title: Effect of Food and Vitamin D Supplements on the Serum 25(OH)D₃ Concentration in Children during Winter Months.
abstract: OBJECTIVE
  To determine the contribution of food and vitamin D supplements on the serum 25-hydroxyvitamin D₃ (25(OH)D₃) concentration between October and April in a northern country (almost absent vitamin D synthesis by sunlight).
  
  
  METHODS
  Children aged 1-18 years were selected who visited the general pediatrician with a complaint whereby serum 25(OH)D₃ concentration was determined. The intake of vitamin D was calculated based on a dietary questionnaire.
  
  
  RESULTS
  51.1% of the 174 children had a serum 25(OH)D₃ concentration below 50 nmol/L, 9.2% had a serum 25(OH)D₃ concentration below 30 nmol/L. Adolescents showed lower concentrations compared to younger children. There was a positive correlation between the total amount of vitamin D obtained from food and the serum 25(OH)D₃ concentration (r= 0.218,p= 0.004). The intake of milk contributed more to the serum 25(OH)D₃ concentration compared to the intake of artificial supplementation, butter or fish.
  
  
  CONCLUSIONS
  In the absence of vitamin D synthesis by sunlight, vitamin D obtained from food has a significant influence on the serum 25(OH)D₃ concentration in children. Vitamin D supplements can be described as trivial. This means we should pay more attention to food as a natural source of vitamin D.
authors.affiliation: Hospital Group Twente, Geerdinksweg 141, 7555 DL Hengelo, The Netherlands. e.gaagvander@zgt.nl.
authors.forename: Ellen
authors.initials: E
authors.lastname: van der Gaag
authors.affiliation: Medical School University of Groningen, Hanzeplein 1, Groningen, The Netherlands. l.brekhoff@student.rug.nl.
authors.forename: Lisanne
authors.initials: L
authors.lastname: Brekhoff
keywords: children; dietary vitamin D; nutrients; vitamin D deficiency; vitamin D supplements