Women with iron deficiency absorb iron supplements more efficiently when taking them every other day, compared to daily, according to new findings published in The Lancet Haematology.
“In contrast with most current recommendations on iron supplementation, our findings indicate that providing oral iron on alternate days in single morning doses increases iron absorption in young women and is an effective regimen to optimize iron absorption,” Dr. Michael B. Zimmermann of ETH Zurich in Switzerland told Reuters Health by email. “This regimen not only improves iron absorption but also, because of its simplicity, might increase compliance.”
At present, guidelines recommend women who require iron supplementation take them in two or three split doses throughout the day, every day, based on the assumption that this will improve iron absorption and be more tolerable for the patient. However, Dr. Zimmermann and his team note in their October 9 report, there is no evidence to support this approach.
The researchers previously found that when two doses of iron were given daily, fractional absorption worsened with the second dose. Patients given two doses a day also had higher levels of hepcidin than those who took a single dose daily.
The new study consisted of two open-label randomized trials. In the first trial, 40 women were randomly assigned to take 60 mg of iron daily for 14 days or 60 mg every other day for 28 days.
In the second trial, 20 women were randomized to receive 120 mg of iron at 8 a.m. once a day or two doses of 60 mg at 8 a.m. and 5 p.m. for three days in a row. Fourteen days later, study participants crossed over to the other treatment.
The researchers used radiolabeled ferrous sulfate to measure iron absorption. In study 1, cumulative fractional iron absorption was 16.3% for the consecutive-day group and 21.8% for the alternate-day group, while cumulative total iron absorption was 131.0 mg versus 175.3 mg, respectively. Hepcidin levels were higher in the consecutive-day group. All of these differences were statistically significant.
In study 2, iron absorption was similar with the once-daily and twice-daily dosing, at 11.8% and 13.1%, respectively. Total iron absorption was 44.3 mg with once-daily dosing and 49.4 mg with twice-daily dosing, not a statistically significant difference. Hepcidin concentrations were significantly higher with twice-daily dosing.
All adverse events reported were grade 1 or 2. In study 1, nausea and abdominal pain were 33% higher with consecutive-day dosing, but the difference did not reach statistical significance.
“Alternate-day oral supplementation with 60 mg iron results in 34% higher iron absorption than with consecutive-day supplementation,” Dr. Zimmermann said. “Splitting a single oral dose of 120 mg iron into two daily doses of 60 mg iron does not improve iron absorption, so the iron can be given in a single dose in the morning.”
He and his colleagues are now planning a similar study in women with iron-deficiency anemia.
“After 350 years of oral iron being used with poor adherence and poor results, we finally have evidence that the way it’s been given may have been suboptimal or even imprudent, and a new paradigm for the use of oral iron may be upon us,” Dr. Michael Auerbach of Georgetown University School of Medicine in Washington, DC, who co-authored an accompanying editorial, told Reuters Health in a telephone interview.
The findings are physiologically plausible, Dr. Auerbach added, given that hepcidin goes up every time a person takes iron, which reduces absorption of subsequent doses.
Further research is needed to determine whether this approach is effective in women with more severe anemia, and whether adherence will decrease with alternate-day dosing, he and co-author Dr. Stanley Schrier of Stanford University School of Medicine conclude.
SOURCES: http://bit.ly/2gAqUha and http://bit.ly/2gL1XzD
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