Alternate day versus consecutive day oral iron supplementation in iron-depleted women: a randomized double-blind placebo-controlled study

• Published in: EClinicalMedicine 2023-11, Vol.65, p.102286-102286, Article 102286
• Main Authors: von Siebenthal, Hanna K., Gessler, Sara, Vallelian, Florence, Steinwendner, Joachim, Kuenzi, Urs-Martin, Moretti, Diego, Zimmermann, Michael B., Stoffel, Nicole U.
• Format: Article
• Language: English
• Subjects: Alternate day; Daily; Deficiency; Gastrointestinal side effects; Hepcidin; Iron; Supplementation
• ISSN: 2589-5370; 2589-5370
• DOI: 10.1016/j.eclinm.2023.102286

Guidelines to treat iron deficiency recommend daily provision of oral iron, but this may decrease fractional iron absorption and increase side effects. Our objective was to compare consecutive-day versus alternate-day iron supplementation. In a double-masked, randomized, placebo-controlled trial, young Swiss women (n = 150; serum ferritin ≤30 μg/L) were assigned to: daily 100 mg iron for 90 d, followed by daily placebo for another 90 d (consecutive-day group) or the same daily dose of iron and placebo on alternate days for 180 d (alternate-day group). The study period was 24/11/2021–10/8/2022. Co-primary outcomes, at equal total iron doses, were serum ferritin and gastrointestinal side effects; secondary outcomes were iron deficiency and serum hepcidin. Compliance and side effects were recorded daily using a mobile application. Data were analysed using mixed models and longitudinal prevalence ratios (LPR). The trial was registered at ClinicalTrials.gov (NCT05105438). 75 women were assigned to each group and included in the intention-to-treat analysis. Capsule adherence and side effect reporting was >97% in both groups. At equal total iron doses, comparing consecutive-day and alternate-day groups, median serum ferritin was 43.8 μg/L (31.7–58.2) versus 44.8 μg/L (33.8–53.6) (P = 0.98), the LPR for gastrointestinal side effects on days of iron intake was 1.56 (95% CI: 1.38, 1.77; P