This updated Cochrane Intervention Review assessed the effects of intermittent oral iron supplementation, alone or in combination with other nutrients, on anaemia and its associated impairments among menstruating women, compared with no intervention, placebo, or daily supplementation.
The review included 25 studies involving 10,996 women. Most studies were implemented in school settings and funded by international organisations, universities, and ministries of health within the countries. Approximately one third of the included studies did not provide a funding source. The main limitations of the studies were lack of blinding and high attrition.
The evidence suggested that, among menstruating women, intermittent oral supplementation with iron (alone plus any other nutrients) increased haemoglobin and ferritin concentrations and reduced the prevalence of anaemia compared to no supplementation or placebo. Furthermore, these findings were not affected by whether the supplements were given once or twice weekly, for less or more than three months, contained less or more than 60 mg of elemental iron per weeks, or given to populations with different degrees of anaemia at baseline. There was also evidence that, compared with daily supplementation, intermittent supplementation had a similar effect in reducing the prevalence of anaemia and increasing haemoglobin concentrations at the end of the intervention, though in a number of trials, women receiving intermittent supplementation were more likely to have lower ferritin concentrations and fewer side effects at the end of the intervention. There was a dearth of information on morbidity (including malaria outcomes), work performance and economic productivity, depression, and adherence to the intervention; however, to date, there is no evidence that intermittent supplementation has any effect on these outcomes, when compared with placebo, no intervention or with daily supplementation.
The review authors concluded that intermittent iron supplementation in menstruating women may be an effective intervention for reducing anaemia and improving haemoglobin concentrations compared to no treatment, placebo or daily supplementation. Intermittent supplementation may be associated with fewer side effects compared to daily supplementation.
The review authors rated the quality of the evidence as low overall, meaning that the true effect may be substantially different from the estimated effect.
Read the full review here.