The Efficacy and Safety of Vitamin C for Iron Supplementation in Adult Patients With Iron Deficiency Anemia: A Randomized Clinical Trial.
Level 2 - randomized trial
Individual randomized controlled equivalence trial
PubMed 33136134 · doi:10.1001/jamanetworkopen.2020.23644
What was done
Adult patients with newly diagnosed iron deficiency anemia (IDA) at a single center in China were randomized 1:1 in an open-label equivalence trial to receive either 100 mg oral iron plus 200 mg vitamin C or 100 mg oral iron alone every 8 hours daily for 3 months (n = 220 per group). The primary outcome was the change in hemoglobin level from baseline to 2 weeks of treatment (equivalence margin of 1.0 g/dL). Secondary outcomes included serum ferritin changes after 8 weeks and adverse events.
What was found
Among 440 randomized patients (mean age 38.3 years; 96.8% female), 432 completed the trial. From baseline to 2 weeks, the mean (SD) change in hemoglobin level was 2.00 (1.08) g/dL in the iron plus vitamin C group and 1.84 (0.97) g/dL in the iron-only group (between-group difference, 0.16 g/dL; 95% CI, -0.03 to 0.35 g/dL), meeting the equivalence criterion. At 8 weeks, the mean (SD) change in serum ferritin was 35.75 (11.52) ng/mL with vitamin C versus 34.48 (9.50) ng/mL without (between-group difference, 1.27 ng/mL; 95% CI, -0.70 to 3.24 ng/mL; P = .21). Adverse event rates did not differ significantly between groups (20.9% vs 20.5%; difference, 0.4%; 95% CI, -6.7% to 8.5%; P = .82).
Why it matters
Routine co-administration of vitamin C with oral iron does not improve hemoglobin recovery or iron store replenishment compared to oral iron alone in adult IDA. This challenges common clinical practice and suggests routine vitamin C co-supplementation is unnecessary.
Limits
The trial was conducted at a single center with an open-label design. The study cohort was overwhelmingly female (96.8%) with a mean age of 38.3 years, limiting generalizability to men, elderly populations, or patients with non-dietary IDA etiologies. Baseline dietary vitamin C intake was not reported in the abstract.
Cited by
- contradicts Co-ingesting vitamin C with iron is necessary or beneficial to assist with iron absorption.