Taking iron supplements every other day instead of daily is associated with increased iron absorption in women with low iron levels, suggests a small study in The Lancet Haematology.
Roughly 40 women with depleted iron stores (serum ferritin 25 µg/L or less) but not moderate or severe anaemia were assigned to receive iron (60 mg FeSO4) either on consecutive days for 2 weeks or alternate days for 4 weeks. Two weeks after treatment, the alternate-day group had higher fractional iron absorption (22% vs. 16% in the consecutive-day group) and total iron absorption (175 vs. 131 mg).
Next, 20 women received either once-daily dosing (120 mg) or half a dose twice a day, and then crossed over to the other regimen. In this case, absorption levels did not differ between regimens, leading the authors to say that dividing doses "in an attempt to increase iron absorption is unnecessary."
Commentators write that these results "are likely to lead to a more felicitous means of administering this widely used therapy."