Timing of iron supplementation
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Timing and Frequency of Iron Supplementation: Key Findings
Daily vs. Alternate-Day Iron Supplementation
Recent research shows that giving iron supplements on alternate days, rather than consecutive days, can improve iron absorption in women with iron deficiency and iron-deficiency anemia. This is because daily or split dosing increases serum hepcidin, a hormone that reduces iron absorption, while alternate-day dosing allows hepcidin levels to decrease, leading to better absorption of iron from each dose 457. Studies found that fractional iron absorption was 40-50% higher with alternate-day dosing compared to consecutive-day dosing, and total iron absorption was also greater when a higher dose was given every other day . Additionally, alternate-day dosing resulted in fewer gastrointestinal side effects compared to daily dosing .
Once-Daily vs. Twice-Daily Dosing
Research comparing once-daily and twice-daily iron supplementation in pregnant women found no significant difference in the change in hemoglobin or hematocrit levels between the two groups. However, twice-daily dosing did not increase gastrointestinal side effects compared to once-daily dosing . In non-pregnant women, studies suggest that single morning doses are preferable to split doses throughout the day, as split dosing can further increase hepcidin and reduce iron absorption 45.
Duration of Iron Supplementation
For children and adolescents with iron deficiency anemia, both short-term (less than 3 months) and long-term (more than 6 months) iron supplementation were effective in improving hemoglobin levels, with the highest effect seen in treatments lasting less than 3 months . In children, shorter (1–3 months) and longer (7+ months) durations of supplementation generally showed similar benefits, except that ferritin levels increased more with longer supplementation .
Morning vs. Evening Supplementation
A study in dancers found that taking iron supplements in the morning or evening was equally effective in increasing serum ferritin levels over an 8-week period, suggesting that the time of day may not significantly impact the effectiveness of supplementation in this context . However, other research indicates that iron absorption is higher in the morning due to lower hepcidin levels, and that taking iron with ascorbic acid (vitamin C) and away from meals or coffee further increases absorption 59.
Weekly vs. Daily Supplementation
Weekly and intermittent iron supplementation (1–2 times per week) were found to be similarly effective as daily regimens in reducing anemia and iron deficiency in children and adolescents, although daily supplementation led to slightly higher increases in ferritin and hemoglobin levels . Another study found no significant difference in iron absorption between daily and weekly supplementation in women, suggesting that less frequent dosing may be a viable option for some individuals .
Conclusion
The timing and frequency of iron supplementation can significantly affect iron absorption and treatment outcomes. Alternate-day dosing, single morning doses, and taking iron with vitamin C and away from meals or coffee are strategies that can optimize absorption and minimize side effects in many populations. Both short and long durations of supplementation are effective, and weekly regimens may be suitable for some groups. Tailoring iron supplementation schedules to individual needs and baseline iron status is important for maximizing benefits and minimizing adverse effects 1345789.
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