While reports of inadequate vitamin D intakes among young children are widespread(1–Reference Hennessey, Browne and Kiely3), data on the prevalence of vitamin D inadequacy and deficiency are inconsistent. To date, there are few data on vitamin D status in young Irish children. We aimed to quantify vitamin D intake and serum 25-hydroxyvitamin D [25(OH)D] concentrations in children aged 2 years living in Ireland (51°N).
Serum 25(OH)D3, 25(OH)D2 and 3-epi-25(OH)D3 were analysed using UPLC-MS/MS in 742 children participating in the Cork BASELINE Birth Cohort Study. Non-consecutive, two-day weighed food diaries were collected in 468 children and 295 children had both a food diary and their 25(OH)D concentrations measured.
Mean (SD) total 25(OH)D concentrations were 63·4 (20·4) nmol/L [54·6 (20·0) in winter and 71·2 (17·5) nmol/L in summer]. During winter (Nov-Apr), 45·1 % were < 50 nmol/L, which decreased to 10·4 % in summer. The prevalence of vitamin D deficiency (< 30 nmol/L) was 4·6 % (8·6 % in winter, 1·0 % in summer). The C-3 epimer was present in all samples. The majority (98·9 %) of mothers were Caucasian and almost all (96·7 %) mothers reported applying sunscreen to their child's skin when they go out during the summer. With a mean daily vitamin D intake (MDI) of 3·5 µg/d, 96 % had intakes below the Estimated Average Requirement [EAR] of 10 µg/d (4), 78 % were < 5 µg/d and 13 % were < 1 µg/d. Children who did not use a supplement or consume a vitamin D-fortified food had an MDI of 1·2 µg/d. The highest intakes were among consumers of vitamin D-fortified formula (7·2 µg/d) and users of vitamin D-containing supplements (8·1 µg/d). While 94 % of children sampled during winter had intakes below the EAR, the corresponding prevalence < 40 nmol/L was 24 %, which is the threshold on which the EAR is based(4).
In conclusion, we show a low prevalence of vitamin D deficiency among Irish 2-year olds despite a high prevalence of inadequate vitamin D intakes, a high latitude and self-reported adherence to sun-safe recommendations. The current EAR may be too high for young children. Nevertheless, almost half of children had a 25(OH)D concentration < 50 nmol/L during winter, indicating the need for strategies to improve vitamin D intakes in this age-group.
This work was supported by the National Children's Research Centre. Ethical approval was granted by the Clinical Research Ethics Committee of the Cork Teaching Hospitals, ref ECM 5 (9) 01/07/2008 and the study is registered with the United States National Institutes of Health Clinical Trials Registry (http://www.clinicaltrials.gov), ID: NCT01498965. The study was conducted according to the guidelines laid down in the Declaration of Helsinki.
