Iron Supplementation Benefits Physical Performance in Women of Reproductive Age: A Systematic Review and Meta-Analysis

Abstract

Animal and human observational studies suggest that iron deficiency impairs physical exercise performance, but findings from randomized trials on the effects of iron are equivocal. Iron deficiency and anemia are especially common in women of reproductive age (WRA). Clear evidence of benefit from iron supplementation would inform clinical and public health guidelines. Therefore, we performed a systematic review and meta-analysis to determine the effect of iron supplementation compared with control on exercise performance in WRA. We searched the Cochrane Central Register of Clinical Trials, MEDLINE, Scopus (comprising Embase and MEDLINE), WHO regional databases, and other sources in July 2013.Randomized controlled trials that measured exercise outcomes in WRA randomized to daily oral iron supplementation vs.control were eligible. Random-effects meta-analysis was used to calculate mean differences (MDs) and standardized MDs (SMDs). Risk of bias was assessed using the Cochrane risk-of-bias tool. Of 6757 titles screened, 24 eligible studies were identified, 22 of which contained extractable data. Only 3 studies were at overall low risk of bias. Iron supplementation improved both maximal exercise performance, demonstrated by an increase in maximal oxygen consumption (VO 2 max) [for relative VO 2 max, MD: 2.35 mL/(kg Á min); 95% CI: 0.82, 3.88; P = 0.003, 18 studies; for absolute VO 2 max, MD: 0.11 L/min; 95% CI: 0.03, 0.20; P = 0.01, 9 studies; for overall VO 2 max, SMD: 0.37; 95% CI: 0.11, 0.62; P = 0.005, 20 studies], and submaximal exercise performance, demonstrated by a lower heart rate (MD: 24.05 beats per minute; 95% CI: 27.25, 20.85; P = 0.01, 6 studies) and proportion of VO 2 max (MD: 22.68%; 95% CI: 24.94, 20.41; P = 0.02, 6 studies) required to achieve defined workloads. Daily iron supplementation significantly improves maximal and submaximal exercise performance in WRA, providing a rationale to prevent and treat iron deficiency in this group. This trial was registered with PROSPERO (http://www. crd.york.ac.uk/PROSPERO/prospero.asp) as CRD42013005166. J. Nutr. 144: 906-914, 2014.

Is iron treatment beneficial in, iron-deficient but non-anaemic (IDNA) endurance athletes? A systematic review and meta-analysis

“…The studies with the largest effect sizes had initial values <40 mL/kg/min24 27 28 compared to studies which showed no effect (>45 mL/kg/min), suggesting a greater potential for enhancement, particularly if the iron supplementation was combined with aerobic training. A recent meta-analysis investigating the effects of oral iron supplementation in women of reproductive age also reported significant effects on relative and absolute (increase of 2.35 mL/kg/min; 95% CI 0.82, 3.88 and 0.11 L/min; 95% CI 0.03 to 0.20, respectively) 54. Despite not being specific to iron deficiency or endurance athletes, this does support the suggestion that iron supplementation can enhance aerobic capacity.…”

Iron deficiency: new insights into diagnosis and treatment

“…However, the studies are small, heterogeneous in design, and not always unbiased. 32 Iron supplementation in very young preschool children living in low-income areas may correct anemia, but a large meta-analysis of randomized trials failed to find evidence of improved cognitive performance or positive effect on growth and development. 33 In endemic malarial areas iron supplementation raises the concern of increasing parasitemia or even clinical malaria.…”

Intervention of Floor Aerobics Exercise on Hematological Characteristics of People Living with HIV/AIDS, the Case of Yetessfa Bisrat Miskir Association, Dire Dawa, Ethiopia

“…Although the aerobic exercise improves the functional parameters of RA, its effects on the path physiology of the disease remain to be elucidated. The exercise, especially the aerobic subgroup, in healthy individuals result in increased total Hb concentration, HCT, and red blood cell (RBC) mass [42]. The aim of the current study is to investigate the effects of moderate aerobic exercise on the Hb, HCT, and RBC mass of women with RA.…”

“…The Australian National Physical Activity Guidelines for Adults recommend that for good health, "adults should put together at least 30 min of moderate intensity physical activity on most, preferably all, days." The aerobic exercise has been shown to be associated with increased RBC mass, Hb, and HCT in healthy individuals [42]. During the current study we tried to determine the effects of aerobic exercise on hematologic indices of women with RA.…”