Aging has some effect on bone marrow and blood cells. The amount of fat in the marrow increases with age, which means there is less cell-producing marrow. While this decrease generally does not cause problems, it may when the body experiences an increased demand for blood cells: the marrow of an older person may be less able to meet those increased demands. Anemia is the most common result.
Last full review/revision August 2006 by Eugene P. Frenkel, MD