Iron Stores Investigated in Women, Elderly

ATLANTA & BOSTON--In two studies appearing in the December edition of the American Journal of Clinical Nutrition, researchers reported on iron stores, reproductive-aged women and the elderly. In the first study, researchers from Emory University, Atlanta, investigated the association between iron stores and cardiovascular disease (CVD) in women aged 20 to 49 years old (76:1256-60, 2002). Extrapolating data taken from the third National Health and Nutrition Examination Survey (1988-1994), lead researcher Usha Ramakrishnan, Ph.D., and colleagues reported iron levels were positively associated with CVD among non-Hispanic white, non-Hispanic black and Mexican American women, especially in terms of glucose and lipid metabolism.

The second study raised the question of whether high iron stores increased chronic disease risk in the elderly. Data that was taken from the Framingham Heart Study cohort and included 614 subjects aged 68 to 93 years old indicated that highly bioavailable forms of iron, either from taking more than 30 mg/d as an iron supplement or from red meat, promoted high iron stores. However, foods containing phytate, such as whole grains, decreased these stores (76:1375-84, 2002). Interestingly, lead researcher Diana J. Fleming, Ph.D., out of Tufts University, Boston, and colleagues reported intake of fruit containing vitamin C (more than 21 servings per week) was found to enhance nonheme-iron absorption.

They also reported that both heme- and nonheme-iron intake were found to be significantly associated with an increased risk of myocardial infarction (caused by blockages in coronary arteries). And because red meat intake was linked to a higher risk of high iron stores, many elderly Americans consuming a Western diet may be harboring high iron stores.

A causal relationship between excess body iron and heart disease risk is controversial, the Fleming et al wrote, but further research should be conducted to see whether high iron stores are a factor in chronic disease. "[M]odifiying dietary patterns and avoiding iron-containing dietary supplements could be helpful in decreasing the risk of developing high iron stores and, thus, the risk of developing disease," Fleming and his colleagues concluded.

According to Max Motyka, Ph.D., director of the human products division at Clearfield, Utah-based Albion Advanced Nutrition, linking high iron stores to chronic disease risk is a chicken-or-the-egg issue. "The iron in storage comes out in the blood stream and doesn't do anything to cause an event, but is the result of the event," Motyka said. "Your body regulates the storage of iron." He added that if a manufacturer were to start a whole line of iron-free vitamin/mineral supplements, it would be doing a disservice to those buying it. In the long run, the people with iron deficiencies far outweigh those with high iron stores.

In an editorial appearing alongside the Fleming study, John Beard, Ph.D., from Pennsylvania State University, University Park, reported that the potential link between chronic disease risk and high iron levels is far from conclusive (76:1189-90, 2002). "Considering the heated debate on the causal relationship of dietary iron intake and iron accumulation with disease processes, these data are very sparse," he wrote. "It may prove to be informative to conduct the same analyses on data collected from these subjects during their younger years and compare the results with those of the present study."

The two studies can be found at www.faseb.org/ajcn/Dec2002/13086.Ramakrishnan1.PDF and www.faseb.org/ajcn/Dec2002/13508.Fleming.PDF.