Every other day refilled iron stores as well as daily, in one trial
In 150 young women who were not anaemic, ferritin finished at 44.8 against 43.8 micrograms per litre. Stomach side effects were 1.56 times as common on the daily schedule.
What the study found
Alternate-day iron repletes just as well, with fewer side effects
At equal total doses, ferritin finished at 44.8 micrograms per litre on the alternate-day schedule and 43.8 on the daily one, p=0.98. What the alternate-day schedule bought was tolerability: on days iron was taken, stomach side effects were 1.56 times as common under daily dosing.
The caveat · Only young Swiss women, none anaemic
The trial's one favourable repletion number is a secondary outcome at p=0.049 resting on roughly 2 women against 8, which is too few to build on. It ran at a single centre in 150 young Swiss women, none of them anaemic, so it does not establish the same schedule in men, in older adults, or in anyone with iron-deficiency anaemia.