Lin 2008.

Study characteristics
Methods	Randomised, placebo‐controlled trial conducted in Wuhan, an industrial centre in central region of China
Participants	Eligibility: children aged 2–7 years. Children were recruited from kindergarten in the area Excluded: children with fever, diarrhoea or a recent preventive injection; underweight children with BMI age‐ and sex‐specific 5th percentile of the first US National Health and Nutrition Examination Survey data; children whose protein or energy intake met Chinese RDA Sample: 105 children. Mean age 55 months. 61% boys
Interventions	3 intervention groups. 2 consisted of children who were vitamin A deficient and 1 with children who were vitamin A sufficient. Experimental group I (vitamin A deficient):  vitamin A 100,000 IU every month for 3 months Control group I (vitamin A deficient): placebo Control group II (vitamin A sufficient): placebo
Outcomes	All‐cause mortality, mean serum vitamin A levels
Notes	We included data for vitamin A deficient children who were either supplemented with vitamin A or placebo. According to WHO, China does not have a high child mortality rate (i.e. < 40/1000).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "The remaining 70 vitamin A‐deficient children were randomly and equally divided into vitamin A deficient‐supplemented group and vitamin A‐deficient placebo group". Comment: the term 'randomised' is also used to describe a third group that is clearly matched. This may not be a randomised controlled trial.
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient detail provided to make a judgement.
Blinding (performance bias and detection bias) Blinding of participants	Low risk	Quote: "Children of vitamin A‐deficient‐supplemented group were given 100 000 IU (retinol equivalent) vitamin A capsules every 2 weeks for 3 months (Grubesic, 2004). Children of vitamin A‐sufficient placebo group and vitamin A‐deficient placebo group received placebo capsules in the same way".
Blinding (performance bias and detection bias) Blinding of provider	Unclear risk	Comment: although study was double randomised trial, no details of how blinding was achieved was described in the district.
Blinding (performance bias and detection bias) Blinding of outcome assessor	Unclear risk	Comment: insufficient detail provided to make a judgement.
Incomplete outcome data (attrition bias)	Low risk	Comment: no attrition reported.
Selective reporting (reporting bias)	High risk	Comment: main outcome data not reported in a manner that could be analysed.
Other bias	Unclear risk	Comment: as blinding was not described, potential performance bias and other sources of bias could not be assessed.