Vitamin D in northern latitudes: Intake and status in Icelandic children

• Main Author: Þórisdóttir, Birna
• Other Authors: Ingibjörg Gunnarsdóttir og Bryndís Eva Birgisdóttir, Matvæla- og næringarfræðideild (HÍ), Faculty of Food Science and Nutrition (UI), Heilbrigðisvísindasvið (HÍ), School of Health Sciences (UI), Háskóli Íslands, University of Iceland
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Iceland, School of Health Sciences, Faculty of Food Science and Nutrition 2018
• Subjects: Infant; Child; Vitamin D; Nutrition policy; Public health; Ungbörn; Börn; D vítamín; Næringarfræði; Næringarstefna; Doktorsritgerðir; Iceland
• Online Access: https://hdl.handle.net/20.500.11815/919

Background: Adequate nutrition in childhood is essential for growth, development and health. Vitamin D supplement use is recommended in Iceland, starting in infancy. Little information exists on the vitamin D status of Icelandic infants and children. Vitamin D has been suggested to affect the development of sensitization to food allergens and food allergy. Aim: To study adherence to dietary guidelines among 6-year-old children (paper I), their vitamin D intake and vitamin D status at 12 months and 6 years (papers II and III) and compare vitamin D and feeding in infancy between 6-year-old children IgE-sensitized to food allergens and non-sensitized children (paper IV). Methods: The study population is a nationally representative Icelandic cohort of infants born in 2005, followed up at 6 years of age. Three-day weighed food records were kept at 9 months (n=196), 12 months (n=170) and 6 years (n=162). Total vitamin D intake was calculated from both diet and supplements. Further infant nutrition data was collected by dietary history from birth to 5 months and by monthly 1-day food records at 5-8 and 10-11 months of age. Serum 25-hydroxyvitamin D (25(OH)D) was measured at 12 months (n=76) and 6 years (n=139) and serum-specific IgE-antibodies against food at 6 years (n=144). Cut-off values for vitamin D deficiency, insufficiency, sufficiency and possibly adversely high levels were set at 25(OH)D <30 nmol/L, 30-50 nmol/L, >50 nmol/L and >125 nmol/L, respectively. The cut-off value for sensitization was set at specific IgE ≥0.35 kUA/L. Results: Adherence to dietary guidelines varied among 6-year-old children but was poor in general. A quarter, or less, of the children followed the guidelines for fruit and vegetables, fish, wholegrain bread and other fiber-rich cereals and vitamin D supplements. The food intake was mirrored in a non-optimal distribution of macronutrients, fiber and salt intake. Vitamin and mineral density of the diet seemed however adequate, except for vitamin D. Supplements (fish liver oil or ...