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Evidence summaries

Iron Supplementation for Improving Prevalence of Anaemia and Iron Status in Menstruating Women

Daily or intermittent iron supplementation appears to be effective for reducing prevalence of anaemia and iron deficiency and raising haemoglobin and iron stores in menstruating women, but at the cost of gastrointestinal symptoms. Level of evidence: "B"

Summary

A Cochrane review [Abstract] 1 included 67 studies with a total of 8506 menstruating, non-pregnant women. At the end of intervention, women receiving iron compared with no iron were significantly less likely to be anaemic, had a reduced risk of iron deficiency, and had a higher haemoglobin concentration (table T1). Iron supplementation improved maximal and submaximal exercise performance, and appears to reduce symptomatic fatigue. Seven trials (n=901) reported on 'any side effect' and did not identify an overall increased prevalence of side effects from iron supplements (RR 2.14, 95% CI 0.94 to 4.86, low quality evidence) and 8 studies (n=1214) did not find any evidence of an increased prevalence of nausea. However, several studies identified an increased prevalence of gastrointestinal side effects, loose stools/diarrhoea, hard stools/constipation, or abdominal pain (table T2).

Table 1. Daily oral iron supplementation compared with no iron

Outcomes (at end of therapy)Relative effect(95% CI)Number of participants(studies)
AnaemiaRR 0.39 (0.25 to 0.60)3273 (10)
Haemoglobin , g/LMean Difference 5.30 (4.14 to 6.45)6861 (51)
Iron deficiencyRR 0.62 (0.50 to 0.76)1088 (7)

Table 2. Daily oral iron supplementation: Side effects

OutcomesRelative effect(95% CI)Number of participants(studies)
GI side effectsRR 1.99 (1.26 to 3.12)521 (5)
Loose stools/diarrhoeaRR 2.13 (1.10 to 4.11)604 (6 )
Hard stools/constipationRR 2.07 (1.35 to 3.17)1036 (8)
Abdominal painRR 1.55 (0.99 to 2.41)1190 (7)

Another Cochrane review [Abstract] 2 assessing the effects of intermittent oral iron supplementation included 25 studies with a total of 10 996 adolescent and adult menstruating women. Intermittent iron supplementation compared with no intervention or a placebo, reduced the risk of anaemia (RR 0.65, 95% CI 0.49 to 0.87; 11 studies, n=3135; low-quality evidence), and improved the concentration of haemoglobin (mean difference (MD) 5.19 g/L, 95% CI 3.07 to 7.32; 15 studies, n=2886; moderate-quality evidence). In comparison with daily supplementation, intermittent supplementation had similar effects on anaemia (RR 1.09, 95% CI 0.93 to 1.29; 8 studies, n=1749; moderate-quality evidence).

Clinical comments

Note

Date of latest search: 26 November 2020

    References

    • Low MS, Speedy J, Styles CE et al. Daily iron supplementation for improving anaemia, iron status and health in menstruating women. Cochrane Database Syst Rev 2016;(4):CD009747. [PubMed]
    • Fernández-Gaxiola AC, De-Regil LM. Intermittent iron supplementation for reducing anaemia and its associated impairments in adolescent and adult menstruating women. Cochrane Database Syst Rev 2019;(1):CD009218. [PubMed]

Primary/Secondary Keywords