Gilgen 2001.

Study characteristics
Methods	Design: 4‐arm, randomised, double‐blind trial Unit of randomisation: individual level
Participants	Setting/location: North‐East Bangladesh Sample size: 553 non‐pregnant and non‐breastfeeding tea pluckers Age range: 14‐66 years of age (mean age = 39.6 years) Baseline prevalence of anaemia: 85.7% Inclusion criteria: female tea pluckers, non‐pregnant and non‐breastfeeding Exclusion criteria: pregnant and breastfeeding women
Interventions	Participants were allocated to 1 of 4 groups. Group 1 (n = 139): participants received a weekly supplement containing 200 mg of elemental iron (as ferrous fumarate) and 200 μg (0.2 mg) of folic acid. Group 2 (n = 143): participants received anthelmintic treatment on 2 occasions, at the beginning of the trial and 12 weeks later (using a single dose of 40 mg of albendazole). Group 3 (n = 130): participants received a weekly supplement containing 200 mg of elemental iron (as ferrous fumarate) and 200 μg (0.2 mg) of folic acid + single dose of albendazole 400 mg on 2 occasions. Group 4 (n = 141): participants received placebos for both iron supplementation (weekly) and antihelminthic treatment (beginning and 12 weeks later). Length of the intervention: 24 weeks For the purposes of this review, we only compared groups 1 and 4.
Outcomes	Haemoglobin Ferritin Labour productivity Helminth infections Adverse side effects (giddiness, dizziness, nausea, bouts of vomiting, diarrhoea, and stomach pains) Positive side effects (well‐being, feeling stronger and more energetic, feeling relief from stomach pains, anorexia, diarrhoea)
Notes	Comments: We could not extract data on work productivity as they did not include standard deviations. There were no significant differences in the number of days plucked on pruned, unpruned and young tea bushes between the study groups. Of 139 women in the iron‐supplemented group, 87 (62.2%) reported an improvement in well‐being after 24 weeks of iron supplementation. Nearly half (46.6%) felt stronger and more energetic and 15.2% felt relief from stomach pains, anorexia, and diarrhoea. In the placebo group, 51.1% felt better after the study with 38.9% feeling stronger and more energetic, and 6.4% feeling relief from stomach pains, anorexia, and diarrhoea. No screening for malaria parasites was performed as malaria is not known to be endemic in the study region. Study start date: November 1995 Study end date: March 1997 Funding source: UNICEF and The Nestle Foundation. D Gilgen received bursaries from Lucy Cavendish College, Cambridge, the Cambridge Philosophical Society and the University of Cambridge Conflicts of interest: not available
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Comment: participants were randomly assigned to 1 of the study groups. The random number generator in SPSS (Version 7.5) was used to create 4 groups of equal size and the process was repeated until there was no statistically significant difference between the randomised groups in mean age, years of plucking experience, productivity of the previous plucking season, haemoglobin and ferritin values, and prevalence and egg counts of Ascaris, Trichuris and hookworms.
Allocation concealment (selection bias)	Unclear risk	Comment: not mentioned
Blinding (performance bias and detection bias) All outcomes	Low risk	Comment: study described as double‐blind. Participants and personnel were not aware of the treatments; not described for outcome assessors
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: not mentioned
Selective reporting (reporting bias)	Unclear risk	Comment: insufficient information to permit judgement
Other bias	Low risk	Comment: no evidence of other bias