title: Influence of Ultraviolet Radiation on the Association between 25-Hydroxy Vitamin D Levels and Cardiovascular Risk Factors in Obesity.
abstract: OBJECTIVE
  To establish if the correction with estimates of ultraviolet (UV) exposure influences the association between 25-OH-vitamin D (25OHD) levels and metabolic variables.
  
  
  METHODS
  A cross-sectional study was performed in 575 obese children and adolescents (>6 years of age) in a tertiary referral center. Cardiovascular risk factors were measured. The estimate of UV exposure was evaluated by 3 methods: (1) season; (2) mean of UV radiation (UVR); and (3) mean of UV index (UVI). UVR and UVI were considered at 1 (UVR 1 month prior to testing [UVR1], UVI 1 month prior to testing [UVI1]) or 3 (UVR 3 months prior to testing [UVR3], UVI 3 months prior to testing [UVI3]) months prior to testing. All analyses were corrected for confounders (sex, age, puberty, body mass index, waist circumference, the inclusion and exclusion of estimates of UV exposure).
  
  
  RESULTS
  The 25OHD levels were associated with seasons, UVR1, UVR3, UVI1, and UVI3, and best associations with UVR3 and UVI3. In all models, total cholesterol, low-density lipoprotein cholesterol and triglycerides were negatively associated with 25OHD levels. The strength of the association increased with no correction, correction for seasons, UVR, and UVI. UVR3 and UVI3 performed better than UVR1 and UVI3.
  
  
  CONCLUSIONS
  Higher lipid concentrations were associated with low 25OHD levels in obese children and adolescents with the power of the association dependent on the estimates of UVR. As the mean values 3 months prior to testing for both UVR and UVI determined the best associations, the interval of the steady state time of 25OHD levels could be preferentially used in the metabolic studies. Controlling for an estimate of UVR is important to decrease the heterogeneity of studies.
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy; Endocrinology, Department of Translational Medicine, Università del Piemonte Orientale "A. Avogadro," Novara, Italy. Electronic address: flavia.prodam@med.uniupo.it.
authors.forename: Flavia
authors.initials: F
authors.lastname: Prodam
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Zanetta
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Ricotti
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Agostina
authors.initials: A
authors.lastname: Marolda
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Enza
authors.initials: E
authors.lastname: Giglione
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Monzani
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Gillian Elisabeth
authors.initials: GE
authors.lastname: Walker
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Rampone
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Castagno
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Simonetta
authors.initials: S
authors.lastname: Bellone
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Petri
authors.affiliation: Endocrinology, Department of Translational Medicine, Università del Piemonte Orientale "A. Avogadro," Novara, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Aimaretti
authors.affiliation: Division of Pediatrics, Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy.
authors.forename: Gianni
authors.initials: G
authors.lastname: Bona
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D002648:Child; D008078:Cholesterol, LDL / Q000097:blood; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007558:Italy; D008055:Lipids / Q000097:blood; D008297:Male; D063766:Pediatric Obesity / Q000097:blood / Q000150:complications*; D012044:Regression Analysis; D012307:Risk Factors; D062606:Tertiary Care Centers; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D008078:Cholesterol, LDL; D008055:Lipids; D014807:Vitamin D; C104450:25-hydroxyvitamin D