title: Vitamin D deficiency in Malaysian adolescents aged 13 years: findings from the Malaysian Health and Adolescents Longitudinal Research Team study (MyHeARTs).
abstract: To determine the prevalence of vitamin D deficiency (<37.5 nmol/L) among young adolescents in Malaysia and its association with demographic characteristics, anthropometric measures and physical activity.
  
  
  
  This is a cross-sectional study among Form 1 (year 7) students from 15 schools selected using a stratified random sampling design. Information regarding sociodemographic characteristics, clinical data and environmental factors was collected and blood samples were taken for total vitamin D. Descriptive and multivariable logistic regression was performed on the data.
  
  
  
  National secondary schools in Peninsular Malaysia.
  
  
  
  1361 students (mean age 12.9±0.3 years) (61.4% girls) completed the consent forms and participated in this study. Students with a chronic health condition and/or who could not understand the questionnaires due to lack of literacy were excluded.
  
  
  
  Vitamin D status was determined through measurement of sera 25-hydroxyvitamin D (25(OH)D). Body mass index (BMI) was classified according to International Obesity Task Force (IOTF) criteria. Self-reported physical activity levels were assessed using the validated Malay version of the Physical Activity Questionnaire for Older Children (PAQ-C).
  
  
  
  Deficiency in vitamin D was seen in 78.9% of the participants. The deficiency was significantly higher in girls (92.6%, p<0.001), Indian adolescents (88.6%, p<0.001) and urban-living adolescents (88.8%, p<0.001). Females (OR=8.98; 95% CI 6.48 to 12.45), adolescents with wider waist circumference (OR=2.64; 95% CI 1.65 to 4.25) and in urban areas had higher risks (OR=3.57; 95% CI 2.54 to 5.02) of being vitamin D deficient.
  
  
  
  The study shows a high prevalence of vitamin D deficiency among young adolescents. Main risk factors are gender, ethnicity, place of residence and obesity.
authors.affiliation: Faculty of Medicine, Centre for Population Health (CePH), University of Malaya, Kuala Lumpur, Malaysia Faculty of Medicine, Department of Social and Preventive Medicine, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Nabilla
authors.initials: N
authors.lastname: Al-Sadat
authors.affiliation: Faculty of Medicine, Centre for Population Health (CePH), University of Malaya, Kuala Lumpur, Malaysia Faculty of Medicine, Department of Social and Preventive Medicine, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Hazreen Abdul
authors.initials: HA
authors.lastname: Majid
authors.affiliation: Faculty of Medicine, Centre for Population Health (CePH), University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Pei Ying
authors.initials: PY
authors.lastname: Sim
authors.affiliation: Faculty of Medicine, Centre for Population Health (CePH), University of Malaya, Kuala Lumpur, Malaysia Faculty of Medicine, Department of Social and Preventive Medicine, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Tin Tin
authors.initials: TT
authors.lastname: Su
authors.affiliation: Faculty of Medicine, Centre for Population Health (CePH), University of Malaya, Kuala Lumpur, Malaysia Faculty of Medicine, Department of Social and Preventive Medicine, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Maznah
authors.initials: M
authors.lastname: Dahlui
authors.affiliation: Faculty of Medicine, Centre for Population Health (CePH), University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Mohd Fadzrel
authors.initials: MF
authors.lastname: Abu Bakar
authors.affiliation: Faculty of Medicine, Centre for Population Health (CePH), University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Najat
authors.initials: N
authors.lastname: Dzaki
authors.affiliation: Family Health Development Division, Ministry of Health Malaysia, Putrajaya, Malaysia.
authors.forename: Saidatul
authors.initials: S
authors.lastname: Norbaya
authors.affiliation: Centre for Public Health, Queen's University Belfast, Royal Victoria Hospital, Belfast, UK.
authors.forename: Liam
authors.initials: L
authors.lastname: Murray
authors.affiliation: Centre for Public Health, Queen's University Belfast, Royal Victoria Hospital, Belfast, UK.
authors.forename: Marie M
authors.initials: MM
authors.lastname: Cantwell
authors.affiliation: Faculty of Medicine, Department of Paediatrics, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Muhammad Yazid
authors.initials: MY
authors.lastname: Jalaludin
mesh_terms: D000293:Adolescent; D044466:Asian People; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008296:Malaysia / Q000453:epidemiology; D008297:Male; D009765:Obesity / Q000453:epidemiology*; D015995:Prevalence; D057566:Self Report; D017678:Sex Distribution; D012737:Sex Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: PREVENTIVE MEDICINE; PUBLIC HEALTH; SOCIAL MEDICINE