Iron status at 12 months of age — effects of body size, growth and diet in a population with high birth weight

Abstract

Objective: To investigate effects of growth and food intake in infancy on iron status at the age of 12 months in a population with high birth weight and high frequency of breast-feeding. Design: In a longitudinal observational study infants' consumption and growth were recorded. Weighed 2 day food records at the ages of 6, 9 and 12 months were used to analyse food and nutrient intake. Setting: Healthy-born participants were recruited from four maternity wards. Blood samples and growth data were collected from healthcare centres and food consumption data at home. Subjects: Newborn infants (n ¼ 180) were selected randomly according to the mother's domicile and 77% (n ¼ 138) participated, of them, 83% (n ¼ 114), or 63% of original sample, came in for blood sampling. Results: Every fifth child was iron-deficient (serum ferritin < 12 mg=l and mean corpuscular volume < 74 fl) and 2.7% were also anaemic (Hb < 105 g=l). Higher weight gain from 0 to 12 months was seen in infants who were iron-deficient at 12 months (6.7 AE 0.9 kg) than in non-iron-deficient infants (6.2 AE 0.9 kg) (P ¼ 0.050). Serum transferrin receptors at 12 months were positively associated with length gain from 0 to 12 months (adjusted r 2 ¼ 0.14; P ¼ 0.045) and mean corpuscular volume negatively to ponderal index at birth (adjusted r 2 ¼ 0.14; P ¼ 0.019) and 12 months (adjusted r 2 ¼ 0.17; P ¼ 0.006). Irondeficient infants had shorter breast-feeding duration (5.3 AE 2.2 months) than non-iron-deficient (7.9 AE 3.2 months; P ¼ 0.001). Iron status indices were negatively associated with cow's milk consumption at 9 -12 months, significant above 460 g=day, but were positively associated with iron-fortified breakfast cereals, fish and meat consumption. Conclusions: In a population of high birth weight, iron deficiency at 12 months is associated with faster growth and shorter breast-feeding duration from 0 to 12 months of age. The results suggest that a diet of 9 -12-month-olds should avoid cow's milk above 500 g=day and include fish, meat and iron-fortified breakfast cereals to improve iron status.

Iron status in 2-year-old Icelandic children and associations with dietary intake and growth

“…A gender difference in the iron status was not seen in the present study, in contrast to previous findings in Icelandic 1-y-olds (Thorsdottir et al, 2003), where boys had significantly worse iron status and were more likely to be irondeficient than girls. Domellof et al (2002) concluded from their study of 9-month-old children, that difference in SF and MCV values was to be expected between boys and girls due to genetic or hormonal variances and sex-specific cutoffs for these indices might therefore be needed.…”

“…These are approximately half of the percentages seen in Icelandic 1-y-olds, with the same criteria used for defining iron deficiency and iron-deficiency anaemia, also fewer 2-y-olds had depleted iron stores (SFo12 mg/ l), or 27%, compared to 41% of 1-y-old children (Thorsdottir et al, 2003). However, the present findings show slightly worse iron status than observed in other recent studies of children in this age group from other Nordic countries.…”

“…A negative association between cow's milk consumption and iron status is well documented in younger children (Tunnessen & Oski, 1987), and also in this age group (Lawson et al, 1998;Bramhagen & Axelsson, 1999;Thane et al, 2000). In the study of Icelandic 1-y-olds, the effect of cow's milk on iron status was not seen until the cow's milk consumption had reached 500 g/day (Thorsdottir et al, 2003), and in the present study a similar difference was observed between those consuming more than 500 g/day and those consuming less. High consumption of cow's milk might displace foods from other food groups in the diet, as seen with cow's milk consumption 4400 g/day in the NDNS study (Thane et al, 2000), but the change in iron status indices seen at the 500 g/day mark in Table 3 might indicate an inhibiting effect of a high dose of cow's milk on the iron status, probably by some components of cow's milk.…”

“…Birth weight has been positively associated with the iron status at 12 months (Persson et al, 1998) and even up to 18 months (Sherriff et al, 1999), and fast growth during the first year has been negatively associated with the iron status (Michaelsen et al, 1995;Sherriff et al, 1999;Thorsdottir et al, 2003). Influence of birth weight and growth rate on the iron status at 2 y of age have not been documented.…”

“…However, dietary intake of iron have at best been vaguely related to the iron status in infants and children, while intakes of foods and nutrients known to affect nonhaem and also to some extent haem iron bioavailability have shown stronger relation to the iron status. The strongest influence has been seen from cow's milk consumption, which has been negatively associated with the iron status in young children (Thane et al, 2000;Thorsdottir et al, 2003).…”