Best time of day to take iron supplements

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Optimal Timing for Iron Supplementation: Morning vs. Evening

Morning Iron Supplementation: Enhanced Absorption

Research indicates that taking iron supplements in the morning can significantly enhance iron absorption. A study involving iron-depleted women found that consuming iron supplements in the morning, away from meals and coffee, and with an ascorbic acid (AA)-rich beverage, such as orange juice, maximized iron absorption. Specifically, 80 mg of AA increased fractional iron absorption (FIA) by 30%, while coffee reduced FIA by 54% . Additionally, serum hepcidin levels, which inhibit iron absorption, were lower in the morning compared to the afternoon, further supporting morning supplementation .

Alternate-Day Dosing: Maximizing Iron Absorption

Recent studies suggest that alternate-day dosing of iron supplements may be more effective than daily dosing. This regimen helps to avoid the acute increase in serum hepcidin that follows iron intake, which can persist for 24 hours and reduce iron absorption from subsequent doses. In iron-deficient women, alternate-day dosing resulted in higher cumulative fractional iron absorption compared to consecutive-day dosing 235. This approach also minimizes gastrointestinal side effects, improving overall compliance .

Evening Iron Supplementation: Comparable Efficacy

While morning supplementation is generally recommended, some studies have shown that evening supplementation can be equally effective. An 8-week study on ballet and contemporary dancers found no significant difference in serum ferritin (sFer) levels between those who took iron supplements in the morning and those who took them in the evening. Both groups experienced significant increases in sFer levels, indicating that the timing of supplementation (morning vs. evening) did not affect the efficacy of iron absorption .

Twice-Daily Dosing: Less Effective

Twice-daily dosing of iron supplements has been shown to be less effective due to the increased serum hepcidin levels it induces. A study comparing once-daily and twice-daily dosing found no significant difference in total iron absorption between the two regimens, but twice-daily dosing resulted in higher serum hepcidin concentrations, which can inhibit iron absorption 37. Therefore, single morning doses are preferable to split doses throughout the day.

Conclusion

To optimize iron absorption, it is recommended to take iron supplements in the morning, away from meals and coffee, and with an ascorbic acid-rich beverage. Alternate-day dosing is also beneficial as it maximizes iron absorption and minimizes side effects. While evening supplementation can be effective, morning doses are generally preferred due to lower hepcidin levels. Avoiding twice-daily dosing can further enhance iron absorption and improve overall treatment efficacy.

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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·

12citations

·Hanna K. von Siebenthal 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·

84citations

·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·

299citations

·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.

Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women

Alternate-day dosing of oral iron supplements increases iron absorption in iron-deficient anemic women, potentially improving their iron status.

Non-RCTHighly Cited

2019·

131citations

·Nicole U. Stoffel et al.

Iron absorption from oral iron supplements given on consecutive versus alternate days in iron-depleted women

Alternate day dosing of oral iron supplements for 28 days leads to higher fractional absorption than daily dosing for 14 days, partly due to differences in hepcidin production.

RCT

2018·

3citations

·T. Goodsall et al.

Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women.

Lower dosages (40-80 mg) and alternate-day supplementation maximize iron absorption in iron-depleted young women, while twice-daily dosing reduces fractional absorption.

Non-RCTHighly Cited

2015·

425citations

·Diego Moretti 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.

Intermittent iron supplementation for reducing anaemia and its associated impairments in adolescent and adult menstruating women.

Intermittent iron supplementation effectively reduces anaemia risk and improves haemoglobin concentration in menstruating women compared to no intervention or a placebo.

Meta-AnalysisVery Rigorous Journal

2019·

64citations

·A. C. Fernández-Gaxiola 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·

19citations

·Mary A. Uyoga et al.

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