Iron Stores of Breastfed Infants during the First Year of Life

Abstract

The birth iron endowment provides iron for growth in the first months of life. We describe the iron endowment under conditions of low dietary iron supply. Subjects were infants participating in a trial of Vitamin D supplementation from 1 to 9 months. Infants were exclusively breastfed at enrollment but could receive complementary foods from 4 months but not formula. Plasma ferritin (PF) and transferrin receptor (TfR) were determined at 1, 2, 4, 5.5, 7.5, 9 and 12 months. At 1 month PF ranged from 38 to 752 µg/L and was only weakly related to maternal PF. PF declined subsequently and flattened out at 5.5 months. PF of females was significantly higher than PF of males except at 12 months. TfR increased with age and was inversely correlated with PF. PF and TfR tracked strongly until 9 months. Iron deficiency (PF < 10 µg/L) began to appear at 4 months and increased in frequency until 9 months. Infants with ID were born with low iron endowment. We concluded that the birth iron endowment is highly variable in size and a small endowment places infants at risk of iron deficiency before 6 months. Boys have smaller iron endowments and are at greater risk of iron deficiency than girls.

Developmental Physiology of Iron Absorption, Homeostasis, and Metabolism in the Healthy Term Infant

“…Taken together, iron requirements during the first half of infancy depend greatly on the iron endowment of the infant at birth. This is supported by a recent study by Ziegler et al (35) who showed that infants who were exclusively breast-fed until 4 months of age and allowed to receive complementary foods but not infant formula from 4 to 9 months of age started to show signs of ID from 4 months and, with increasing prevalence, until 9 months of age. By 6 months of age, 5% of the infants had exhausted iron stores (ID).…”

“…Moreover, boys at 9 months of age had a higher risk of being classified with IDA than girls (38). Ziegler et al (35) also reported lower iron status of boys than of girls. The sex differences in mean corpuscular volume and zinc protoporphyrin concentrations may reflect normal physiological differences between genders.…”

Early deterioration of iron status among a cohort of Bolivian infants

“…Even in well-resourced populations (e.g., USA, Denmark, and Norway), Fer has been shown to decrease from birth through at least 6 months of age, as birth iron stores run out faster than they are replenished through diet (Hay et al, 2007; Kling, Roberts, & Widness, 1998; Michaelsen et al, 1995; Ziegler et al, 2014). Nonetheless, the (Fer-defined) ID prevalence observed in our cohort was higher than that observed in other Latin American populations (32% in 5-month-old Peruvian infants (Finkelstein et al, 2013); 26% in 6-month-old Brazilian infants (Marques et al, 2014)), although comparable with some other developing-country settings (59% in Nigerian 6-month-olds (Preziosi et al, 1997)).…”

“…However, the size of these stores at birth can vary, and given the low intake of iron through breast milk in the first months of life, birth stores may be an important determinant of later risk of iron deficiency (Burke et al, 2014). Although multiple studies have gathered data on iron status on infants at different ages (Capozzi, Russo, Bertocco, Ferrara, & Ferrara, 2010; Domellof, Dewey, Lonnerdal, Cohen, & Hernell, 2002; Finkelstein, O’Brien, Abrams, & Zavaleta, 2013; Marques, Taddei, Lopez, & Braga, 2014; Michaelsen, Milman, & Samuelson, 1995; Olaya, Lawson, & Fewtrell, 2013; Preziosi et al, 1997; Sherriff, Emond, Hawkins, & Golding, 1999), few have provided data for healthy infants followed from breastfeeding age through complementary food introduction and up to 1 year of life (Hay et al, 2007; Willows, Dewailly, & Gray-Donald, 2000; Ziegler, Nelson, & Jeter, 2014). These published studies suggest that iron status declines significantly over the first year of life, leading to ID in vulnerable populations.…”

Modern Complementary Foods in the Prevention of Allergic Diseases: Prospective Study Results

“…Это согласуется с недавно опубликованными дан-ными E. E. Ziegler и соавт. [12], а также данными нашего исследования, проведенного в 2012 г., и обосновывает необходимость введения обогащенной железом каши промышленного выпуска как первого продукта прикорма и мясного пюре с возраста 6 мес.…”