Janet R Hunt1, Carol Ann Zito, LuAnn K Johnson. 1. US Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, ND 58202-9034, USA. janetrhunt@gmail.com
Abstract
BACKGROUND: Iron excretion measured by isotope dilution has been a primary basis for the factorial derivation of recommendations for iron intake, but the results have been available for men only. OBJECTIVE: The objective of this study was to confirm iron excretion measurements in healthy men and extend them to women. DESIGN: The turnover rate of 55Fe that had been administered > or =1 y earlier was determined from blood sampled semiannually for up to 3 y from 53 subjects in the community. Body iron was determined from hemoglobin, serum ferritin, and transferrin receptor. Complete menstrual collections were obtained from 13 women. RESULTS: The total median (range) iron excretion was 1.18 (0.11-2.07) mg/d for 29 men, 1.58 (0.65-4.88) mg/d for 19 menstruating women, and 0.99 (0.86-1.57) for 5 postmenopausal women. When hormonal contraceptive users were omitted, the median for 15 menstruating women increased to 1.66 mg/d. The distribution of iron excretion was normal for the men and postmenopausal women and was highly skewed for the menstruating women; menstrual iron accounted for 90% of the variation. Iron excretion was not strongly related to body weight. Body iron in menstruating women decreased somewhat (by 4.6%) in the men and tended to increase (by 1.5%) during the study. CONCLUSIONS: The results extend direct iron excretion measurements in men to include similar measurements in women. The results emphasize the wide range of iron excretion in humans, which results in a 40-fold range of requirements for absorbed iron. This trial was registered at clinicaltrials.gov as NCT00755105.
BACKGROUND:Iron excretion measured by isotope dilution has been a primary basis for the factorial derivation of recommendations for iron intake, but the results have been available for men only. OBJECTIVE: The objective of this study was to confirm iron excretion measurements in healthy men and extend them to women. DESIGN: The turnover rate of 55Fe that had been administered > or =1 y earlier was determined from blood sampled semiannually for up to 3 y from 53 subjects in the community. Body iron was determined from hemoglobin, serum ferritin, and transferrin receptor. Complete menstrual collections were obtained from 13 women. RESULTS: The total median (range) iron excretion was 1.18 (0.11-2.07) mg/d for 29 men, 1.58 (0.65-4.88) mg/d for 19 menstruating women, and 0.99 (0.86-1.57) for 5 postmenopausal women. When hormonal contraceptive users were omitted, the median for 15 menstruating women increased to 1.66 mg/d. The distribution of iron excretion was normal for the men and postmenopausal women and was highly skewed for the menstruating women; menstrual iron accounted for 90% of the variation. Iron excretion was not strongly related to body weight. Body iron in menstruating women decreased somewhat (by 4.6%) in the men and tended to increase (by 1.5%) during the study. CONCLUSIONS: The results extend direct iron excretion measurements in men to include similar measurements in women. The results emphasize the wide range of iron excretion in humans, which results in a 40-fold range of requirements for absorbed iron. This trial was registered at clinicaltrials.gov as NCT00755105.
Authors: Dominic J Hare; Manish Arora; Nicole L Jenkins; David I Finkelstein; Philip A Doble; Ashley I Bush Journal: Nat Rev Neurol Date: 2015-06-23 Impact factor: 42.937
Authors: Sean Lynch; Christine M Pfeiffer; Michael K Georgieff; Gary Brittenham; Susan Fairweather-Tait; Richard F Hurrell; Harry J McArdle; Daniel J Raiten Journal: J Nutr Date: 2018-06-01 Impact factor: 4.798