Iron stores and iron absorption: effects of repeated blood donations.

We assessed changes in iron stores and iron absorption after repeat blood donations using a combination of biochemical measures of iron status: ferritin, hemoglobin, and transferrin saturation. Thirty-six volunteers with a mean (+/- SD) age of 67.7 +/- 3.7 y donated an average of 15 units of blood over 3.5 y. Initial iron stores were 12.45 +/- 3.09 mg/kg for men and 12.53 +/- 3.24 mg/kg for women. Of the 20 men and 16 women who completed the study, 6 men and 10 women were taking a self-selected supplement providing approximately 20 mg Fe/d. Dietary iron intake was determined to be approximately 20 mg/d for men and approximately 18 mg/d for women. Decreases in iron stores in supplemented men were not significantly different from those in nonsupplemented men: 9.52 +/- 2.57 and 11.31 +/- 2.74 mg/kg, respectively. Nonsupplemented women showed a significantly (P < 0.05) greater decline in iron stores than did supplemented women: 13.09 +/- 2.46 and 10.60 +/- 4.15 mg/kg, respectively. Mean maximal iron absorption was approximately 4.10 mg/d for men and approximately 3.55 mg/d for women regardless of iron intake.