Radhakrishna 2013.

Methods	RCT Sample size: 324 infants Inclusion criteria: term healthy infants who would stay in the study area until the child attained 2 years of age Exclusion criteria: preterm deliveries (gestational age < 37 weeks), LBW (< 2500 g) and infants with congenital abnormalities (neural tube defects, congenital heart disease, cleft palate, and cleft lip) or birth asphyxia
Participants	Infants Age: birth Country: India Setting: low‐income urban communities (population of around 25,000 located in the Secunderabad city of the South India)
Interventions	Type: zinc supplementation in infants aged 4–18 months. Mothers were counselled on strategies to overcome problems with supplement adherence. Clinic conducted at community centre for study children and treat illnesses (respiratory tract infections, dysentery). Every month, the project staff, responsible for distributing the supplements in the field, collected empty bottles, and provided fresh supplements as per participant identification number and codes. Urban specificity: none Level of factors tackled: individual, service delivery, community Delivery: community groups, service delivery stakeholders, city, and regional governance Duration (years): 1.2 Comparison: IG: zinc 5 mg + riboflavin 0.5 mg/day CG: riboflavin 0.5 mg/day Measurement: weight and length measured at enrolment and again after 3 and 6 months PROGRESS at baseline: maternal age, father's age, number of family members, number of antenatal visits
Outcomes	Length, HFA, weight at 18 months, WFH, skinfold thickness (triceps, sub scapular)
Notes	Funding: no information provided Impact of the intervention: IG: HFA at 18 months 61.6%, 21 months 39%, 24 months 29.5%; WFH at 18 months 6.5%, 21 months 11.8%, 24 months 14.3% CG: HFA at 18 months 61.9%, 21 months 25.1%, 24 months 25.2%; WFH at 18 months 10.1%, 21 months 19.1%, 24 months 24.6%
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random sequence generation was computer‐generated and administered by a separate scientist to the study team.
Allocation concealment (selection bias)	Low risk	Intervention was concealed Quote: "The zinc and placebo were prepared and supplied by Biological Evans Limited, in a syrup base, which were of similar colour, consistency and flavour; in two sets of identical looking bottles, labelled 1 and 2."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	There was a robust system for minimising performance bias.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	There was a robust system for minimising detection bias (see text under 'Blinding of participants and personnel (performance bias)' for evidence).
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	There was a reasonably low rate of attrition (163 infants began in the IG and 9 were lost to follow‐up; 161 began in the CG and 13 were lost to follow‐up) and so it is unlikely to have had great effect on the results. Nevertheless, there was no intention‐to‐treat analysis so it was not possible to fully assess the effect of the attrition.
Selective reporting (reporting bias)	Low risk	The study protocol identified the primary outcomes to be reported upon; these were reported in the paper.
Other bias	Unclear risk	None identified. Unclear if the participants benefited from other ongoing interventions during the study period.
Similarity of outcome measures at baseline	Low risk	No statistically significant difference in the outcome measures at baseline.
Similarity of baseline characteristics	Low risk	No statistically significant difference in the characteristics between the CG and IG.
Protection against contamination	Low risk	Community‐based supplementation study where mothers were given bottles to administer at home. Risk of mother sharing bottles was low.