Does vitamin C improve response to oral iron therapy?

A gastric acid milieu facilitates intestinal iron absorption. For patients with iron deficiency anaemia who are treated with oral iron, some authorities recommend that ascorbic acid (vitamin C) be taken along with iron. Although evidence suggests that vitamin C enhances iron absorption, the clinical value of this practice is unclear. In a randomised trial from China, researchers assigned 440 patients with documented iron deficiency anaemia to receive either ferrous succinate (100 mg) plus vitamin C (200 mg) three times daily or ferrous succinate alone. Nearly all participants were young women with menorrhaegia as the cause of iron deficiency.

At baseline, mean haemoglobin was 8.8 g/dL; during 8 weeks of follow-up, haemoglobin increased by 4 mg/dL in both groups. Additionally, improvements in serum ferritin and iron were not significantly different in the two groups.

Vitamin C did not facilitate response to oral iron supplementation in this trial. However, an important limitation is the homogeneous study population — young women with menorrhaegia. Whether these findings translate to other patient groups, some of whom might have hypochlorhydria, is unclear. For example, iron-deficient patients who take proton-pump inhibitors chronically — and who require ongoing acid-suppressive therapy — might benefit from combining vitamin C and oral iron.