My doctor told me to take 3 iron pills per day. Then another doctor told me to look at Iron Dosing for Optimal Absorption by David Green, MD, PhD reviewing Moretti D et al. Blood 2015 Oct 22. Their study concluded that more iron is absorbed if a single pills is taken every other day instead of 1 or more pills each day. This is certainly counter-intuitive, but a clinical trial proved it to be true for iron-depleted young women, at least.