Grosz 2011.

Methods	Type of study: parallel, 4‐arm randomised controlled trial Country of study: Norway Study setting: Oslo Blood Bank Number of participants randomised: 621 (numbers in each treatment arm not reported) Number of participants analysed: not reported Follow‐up time points: 30 days after whole blood donation Source of funding: not reported
Participants	Active blood donors who provided written informed consent Mean age (years): not reported Sex (male/female): not reported
Interventions	Treatment arm 1: standard 20‐day iron supplementation of one tablet (Niferex©) 100 mg Fe2+ per day Treatment arm 2: standard 20‐day iron supplementation combined with a daily high‐dose vitamin C in the form of 1 tablet of 750 mg ascorbic acid (Pharma Nord©) daily for 30 days Treatment arm 3: 30‐day high‐dose vitamin C supplementation only Treatment arm 4: no form of supplementation
Outcomes	Serum ferritin; haemoglobin, serum iron at 30 days
Notes	Insufficient information was included in this conference abstract for inclusion in the review. No further publications of this study have been identified