Aguayo 2000.

Methods	Randomised double‐blind placebo‐controlled trial. 2‐arm design with individual randomisation.
Participants	73 children (64 children followed up), both sexes (30 females (47%)), aged 6–11.9 years (9 years in average), from outskirts of La Paz, Bolivia (4000 m above sea level). Inclusion criterion: non‐anaemic. Socioeconomic status not reported.
Interventions	Participants were allocated to one of the following groups: Group 1 (n = 37): children received weekly tablets containing iron. The iron dose was calculated to provide children with 3 mg of elemental iron per kg of body weight (approximately 85 mg of iron per week). The supplement consisted of two types of tablets containing either 20 mg or 36 mg of elemental iron (as ferrous sulphate). These tablets were used in combination to adjust the dose to the child’s weight; Group 2 (n = 36): children received a placebo similar in colour and appearance to the iron supplement. Length of the intervention: 18 weeks
Outcomes	Haemoglobin, mean haemoglobin change, anaemia, anthropometric measurements (weight for age Z‐score, height for age Z‐score and mid‐upper arm circumference), and side effects.
Notes	A teacher trained by the principal investigator was responsible for delivering the iron tablets in the classrooms. All children completed at least 17 doses. Pills were administered on Wednesday and students who were not in school on Wednesday were administered the supplements on Thursday. Z‐scores used the National Center for Health Statistics data as a reference. Non‐malaria area.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Children were randomly assigned to the treatment or the control group using a table with randomly assorted digits.
Allocation concealment (selection bias)	Low risk	A teacher trained by the principal investigator was responsible for the delivery of the iron tablets in the classrooms. The teacher was provided with a list of the names of the children and the number and kind of pills (colour coded) each child should take every week. Neither the teacher nor the assistant were aware of the composition of the tablets delivered to the children and tablets were similar in appearance.
Blinding (performance bias and detection bias) All outcomes	Low risk	Tablets were similar in appearance. Participants:Children were not aware of the treatment. Personnel: Neither the teacher nor his assistant were aware of the composition of the tablets delivered to the children Outcome assessors: not described.
Incomplete outcome data (attrition bias) All outcomes	Low risk	A complete set of data was obtained for 33 children in the treatment group (89.2 %) and for 31 children (86.1 %) in the control group
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Low risk	No significant differences at baseline in the variables studied,and females/males ratio. No differences at baseline between those that completed the study and those who dropped out.