Bouncing back from giving blood can take months

People who donate blood can take months to recoup their stores of iron, a new study shows. But the process moves much faster if they take iron supplements afterward, scientists from the National Heart, Lung and Blood Institute and elsewhere report in the Feb. 10 JAMA.

In the study, 96 people randomly assigned to get a daily iron supplement for 24 weeks after giving blood regained at least 80 percent of their lost iron in less than five weeks, on average. But it took the 97 people who didn’t get the pill 11 to 23 weeks on average to recover, depending on whether they started with high or low iron levels. The researchers measured iron through a proxy called ferritin, a protein that stores and releases iron in cells.

Iron is needed to make hemoglobin that enables red blood cells to shuttle oxygen around the body. The findings help to explain why up to one-third of regular blood donors develop iron deficiency, which can cause fatigue, irritability and other symptoms.

In the United States, healthy people are permitted to donate blood every eight weeks. The Food and Drug Administration is weighing whether this interval should be longer, the researchers note.