In general between 2 and 40 % of iron in food can be absorbed.  The rule of
thumb is that about 10% of iron is usually absorbed.  The amount depends on
the iron needs of the person as the more deficient you are the more you
absorb.  Eggs, tannin in tea and coffee, calcium and phytates decrease iron
absorption.  I have not seen the article refered to in the previous postings.
 Yes, in general iron salts are less well absorbed than other forms of iron.
Supposedly the electrolytic iron used in infant cereals was supposed to be
better absorbed than other forms of iron. Vitamin C enhances iron absorption.
Obviously BM is the best iron source for babies. Hope this helps.
Carol Coughlin, RD
Your Favorite Dietitian