Iron Isotope Signature in Red Blood Cell Samples from Japanese Female Donors of Various Ages

Abstract

We have measured δ56Fe/54Fe and δ57Fe/54Fe values in red blood cell (RBC) samples collected from male and female donors of various ages. To achieve this, effects of both Fe recovery through chemical separation procedures and Fe oxidation state in solutions for analysis on the measured Fe isotope ratios were rigorously evaluated. The resulting Fe isotope ratios (56Fe/54Fe and 57Fe/54Fe) in RBCs from female donors were significantly higher than those from male donors, suggesting that Fe isotopic composition in human RBCs can be different between male and female, as reflected by the inherent difference in Fe absorption efficiency from the diet. Regarding RBC samples from female donors, Jaouen and Balter (Am J Phys Anthropol 153:280–285, 2014) were first to report changes in Fe isotope signature in elderly donors of European population. This can be explained by possible changes in Fe absorption efficiency due to menopause. This is not true for the Japanese females. Our Fe isotope data showed that Fe isotope data for young females (δ56Fe/54Fe = −2.65 ± 0.34 ‰, δ57Fe/54Fe = −3.90 ± 0.53 ‰; 2SD, n = 18) did not vary significantly from elderly donors (δ56Fe/54Fe = −2.51 ± 0.49 ‰, δ57Fe/54Fe = −3.68 ± 0.73 ‰; 2SD, n = 10). Obvious discrepancy in the difference of the Fe isotope signature between Japanese and European elderly female donors can be explained by the differences in food culture or Fe nutritional status. In this study, the possible linkage between Fe isotope ratios and nutritional status of donors is discussed on the basis of the Fe isotope signature.