Racial differences of hemoglobin concentration: measurements of iron, copper, and zinc

Nutritional surveys have demonstrated that Hb levels in blacks are consistently lower than in whites. This difference does not appear to be related to socioeconomic dietary differences, or differences of hereditary disorders such as sickle cell disease. We studied 47 black and 63 white subjects drawn from hospital employees. Mean Hb of black men was 0.9 g/dl less than that of white men. Mean Hb of black women was 0.5 g/dl less than that of white women. This difference was not associated with differences of serum iron, iron binding capacity, or transferrin saturation. Ferritin values of white women were significantly less than values observed in white men, but similar differences were not observed between black men and women. The explanation for this is unclear although may be related to sample size or differences of menstrual status. Copper levels were lower in white men than in any other group, and zinc levels were essentially similar between racial groups. The red blood cells of blacks were also smaller than those of whites. This difference could not be explained by disordered Hb synthesis. These observations confirm that Hb concentrations in both black men and women are lower than in their white counterparts. This difference cannot be explained by differences in iron, copper, or zinc nutriture. Further, measurements of Hb in nutritional survey populations reflect iron status as only one of several variables and should not be used as the only assessment of iron nutrition.