subjects, blood lactate levels and treadmill endurance time. In view of the limited data availability, this finding cannot be considered conclusive.