Swain 2007.

Methods	Design: randomised controlled trial Randomisation: individual Trial: daily oral iron versus electrolytic iron versus reduced iron versus bakery‐grade ferrous sulphate versus placebo. Only daily oral iron and placebo groups extracted Date of study: not stated
Participants	Setting: USA community. No further details given Malaria endemicity: not stated Included: healthy women of child‐bearing age. All women were healthy, menstruating, neither pregnant nor breast‐feeding, and were not using medication (except possibly hormonal contraceptives used for > 6 months). Age range 21 years to 51 years (mean 40 years) Excluded: any other medication Dropouts: 3 of 24; 3 intervention, 0 control Sample size: total: 21; intervention: 9, control: 12
Interventions	Intervention: 5 mg iron as heme iron supplement Control: placebo Duration: 12 weeks
Outcomes	Iron status
Notes	Compliance: 97% of capsules consumed Conflicts of interest: not stated Funded by: Sharing Science and Technology to aid in the improvement of Nutrition, Washington DC
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Sequence generation not described in study
Allocation concealment (selection bias)	Unclear risk	Allocation concealment not described in study
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Placebo administered
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Not reported. Outcomes unlikely to be influenced
Incomplete outcome data (attrition bias) All outcomes	Low risk	4 participants dropped out from study, not clear from which arm
Selective reporting (reporting bias)	Low risk	Not evident
Other bias	Low risk	The study appears to be free of other sources of bias