Biebinger 2009.

Study characteristics
Methods	Double‐blind, RCT.
Participants	279 women, low body iron stores (serum ferritin less than 25 µg/L), aged 18‐35 year from two colleges in Kuwait: College for women, Kuwait University and the Nursing college public authority for applied education and training.
Interventions	Participants were assigned to one of three groups randomly: group 1 (n = 93) received wheat‐based biscuits produced with wheat flour fortified with 20 mg elemental iron (as reduced iron) NutraFineTM RS) ; group 2 (n = 93) received biscuits fortified with 10 mg of elemental iron (as encapsulated ferrous sulphate) and 150 µg iodine; group 3 (n = 93) received unfortified biscuits. Biscuits were consumed five days per week for 22 weeks.
Outcomes	Serum ferritin, iron stores, and iron deficiency. Adherence: consumption of fortified biscuits was not controlled, and authors report: "it may have been less than expected"
Notes	The FeSO4 treatment group exhibited increased serum ferritin by 88% compared to the control and body iron stores increased from ‐0.96 to 2.24 mg/kg. Reduced iron did not significantly increase serum ferritin or body iron stores. Urinary iodine concentrations increased from 140 to 213 µg/L. prevalence of anaemia at baseline in the target group: < 20% type of iron compound: ferrous sulphate and comparable and low relative bioavailability (reduced iron) estimated wheat flour available per capita: 150‐300 g/day malaria endemicity at the time that the trial was conducted: non/unknown malaria setting duration of intervention: less than six months flour extraction rate: unknown/unreported amount of elemental iron added to flour: more than 60 mg/kg Source of funding: Kuwaiti Flour Mills and Bakeries Company (Kuwait City, Kuwait). , the International Atomic Energy Agency (Vienna, Austria), ETH Zurich (Switzerland), The Medicore Foundation (Liechtenstein), Kuwait Institute for Scientific Research (Kuwait City, Kuwait). Dates of the study: December 2006 to May 2007. Conflict of interest: The authors reported that none of them had conflict of interest.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Authors state, "Subjects meeting the inclusion criteria were randomly assigned to three groups receiving biscuits." Random sequence generation was not specified.
Allocation concealment (selection bias)	Unclear risk	Allocation concealment is not described.
Similarity of baseline outcome measurements (checking for confounding, a potential consequence of selection bias)	Low risk	Authors report " Subjects were invited to join the intervention trial if:(1) they had low Fe stores, defined as a SF concentration < 25 mg/L; (2) were not pregnant or planning pregnancy; (3) had no chronic medical illnesses; (4) did not use vitamin and mineral supplements." Also, baseline overall anaemia level was 15% in the study population. Baseline mean Haemoglobin concentrations (g/dl) were similar across the three arms: Control ‐ 128 g/dl (SD:11), Encapsulated FeSO4 arm ‐ 131 g/dl (SD: 10) and NutraFine arm ‐ 131 g/dl (SD:10).
Similarity of baseline characteristics (checking for confounding, a potential source of selection bias)	Low risk	Authors state that there were no significant differences between control and intervention groups with respect to haemoglobin, anthropometric measures, serum ferritin, or serum transferrin receptor.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote "in the flour storage trial, no significant difference in colour could be detected after 3 months at different temperatures and humidity conditions". "In the triangle testing in both Kuwait and Switzerland, the fortified biscuits were indistinguishable from the non‐fortified biscuits in colour, taste and texture".
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Authors report "Blood samples were transported on ice to Al‐Sabah Hospital in Kuwait City."
Incomplete outcome data (attrition bias) All outcomes	High risk	A total of 65% of the screened subjects completed the Fe fortification efficacy study. Drop outs were due to time constraints, changing residence, Illness, pregnancy.
Selective reporting (reporting bias)	Unclear risk	Changes in Hb, SF, sTfR, body Fe stores, anthropometric reported, however no clinical trial registry available.
Other bias	Low risk	No evidence of other risk of biases.
Recruitment bias	Unclear risk	Not applicable. We evaluated this domain in cluster‐randomised studies only.
Baseline imbalance	Unclear risk	Not applicable. We evaluated this domain in cluster‐randomised studies only.
Loss of clusters	Unclear risk	Not applicable. We evaluated this domain in cluster‐randomised studies only.
Incorrect analysis	Unclear risk	Not applicable. We evaluated this domain in cluster‐randomised studies only.
Comparability with individually Randomised Trials	Unclear risk	Not applicable. We evaluated this domain in cluster‐randomised studies only.