From the Guidelines
Ascorbic acid should be used with iron supplements to improve absorption, as recommended by the most recent clinical practice update on management of iron deficiency anemia. When taken together with iron, ascorbic acid converts iron to its ferrous form, which is more readily absorbed in the intestines 1. For optimal results, taking iron with 80 mg of ascorbic acid on an empty stomach improves iron absorption, as shown in a recent iron isotope study 1. This combination is particularly beneficial for individuals with iron deficiency anemia or those at risk of poor iron absorption.
Key Considerations
- The timing of taking iron with vitamin C matters, with optimal absorption achieved when taken on an empty stomach, typically 1 hour before or 2 hours after meals.
- If stomach upset occurs, iron can be taken with food, but it is essential to avoid calcium-rich foods, coffee, tea, and dairy products, as these can inhibit iron absorption 1.
- Ascorbic acid creates an acidic environment in the stomach and intestines, keeping iron in its more soluble and absorbable ferrous state, potentially increasing absorption by up to 3-6 times compared to taking iron alone.
Important Interactions
- Tea and coffee are powerful inhibitors of iron absorption and should not be consumed within an hour after taking iron 1.
- Certain dietary manipulations, such as taking iron with vitamin C, may improve iron absorption, but further study is needed to clarify the effectiveness of this practice 1.
From the Research
Reasons for Using Ascorbic Acid with Iron
- Ascorbic acid enhances the absorption of nonheme iron, which is the primary form of iron in most diets 2.
- It reverses the effect of dietary inhibitors and is one of the most powerful known promoters of nonheme iron absorption 2.
- Ascorbic acid facilitates iron absorption by forming a chelate with ferric iron in food at the acid pH of the stomach, keeping the iron soluble at the alkaline pH of the duodenum 2.
Mechanism of Action
- Ascorbic acid acts as an electron donor for duodenal ferri-reductase activity, supporting an intracellular role in intestinal iron absorption 3.
- It can react as both a pro-oxidant and an antioxidant, with the balance depending on its concentration 3.
Effectiveness of Ascorbic Acid with Iron
- The consumption of ascorbic acid with a meal containing nonheme iron can improve iron absorption, especially in individuals with diets low in heme iron 2.
- However, the effectiveness of ascorbic acid in promoting iron absorption from less soluble compounds, such as ferrous fumarate and elemental iron, requires further investigation 4.
- Studies have shown that ascorbic acid can enhance iron absorption, but the long-term effect on iron status may be less than predicted from single meal studies 4.