Omu 2008.

Methods	Randomised controlled open trial Duration of study: unclear
Participants	Country: Kuwait Population: men with asthenozoospermia attending infertility clinic in Kuwait, N = 45 Mean age: 35 ± 1 years Inclusion criteria: asthenozoospermia with normal sperm concentration (20 to 250 million/mL) but with 40% or more immotile sperm Exclusion criteria: asthenozoospermia but sperm concentration of < 20 million/mL
Interventions	Zinc 400 mg (n = 11) versus Zinc 400 mg + Vitamin E 20 mg (n = 12) versus Zinc 400 mg + Vitamin E 20 mg + Vitamin C 10 mg (n = 14) versus No treatment (n = 8) Duration of intervention: 3 months
Outcomes	Sperm parameters
Notes	Attempted to contact author regarding methods of randomisation, it states that quote: "8 men served as non‐ therapy control". No reply as yet (2014).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not mentioned
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	High risk	Control is another antioxidant or no treatment
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Low risk	All outcomes are reported. No dropouts
Selective reporting (reporting bias)	Unclear risk	Outcomes reported. No protocol available.