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Gender-related differences in iron absorption by preadolescent children
J C Woodhead1, J M Drulis, S E Nelson
1Department of Pediatrics, College of Medicine, University of Iowa, Iowa City 52242.
Insights
Girls aged Tanner stage 1 showed significantly higher iron absorption than boys, irrespective of meal content. This gender difference in iron uptake is not explained by body iron stores, suggesting hormonal influences.
Area of Science:
- Pediatric Nutrition
- Human Physiology
- Biochemistry
Background:
- Previous observations suggested potential gender differences in iron absorption among preadolescent children.
- Preadolescent children (Tanner stage 1) were the focus due to their distinct developmental stage.
Purpose of the Study:
- To investigate and quantify gender-related differences in iron absorption in preadolescent children.
- To explore potential factors, such as body iron stores, influencing these differences.
Main Methods:
- Two studies (A and B) were conducted using iron-58 (58Fe) as a stable isotope tracer.
- Study A involved administering ferrous sulfate with ascorbic acid to fasted children; Study B involved administering 58Fe-labeled breakfast.
- Erythrocyte incorporation of 58Fe was measured using inductively coupled plasma mass spectrometry.
Main Results:
- Girls demonstrated significantly higher erythrocyte incorporation of 58Fe compared to boys in both studies (Study A: 45.0% vs 35.2%; Study B: 24.7% vs 14.8%).
- These differences remained significant after adjusting for serum ferritin levels, indicating they are not solely due to variations in body iron stores.
- Serum ferritin concentrations were similar between genders, ruling out body iron stores as the primary explanation.
Conclusions:
- Preadolescent girls exhibit enhanced iron absorption compared to boys.
- Hormonal differences between genders in Tanner stage 1 are hypothesized to be the underlying factor driving this observed difference in iron absorption.
- Further research into hormonal influences on iron metabolism in this age group is warranted.
Abstract:
In a study of absorption of iron from meals by preadolescent children (Tanner stage 1), we had noted that erythrocyte incorporation of the extrinsic iron label was somewhat greater by girls than by boys. Although the difference was not significant, the observation seemed to warrant further study. Study A: A precisely determined quantity of ferrous sulfate enriched with the stable isotope 58Fe was given without food to 15 boys and 15 girls (Tanner stage 1) after an overnight fast and was immediately followed by a dose of 70 mg of ascorbic acid. 58Fe enrichment of the erythrocytes was determined by inductively coupled plasma mass spectrometry at baseline and 14 and 42 d after administration of the 58Fe dose. Geometric mean erythrocyte incorporation of the 58Fe label was 35.2% of intake by boys and 45.0% of intake by girls. The difference was significant (analysis of covariance with serum ferritin as covariate, p = 0.035). Study B: Fifteen boys and 15 girls (Tanner stage 1) were fed a breakfast labeled with 58Fe. Geometric mean erythrocyte incorporation of the 58Fe label was 14.8% of intake by boys and 24.7% of intake by girls. The difference was significant (analysis of covariance with serum ferritin as covariate, p = 0.004). Because serum ferritin concentrations were similar in boys and girls, the gender-related difference in iron absorption (as reflected by erythrocyte incorporation of the label) does not appear to be explained by a difference in body stores of iron. We hypothesize that hormonal differences between boys and girls in Tanner stage 1 favor iron absorption by girls.