Mostafa 1989.

Methods	RCT of parallel group design
Participants	67 volunteers, recruited at the University of Mississippi Campus, Mississippi, USA. No further inclusion/exclusion criteria for participants was specified.
Interventions	Intervention (n = 37): One 500 mg vitamin C tablet per day for 6 months. Particpants were instructed to avoid taking vitamin C from other sources and it was emphasised that they will not alter their diet habits or their lifestyle. Control (n = 30): Placebo, for 6 months (no further details provided).
Outcomes	Systolic blood pressure, diastolic blood pressure, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides.
Notes	Age, gender and ethnicity were not stated in the paper. Outcome data for the control group were not provided in the paper and so data are insufficient for use in meta‐analyses. Before and after results where provided by the authors are described in the results text. Review author NF could not find any contact details for the authors of this paper. Funding source: not stated.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated.
Allocation concealment (selection bias)	Unclear risk	Not stated.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Double blind techniques were used to exclude the possibility of bias. Neither the subjects, nor staff knew which subjects had taken the vitamin C or placebo regimens".
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No details provided.
Selective reporting (reporting bias)	High risk	Outcome data were not reported for the control group.
Other bias	Unclear risk	Insufficient information to judge. Did not state funding.