title: Vitamin D status and its determinants during autumn in children at northern latitudes: a cross-sectional analysis from the optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) School Meal Study.
abstract: Sufficient summer/autumn vitamin D status appears important to mitigate winter nadirs at northern latitudes. We conducted a cross-sectional study to evaluate autumn vitamin D status and its determinants in 782 Danish 8-11-year-old children (55°N) using baseline data from the Optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) School Meal Study, a large randomised controlled trial. Blood samples and demographic and behavioural data, including 7-d dietary recordings, objectively measured physical activity, and time spent outdoors during school hours, were collected during September-November. Mean serum 25-hydroxyvitamin D (25(OH)D) was 60·8 (sd 18·7) nmol/l. Serum 25(OH)D levels ≤50 nmol/l were found in 28·4 % of the children and 2·4 % had concentrations <25 nmol/l. Upon multivariate adjustment, increasing age (per year) (β -2·9; 95 % CI -5·1, -0·7 nmol/l), female sex (β -3·3; 95 % CI -5·9, -0·7 nmol/l), sampling in October (β -5·2; 95 % CI -10·1, -0·4 nmol/l) and November (β -13·3; 95 % CI -17·7, -9·1), and non-white ethnicity (β -5·7; 95 % CI -11·1, -0·3 nmol/l) were negatively associated with 25(OH)D (all P<0·05). Likewise, immigrant/descendant background was negatively associated with 25(OH)D, particularly in females (β -16·3; 95 % CI -21·9, -10·7) (P<0·001) (P interaction=0·003). Moderate-to-vigorous physical activity (MVPA) (min/d) (β 0·06; 95 % CI 0·01, 0·12), outdoor walking during school hours (min/week) (β 0·4; 95 % CI 0·1, 0·6) and intake of vitamin D-containing supplements ≥3 d/week (β 8·7; 95 % CI 6·4, 11·0) were positively associated with 25(OH)D (all P<0·05). The high proportion of children with vitamin D status below the recommended sufficiency level of 50 nmol/l raises concern as levels expectedly drop further during winter months. Frequent intake of vitamin D supplements was strongly associated with status. MVPA and outdoor activity during school hours should be investigated further in interventions to improve autumn vitamin D status in children at northern latitudes.
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Rikke A
authors.initials: RA
authors.lastname: Petersen
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Camilla T
authors.initials: CT
authors.lastname: Damsgaard
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Stine-Mathilde
authors.initials: SM
authors.lastname: Dalskov
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Louise B
authors.initials: LB
authors.lastname: Sørensen
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Mads F
authors.initials: MF
authors.lastname: Hjorth
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Ritz
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Louise
authors.identifier: http://orcid.org/0000-0003-4310-9332
authors.initials: L
authors.lastname: Kjølbæk
authors.affiliation: 2Division of Nutrition,The National Food Institute,Technical University of Denmark,Mørkhøj Bygade 19,2860 Søborg,Denmark.
authors.forename: Rikke
authors.initials: R
authors.lastname: Andersen
authors.affiliation: 2Division of Nutrition,The National Food Institute,Technical University of Denmark,Mørkhøj Bygade 19,2860 Søborg,Denmark.
authors.forename: Inge
authors.initials: I
authors.lastname: Tetens
authors.affiliation: 3Department of Clinical Biochemistry,Section of Molecular Diagnostics,Aalborg University Hospital,Hobrovej 18-22,9000 Aalborg,Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Krarup
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Arne
authors.initials: A
authors.lastname: Astrup
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Kim F
authors.initials: KF
authors.lastname: Michaelsen
authors.affiliation: 1Department of Nutrition,Exercise and Sports, Faculty of Science,University of Copenhagen,Rolighedsvej 26,1958 Frederiksberg C,Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Mølgaard
mesh_terms: D000367:Age Factors; D000818:Animals; D002648:Child; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D004032:Diet; D019587:Dietary Supplements; D005006:Ethnicity; D005260:Female; D005399:Fishes; D006304:Health Status; D006801:Humans; D008297:Male; D009043:Motor Activity; D009752:Nutritional Status; D011627:Puberty; D012574:Schools; D012621:Seasons; D012737:Sex Factors; D013472:Sunlight; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: Children; DHA docosahexanoic acid; Determinants; EI energy intake; MVPA moderate-to-vigorous physical activity; Northern latitudes; OPUS optimal well-being; Vitamin D; development and health for Danish children through a healthy New Nordic Diet