The 4 AA formulation increased iron absorption in chow-fed male mice. 2.5 µCi of ⁵⁹Fe in the control (Ctrl) or 4 AA formulation was administered to each mouse by oral, intragastric gavage after a 2-hour fast. Two hours later, mice were sacrificed, and ⁵⁹Fe absorption was quantified (as the percentage of the dose absorbed) (A), and ⁵⁹Fe activity in the blood (B), duodenum (C), and liver (D) were measured. ⁵⁹Fe activity was also assessed in the blood 30 and 60 minutes after gavage (E). Data were analyzed by Student’s t test. n = 14 for control and n = 15 for 4 AAs; *P < .05, **P < .01. One statistical outlier was removed from the Ctrl data set in (C) (marked in red).