Unrecognized iron deficiency can impair immunity in older women

Sep 29 2004

Iron deficiency, which can masquerade as routine, old-age symptoms, was found to impair measures of immunity from 28 percent to 50 percent in a group of seemingly healthy, well-nourished, homebound, older women, age 60 and above, in a Penn State study.

The study leader, Namanjeet Ahluwalia, associate professor of nutrition, said, "Iron deficiency in our study was associated with impairments on two measures of immunity at levels that may render older adults more vulnerable to infections."

"Older women can suffer iron deficiencies because of the effects of aging. It's best to be checked if you sense changes, such as being fatigued easily, breathlessness, attention problems or frequent infections," she added. "It's not necessarily aging and could be a problem related to undernutrition, specifically iron deficiency. However, iron supplementation should not be started without lab work and a doctor's order."

Ahluwalia will describe the study findings in a presentation at the Fourth European Congress on Nutrition and Health in the Elderly in France in November. Her results also are detailed in a paper, "Immune Function is Impaired in Iron-Deficient, Homebound, Older Women," published earlier this year in the American Journal of Clinical Nutrition. Her co-authors are Jianquin Sun, postdoctoral fellow; Deanna Krause, graduate student; Andrea Mastro, professor of microbiology and cell biology; and Gordon Handte, director, clinical laboratory, University Health Services.

The study included 72 women, 60 or older, living in three rural Pennsylvania counties who were receiving services, such as meals or assistance with activities of daily living, from the Office on Aging. All were considered healthy, free of inflammation and generally well-nourished.

Iron assessments on blood samples provided by the participants identified women as iron deficient if their iron stores were depleted and they had abnormal results on two or more other iron status tests.

Ahluwalia said, "Although half the iron-deficient women were anemic, the rate of iron deficiency we found was moderate. The subjects ranged from a few who were severely deficient and had low hemoglobin, to those who had normal hemoglobin and whose other tests were subnormal."

Cells from the blood samples of both the iron-sufficient and iron-deficient women were subjected to several tests of immune response. In one test, a type of white cell, called T-cells, was stimulated with two chemicals that simulate response to infection in the body. Normally, T-cells respond by multiplying when faced with such a challenge. In the iron-deficient women, the T-cells response was only 40 percent to 50 percent that of the iron-sufficient women.

In another test, granulocytes, another type of white blood cell, were challenged with bacteria. Granulocytes usually ingest bacteria and kill them with an oxidative burst. While the extent to which granulocytes ingested the bacteria did not differ significantly by iron status, the magnitude of the oxidative burst was 28 percent less in iron-deficient women, suggesting a potentially reduced capacity of these cells to kill bacteria.

"We are conducting a follow-up project to study the effects on immunity of correcting iron deficiency via supplements," Ahluwalia said. "We are currently recruiting women age 60 or above for that study."

The current study was supported by grants from the U.S. Department of Agriculture and the National Cattlemen's Beef Association.