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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.

We examined 395 mtDNA control-region sequences from Greenlandic Inuit and Canadian Kitikmeot Inuit with the aim of shedding light on the migration history that underlies the present geographic patterns of genetic variation at this locus in the Arctic. In line with previous studies, we found that Inuit populations carry only sequences belonging to haplotype clusters A2 and D3. However, a comparison of Arctic populations from Siberia, Canada, and Greenland revealed considerable differences in the frequencies of these haplotypes. Moreover, large sample sizes and regional information about birthplaces of maternal grandmothers permitted the detection of notable differences in the distribution of haplotypes among subpopulations within Greenland. Our results cast doubt on the prevailing hypothesis that contemporary Inuit trace their all of their ancestry to so-called Thule groups that expanded from Alaska about 800-1,000 years ago. In particular, discrepancies in mutational divergence between the Inuit populations and their putative source mtDNA pool in Siberia/Alaska for the two predominant haplotype clusters, A2a and A2b, are more consistent with the possibility that expanding Thule groups encountered and interbred with existing Dorset populations in Canada and Greenland.

In a high-income country, adding a small amount of complementary food in addition to breast milk to infants' diets from 4 months of age does not affect growth rate between 4 and 6 months, but has a small and positive effect on iron status at 6 months. The biological importance of this finding remains to be determined.

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