Deliberations and Evaluations of the Approaches, Endpoints and Paradigms for Iron Dietary Recommendations

Abstract

Iron deficiency severe enough to cause anemia is associated with significant morbidity while uncontrolled iron absorption which occurs in disorders such as hereditary hemochromatosis causes multiorgan failure and early death. Preliminary data from the Third National Health and Nutrition Examination Survey demonstrate that the prevalence of iron deficiency anemia in the United States is now very low. This implies that the current iron consumption is adequate for most individuals. An important unresolved question relates to the necessity for further reducing the prevalence of iron deficiency without anemia. More information is required to determine whether this lesser degree of iron deficiency is harmful. Recent survey data indicate that concomitantly with the reduced prevalence of iron deficiency there has been a rise in serum ferritin concentrations in American men and postmenopausal women. These findings have led to concern about the effectiveness of the physiological mechanisms for limiting storage accumulation in normal individuals and carriers of the hemochromatosis gene when dietary iron content is high. Furthermore, recent epidemiological observations suggest that a modest increase in iron stores (in a range previously considered safe) is a possible risk factor for ischemic heart disease and cancer; however, a causal relationship remains to be proven. Nonetheless, because there is no known benefit of high iron storage status, it seems prudent to avoid further increases in and possibly to reduce the dietary iron intake of men and postmenopausal women. Mean intake in these groups exceeds the current RDA by a significant margin. Therefore, the sources of dietary iron as well as other factors contributing to high serum ferritin values have to be defined. Also, efforts should be made to increase the awareness of professionals and the public about the possible risks of excessive dietary iron. The complexity of the Western diet and an incomplete understanding of all of the factors affecting serum ferritin concentrations make it very difficult to specify a safe upper range for daily iron intake at the present time.