Of all the minerals your body needs iron may not be the most important, but it is certainly in the top 5 for long distance runners. Unfortunately, iron can be lost through sweat when working out and through hemolysis or breakdown of the red blood cells in heavy heel strikers (you know who you are)! Supplementing the diet with 20-25 mg/day is one way to ensure you are proactive in restoring the iron lost to your training. As always if you have questions send them to me brian@company5k.com.