Best time to take iron

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Optimal Timing for Iron Supplementation: Morning vs. Afternoon

Morning Iron Supplementation: Enhanced Absorption

Research consistently indicates that taking iron supplements in the morning can significantly enhance iron absorption. A study involving iron-depleted women demonstrated that consuming iron in the morning, especially with ascorbic acid (vitamin C), increased fractional iron absorption (FIA) by 30% compared to taking it with water alone . This effect was not further enhanced by higher doses of ascorbic acid, but it was notably reduced when iron was taken with coffee or breakfast . Additionally, serum hepcidin levels, which inhibit iron absorption, were found to be lower in the morning, further supporting the efficacy of morning supplementation .

Impact of Exercise on Iron Absorption

For athletes, the timing of iron supplementation relative to exercise also plays a crucial role. A study on endurance-trained runners found that iron absorption was significantly higher when supplements were taken in the morning post-exercise compared to the afternoon . This suggests that the post-exercise window in the morning may provide a transient mechanism that promotes iron absorption, counteracting the inhibitory effects of elevated hepcidin levels .

Alternate-Day Dosing: A Superior Strategy

Recent studies have also explored the frequency of iron supplementation. It has been shown that taking iron supplements on alternate days rather than consecutive days can optimize iron absorption. This regimen prevents the persistent elevation of hepcidin levels, which can inhibit iron absorption 45. For instance, a study comparing consecutive and alternate-day dosing found that alternate-day dosing resulted in higher cumulative fractional iron absorption and lower serum hepcidin levels .

Evening Supplementation: Comparable Efficacy

Interestingly, some research suggests that evening supplementation may be just as effective as morning supplementation. A study on ballet and contemporary dancers found no significant difference in the increase of serum ferritin levels between those who took iron in the morning and those who took it in the evening over an eight-week period . This indicates that while morning supplementation may have certain advantages, evening supplementation can still be effective, particularly for individuals who may experience gastrointestinal discomfort from morning doses.

Conclusion

In summary, the optimal time to take iron supplements appears to be in the morning, especially when combined with ascorbic acid and away from meals or coffee, to maximize absorption. For athletes, taking iron post-morning exercise can further enhance absorption. Additionally, adopting an alternate-day dosing schedule can improve iron absorption and reduce side effects. However, evening supplementation remains a viable option for those who may prefer it or experience discomfort with morning doses.

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Most relevant research papers on this topic

Effect of dietary factors and time of day on iron absorption from oral iron supplements in iron deficient women

Consuming iron supplements in the morning, away from meals or coffee, and with an ascorbic acid-rich food or beverage increases iron absorption by 4-fold in iron deficient women.

Non-RCT

2023·

13citations

·Hanna K. von Siebenthal et al.

ON THE ANALOGY BETWEEN SPONTANEOUS RECOVERIES FROM CANCER AND THE SPECIFIC IMMUNITY INDUCED BY X RAY IRRADIATIONS OF THE LYMPHATIC GLANDS INVOLVED *

The study suggests that spontaneous cancer recovery may be linked to specific immune responses in lymphatic glands involved.

1908·

12citations

·H. Mcculloch

The Impact of Morning versus Afternoon Exercise on Iron Absorption in Athletes.

Morning exercise improves iron absorption in athletes, while afternoon exercise increases inflammation and hepcidin levels, but iron absorption is best absorbed in the morning.

Very Rigorous Journal

2019·

26citations

·R. McCormick et al.

Oral iron supplementation in iron-deficient women: How much and how often?

Morning doses of 60-120 mg iron with ascorbic acid on alternate days may be an optimal oral dosing regimen for women with iron-deficiency and mild iron deficiency anemia.

Literature ReviewHighly Cited

2020·

90citations

·Nicole U. Stoffel et al.

Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials.

Oral iron supplements given alternate days and as single morning doses have better iron absorption than those given daily or split doses in iron-depleted women.

RCTHighly Cited

2017·

308citations

·Nicole U. Stoffel et al.

Timing is everything, but does it really matter? Impact of 8-weeks morning versus evening iron supplementation in ballet and contemporary dancers

Oral iron supplementation in either the morning or evening is equally effective in increasing serum ferritin levels in elite ballet and contemporary dancers with sub-optimal iron status.

RCT

2023·

4citations

·Caitlin Attwell et al.

When taking iron, a glass of orange juice a day keeps anemia away

A glass of orange juice a day is optimal for maximizing absorption of oral iron, reducing the risk of gastrointestinal adverse events and promoting optimal treatment outcomes.

2023·

2citations

·J. Powers et al.

Efficacy of weekly compared with daily iron supplementation.

Weekly iron supplementation does not significantly improve absorptive efficiency compared to daily administration.

RCTHighly Cited

1995·

132citations

·J. D. Cook et al.

The effect of iron dosing schedules on plasma hepcidin and iron absorption in Kenyan infants.

In Kenyan infants, morning and afternoon doses of 12 mg oral iron are equally absorbed, dosing on consecutive days increases plasma hepcidin and slightly decreases iron absorption, while alternate day or every third day dosing does not affect hepcidin levels or absorption.

Non-RCTVery Rigorous Journal

2020·

20citations

·Mary A. Uyoga et al.

Diurnal variation of serum iron, iron-binding capacity, transferrin saturation, and ferritin levels.

Restricting iron specimen collections to a specific time of day does not improve the reliability of the test result.

Observational StudyHighly Cited

2002·

166citations

·J. Dale et al.

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