What vitamin should be taken with iron supplements to enhance absorption?

From the Guidelines

Vitamin C should be taken with iron supplements to enhance absorption. When taking an iron supplement, consuming it with a source of vitamin C such as orange juice, a vitamin C supplement (typically 250-500 mg), or vitamin C-rich foods like citrus fruits, strawberries, or bell peppers can significantly increase iron absorption, as noted in the 2024 study by 1. This works because vitamin C converts iron into a more soluble form and counteracts substances that would otherwise inhibit iron absorption. For best results, take your iron supplement with vitamin C at the same time, ideally on an empty stomach. However, avoid taking iron with calcium supplements, dairy products, coffee, tea, or antacids, as these can decrease absorption, as supported by the findings of 1. If you experience stomach upset from iron, you can take it with a small amount of food, though this may slightly reduce absorption. The enhanced absorption from vitamin C can help maximize the benefits of iron supplementation while potentially reducing the dose needed, which may minimize side effects like constipation.

Some key points to consider when taking iron supplements with vitamin C include:

• Taking iron with 80 mg ascorbic acid on an empty stomach improves iron absorption, as shown in a recent iron isotope study mentioned in 1.
• Tea and coffee are powerful inhibitors of iron absorption and should not be consumed within an hour after taking iron, as stated in 1.
• Iron and calcium supplements should be taken 1–2 h apart to avoid affecting absorption of each, as suggested in 1.
• Women of reproductive age and who are menstruating have additional requirements of 50- to 100-mg elemental iron daily, and taking iron supplements alongside citrus fruits/drinks or vitamin C may aid absorption, as noted in 1.

From the Research

Vitamin Enhancement of Iron Absorption

• Vitamin C is known to enhance iron absorption, particularly non-heme iron, as noted in studies 2, 3, 4, 5.
• The mechanism by which vitamin C aids in iron absorption involves the reduction of ferric iron to ferrous iron, which is more soluble and better absorbed by the body.

Studies on Vitamin C and Iron Supplementation

• A study from 1999 2 discussed the role of vitamin C in enhancing iron absorption but also raised questions about potential risks in individuals with high iron stores.
• A 2023 systematic review and meta-analysis 3 found that the addition of vitamin C to iron supplements did not significantly improve hemoglobin or serum ferritin levels in patients with anemia compared to iron supplements alone.
• A randomized clinical trial from 2020 4 concluded 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.
• Another study from 2017 6 focused on the timing and dosing of iron supplements, finding that alternate-day dosing and single morning doses may optimize iron absorption better than daily divided doses.

Effectiveness of Separate Administration of Iron and Vitamin C

• A 2022 study 5 explored the effectiveness of dietary intervention with iron and vitamin C administered separately and found that this approach could be effective in improving iron status in young women, especially those with lower baseline vitamin C intake or better baseline iron status.

Key Findings

• Vitamin C enhances iron absorption, particularly for non-heme iron.
• The necessity of taking vitamin C with iron supplements may depend on individual iron status and baseline vitamin C intake.
• Separate administration of iron and vitamin C can be an effective strategy for improving iron status.