Is a daily dose of 250mg of vitamin C with iron supplementation excessive?

From the Guidelines

A daily dose of 250mg of vitamin C with iron supplementation is excessive for patients with haemochromatosis, but may be acceptable for most adults without iron overload disorder. The recommended dietary allowance (RDA) for vitamin C is 75-90mg for adults, but the upper tolerable limit is 2,000mg per day, so 250mg falls well within safe limits for most adults 1. However, for patients with haemochromatosis, it is prudent to counsel them to avoid supplemental vitamin C, especially when they are iron overloaded and during the induction phase, and to discuss any eventual supplementation with a physician, limiting the dosage to 500 mg daily 1. Some key points to consider:

• Vitamin C significantly enhances iron absorption, particularly non-heme iron found in plant foods, which can be beneficial for individuals with iron deficiency anemia or those at risk of deficiency, such as menstruating women, pregnant women, or vegetarians 1.
• Taking iron supplements alongside citrus fruits/drinks or vitamin C may aid absorption, but iron and calcium supplements should be taken 1–2 h apart to avoid affecting absorption of each 1.
• Patients with haemochromatosis should have a healthy diet, avoid iron and vitamin C supplementation, and limit meat consumption, especially red meat, to reduce iron intake 1.
• The optimal drug, dosage, and timing of oral iron replacement therapy (IRT) for adults with iron deficiency anemia are not clearly defined, but a once-daily dose of 50–100 mg of elemental iron may be the best compromise option for initial treatment 1.

From the Research

Daily Vitamin C and Iron Supplementation

• The daily dose of 250mg of vitamin C with iron supplementation is not considered excessive based on available research 2, 3, 4.
• A study published in The American Journal of Clinical Nutrition established a tolerable upper intake level for vitamin C at 2000mg per day for adults, indicating that 250mg is well within the safe range 2.
• Another study found that high-dose intakes of vitamin C do not cause iron imbalance in healthy individuals and probably not in those who are heterozygous for hemochromatosis 3.
• However, individuals with a history of kidney stone formation and those who experience iron overload should exercise caution when using supplemental vitamin C 4.

Safety and Efficacy of Vitamin C with Iron

• A randomized clinical trial published in JAMA Network Open 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 5.
• The study suggests that on-demand vitamin C supplements are not essential to take along with oral iron supplements for patients with iron deficiency anemia 5.
• Another study argued that the optimum intake of vitamin C in humans is 200mg per day to maximize the vitamin's potential health benefits with the least risk of inadequacy or adverse health effects 6.

Potential Risks and Benefits

• High intakes of vitamin C have not been found to increase oxidative damage in humans, and most studies have shown that diets rich in vitamin C are inversely related to the incidence of coronary heart disease and cancer 3.
• Vitamin C acts as a biological antioxidant that can lower elevated levels of oxidative stress, which may contribute to chronic disease prevention 6.
• However, individuals with certain medical conditions, such as hemochromatosis, should avoid high intakes of vitamin C and iron to prevent potential adverse effects 3, 4.