To investigate, Dr. Jack M. Guralnik, from the National Institutes of Health in Bethesda, Maryland, and colleagues analyzed data from non-institutionalized subjects represented in the third National Health and Nutrition Examination Survey (NHANES III).

A steady increase in anemia rates was noted after age 50, the researchers report in the medical journal Blood.

In the 50- to 64-year-old age group, 4.4 percent of men and 6.8 percent of women were anemic. By 85 years of age, these percentages had risen to 26.1 percent and 20.1 percent, respectively.

Roughly one in ten individuals 65 years of age and older were anemic, the investigators point out.

As for the cause of anemia in older persons, the team found that nutrient deficiency and anemia related to chronic inflammation or chronic renal disease were each implicated in one third of cases - while the remainder were unexplained.

Most cases of anemia were mild; more serious deficiencies affected just 2.8 percent of women and 1.6 percent of men.

"It is important that anemia in older persons receive adequate attention in clinical practice and not be considered simply a normal part of aging," the authors note.

In a related editorial, Dr. Stanley L. Schrier, from Stanford University School of Medicine in California, notes that "further studies are needed to determine if correction of the mild anemia ... will improve the outlook of affected patients."