Do I need to take iron supplements on an empty stomach?

From the Guidelines

Taking iron supplements on an empty stomach is recommended for maximum absorption, but it's not absolutely necessary if you experience side effects. According to the most recent study 1, when patients take oral iron, levels of serum hepcidin increase in response and will remain increased for up to 48 hours, which blocks further iron absorption. Therefore, there is no reason to take iron more than once a day because this will not improve absorption but will increase side effects.

Some key points to consider when taking iron supplements include:

• Taking iron with 80 mg ascorbic acid on an empty stomach improves iron absorption, as it forms a chelate with iron that prevents the formation of insoluble iron compounds and reduces ferric to ferrous iron 1.
• Tea and coffee are powerful inhibitors of iron absorption and should not be consumed within an hour after taking iron 1.
• Avoid taking iron with calcium-rich foods, dairy products, or antacids, as these significantly reduce absorption.
• Split higher doses throughout the day rather than taking all at once.
• If you experience stomach pain, nausea, or constipation, taking iron with a small amount of food can reduce these side effects while still providing benefit.

It's also important to note that the ferrous iron salts (ferrous sulfate, ferrous fumarate, and ferrous gluconate) are a reasonable choice to start with because they are often the least expensive, and there is no substantial evidence that any one product is better than another in effectiveness or tolerance 1.

From the FDA Drug Label

Occasional gastrointestinal discomfort (such as nausea) may be minimized by taking with meals.

It is not necessary to take iron supplements on an empty stomach. In fact, taking them with meals may help minimize gastrointestinal discomfort such as nausea. 2

From the Research

Iron Supplementation

To determine whether iron supplements should be taken on an empty stomach, let's examine the available evidence:

• The study 3 compared the effect of low and high doses of iron supplements on iron deficiency and mild iron-deficiency anemia, but it does not specifically address the timing of iron supplementation in relation to meals.
• Research 4 suggests that oral iron doses should be given on alternate days to maximize fractional iron absorption, but it does not directly discuss taking iron on an empty stomach.
• A study 5 found that iron absorption is higher when iron supplements are taken in the morning, away from meals, and with ascorbic acid, indicating that taking iron on an empty stomach may be beneficial.
• The study 6 notes that gastrointestinal side effects are more common when high levels of supplemental iron are consumed on an empty stomach, implying that taking iron with meals might reduce side effects.
• Another study 7 compared alternate-day and consecutive-day dosing of iron supplements in iron-deficient anemic women and found that alternate-day dosing increases iron absorption, but it does not specifically address the issue of taking iron on an empty stomach.

Key Findings

• Iron absorption may be increased when supplements are taken in the morning, away from meals, and with ascorbic acid 5.
• Gastrointestinal side effects can be reduced by taking iron supplements with meals 6.
• The optimal dosing schedule for iron supplements may involve taking them on alternate days to maximize iron absorption 4, 7.

Considerations for Iron Supplementation

• The timing and dosage of iron supplements can significantly impact their effectiveness and the occurrence of side effects.
• Individual factors, such as the presence of iron deficiency or iron-deficiency anemia, should be considered when determining the best approach to iron supplementation.