Garland 2006.

Study characteristics
Methods	RCT, quadruple‐blind in USA
Participants	178 (male/female: 89/89) participants: 42 (male/female: 21/21) in group A, 63 (male/female: 31/32) in group B and 73 (male/female: 37/36) in group C, 89 men
Interventions	Group A: green tea beverage and placebo capsules Group B: placebo beverage and Polyphenon E capsules (Mitsui‐Norin Co, Ltd, Shizuoka, Japan), corresponding to 800 mg/d of ECGC Group C: placebo beverage and placebo capsules Duration: 6 months
Outcomes	Primary outcome Change in levels of biomarkers of oxidative stress Secondary outcome Safety data
Green tea in exposure categories	N/A
Notes	No results on lung cancer prevention published or reported on ClinicalTrials.gov (NCT00363805)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "We are conducting a 6‐month randomized, controlled, double‐blind trial..." Comment: probably done
Allocation concealment (selection bias)	Unclear risk	No statement
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Review authors do not believe this would introduce bias since all biological analyses were performed
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Review authors do not believe this would introduce bias since all biological analyses were performed
Incomplete outcome data (attrition bias) All outcomes	High risk	Data on lung cancer NR, only on biomarkers
Selective reporting (reporting bias)	Low risk	All outcomes reported on ClinicalTrials.gov (NCT00363805)
Other bias	Unclear risk	The number of withdrawals is low, however since no full publication is available, only an abstract and report on ClinicalTrials.gov, it is difficult to judge if other biases are present.