From the Guidelines
Taking 80 mg of vitamin C (ascorbic acid) with iron supplements is recommended to enhance iron absorption, as it forms a chelate with iron and reduces ferric to ferrous iron, thereby improving absorption. This recommendation is based on a recent iron isotope study 1. When taking vitamin C with iron supplements, it is best to take them on an empty stomach to maximize absorption. Vitamin C can increase iron absorption, but the evidence supporting its administration to improve iron absorption is mixed, and further study is needed to clarify the effectiveness of this practice 1.
Key Considerations
- Take iron supplements no more than once a day, as increased frequency does not improve absorption but may increase side effects 1.
- Avoid consuming tea and coffee within an hour after taking iron supplements, as they can inhibit iron absorption 1.
- While some studies suggest that taking iron every other day may improve tolerance, this approach needs to be better studied before being implemented 1.
- The combination of vitamin C and iron supplements is particularly beneficial for those taking non-heme iron, as it is less readily absorbed than heme iron from animal sources.
Comparison with Other Guidelines
A previous guideline 1 suggested that ascorbic acid (250-500 mg twice daily with the iron preparation) may enhance iron absorption, but there are no data for its effectiveness in the treatment of iron deficiency anemia. However, the more recent study 1 provides stronger evidence for the use of vitamin C to enhance iron absorption, with a recommended dose of 80 mg.
Clinical Implications
In clinical practice, taking 80 mg of vitamin C with iron supplements is a simple and effective way to enhance iron absorption, particularly for patients with iron deficiency or anemia. This approach can help improve treatment outcomes and reduce the risk of side effects associated with iron supplements.
From the FDA Drug Label
DRUG INTERACTIONS 7.1 Antibiotics Ascorbic acid may decrease activities of erythromycin, kanamycin, streptomycin, doxycycline, and lincomycin. Bleomycin is inactivated in vitro by ascorbic acid. If the antibiotic efficacy is suspected to be decreased by concomitant administration of ASCOR, discontinue ASCOR administration.
The FDA drug label does not answer the question about the vitamin C dose supplement with Iron supplement.
From the Research
Vitamin C and Iron Supplementation
- The efficacy of vitamin C as a co-intervention with iron for anemia has been studied in several clinical trials 2, 3.
- A systematic review and meta-analysis of experimental studies found that the pooled estimate for standardized mean difference of hemoglobin and serum ferritin for intervention-type ferrous ascorbate and oral iron and vitamin C were not statistically significant 2.
- A randomized clinical trial found that oral iron supplements alone were equivalent to oral iron supplements plus vitamin C in improving hemoglobin recovery and iron absorption in patients with iron deficiency anemia 3.
- Another study found that ascorbic acid enhances iron absorption and is actively involved in the control of iron metabolism, with a dual role as pro-oxidant and antioxidant depending on concentration 4.
Mechanism of Action
- Ascorbic acid reduces ferric to ferrous iron, making it more soluble and bioavailable for absorption 5.
- The iron absorption-enhancing effect of ascorbic acid is more potent than that of other organic acids due to its ability to reduce ferric to ferrous iron 5.
- Sucrosomial iron, an oral formulation consisting of ferric pyrophosphate conveyed by a phospholipid and sucrester matrix, has been found to have higher iron intestinal absorption and excellent gastrointestinal tolerance compared to oral iron salts 6.
Clinical Implications
- The use of vitamin C as a co-intervention with iron for anemia may not be essential for patients with iron deficiency anemia, as oral iron supplements alone have been found to be equivalent to oral iron supplements plus vitamin C in improving hemoglobin recovery and iron absorption 3.
- Sucrosomial iron may be a valid first option for the treatment of iron deficiency and iron deficiency anemia, especially for subjects who are intolerant or refractory to conventional iron salts 6.