From the Guidelines
It is generally okay to take iron tablets with food, but this may decrease absorption, and patients should be aware of this potential trade-off between tolerability and efficacy. When considering iron supplementation, it's essential to weigh the benefits of reduced gastrointestinal side effects against the potential decrease in absorption 1. Taking iron supplements with food can improve tolerability, but certain foods like dairy products, coffee, tea, whole grains, or calcium supplements can further decrease iron absorption.
To optimize absorption, patients can take iron supplements with vitamin C-rich foods like orange juice or with a vitamin C supplement 1. The standard dosage for iron deficiency in adults is typically 150-200 mg of elemental iron daily, although some studies suggest that lower dosing or every-other-day dosing may improve tolerability and absorption 1. If possible, patients should try taking iron between meals with a small amount of vitamin C for maximum absorption, but if this causes stomach discomfort, taking it with food is preferable to skipping doses.
Key considerations for iron supplementation include:
- Starting with an initial trial of oral iron supplementation, as it is generally effective, available, inexpensive, and safe 1
- Recognizing that gastrointestinal intolerance to oral iron supplements is common, and patients with malabsorption syndromes may have limited response 1
- Monitoring for a response to oral iron supplementation, typically evident within 1 month of treatment, and assessing for nonadherence, malabsorption, or ongoing blood loss if no response is seen 1.
From the FDA Drug Label
Occasional gastrointestinal discomfort (such as nausea) may be minimized by taking with meals. It is ok to take iron tablets with food, as this may help minimize gastrointestinal discomfort such as nausea 2.
- Taking iron tablets with meals is recommended to reduce the risk of gastrointestinal side effects.
From the Research
Iron Tablet Consumption with Food
- It is generally recommended to take iron supplements in the morning, away from meals, to maximize absorption 3.
- However, the effect of taking iron tablets with food is not entirely clear, and more research is needed to fully understand the relationship between food consumption and iron absorption.
- A study found that consuming iron supplements with coffee or breakfast decreased iron absorption by 54% and 66%, respectively, despite the presence of ascorbic acid (AA) in the breakfast 3.
- Another study suggested that taking iron supplements with orange juice alone resulted in a ~4-fold increase in iron absorption compared to consuming it with coffee or breakfast 3.
Types of Iron Supplements
- Ferrous bisglycinate is a novel amino acid iron chelate that is thought to be more bioavailable and associated with fewer gastrointestinal adverse events compared to iron salts 4.
- Ferrous gluconate is another form of iron supplement that has been shown to be effective in increasing hemoglobin and ferritin concentrations in adults and children 5, 6.
- The choice of iron supplement may depend on individual factors, such as the presence of gastrointestinal side effects or the need for a more bioavailable form of iron.
Bioavailability and Absorption
- The bioavailability of iron supplements can be affected by various factors, including the type of iron salt, the presence of ascorbic acid, and the timing of consumption 3, 4.
- Ferrous gluconate has been shown to have a higher iron absorption rate compared to ferrous fumarate in a rice flour system, particularly in a low phytic acid environment 6.
- The absorption of iron supplements can also be influenced by the presence of other nutrients, such as vitamin C, which can enhance iron absorption 3.