title: Association between vitamin D status and physical function in the severely obese.
abstract: BACKGROUND
  Mortality is 85% higher in severely obese subjects (body mass index [BMI] > 40 kg/m(2)) than in subjects with a healthy BMI; poor physical function may be contributory. Hypovitaminosis D is common in obese subjects and is associated with physical dysfunction in the elderly.
  
  
  OBJECTIVE
  We determined the relationship between vitamin D status and physical function in severely obese subjects.
  
  
  METHODS
  We conducted a clinic-based, cross-sectional study of severely obese subjects. Participants were stratified into three groups according to the Institute of Medicine (IOM) vitamin D status categorization.
  
  
  METHODS
  We compared levels of self-reported activity and times taken to walk 500 m and to ascend and descend a 17-cm step 50 times.
  
  
  RESULTS
  We recruited 252 subjects (age, 43.7 ± 11.2 y; BMI, 50.7 ± 9.7 kg/m(2)); 25-hydroxyvitamin D (25OHD) concentrations were less than 30 nmol/L in 109 participants. Participants with a 25OHD > 50 nmol/L, compared to those with a 25OHD < 30 nmol/L, had the highest activity levels (3.1 ± 3.4 h/wk versus 1.5 ± 2.5 h/wk; P = .015) and the shortest 500-m walk times (6.2 ± 1.1 min versus 7.4 ± 1.5 min; P = .003). Serum 25OHD concentrations had a weakly positive association with activity level (r = 0.19; P = .008) and a moderately negative association with 500-m walk time (r = -0.343; P < .001).
  
  
  CONCLUSIONS
  Vitamin D status had a significant relationship with physical activity and physical function in this cohort of severely obese subjects. Low activity levels are likely to perpetuate the problem of hypovitaminosis D due to less time spent outdoors. Studies exploring the effects of vitamin D supplementation in this population are warranted.
authors.affiliation: Weight Management Service (T.A., A.K., E.O., C.D., C.W., D.O.), St Columcille's Hospital, Loughlinstown, County Dublin, Ireland; Obesity Research Group, Education and Research Centre (T.A., A.K., C.W., D.O.), Department of Endocrinology (T.A., A.K., C.W., M.J.M., D.O.), and Metabolism Laboratory (M.K., M.J.M.), St Vincent's University Hospital, Elm Park, Dublin 4, Ireland.
authors.forename: T
authors.initials: T
authors.lastname: Ahern
authors.forename: A
authors.initials: A
authors.lastname: Khattak
authors.forename: E
authors.initials: E
authors.lastname: O'Malley
authors.forename: C
authors.initials: C
authors.lastname: Dunlevy
authors.forename: M
authors.initials: M
authors.lastname: Kilbane
authors.forename: C
authors.initials: C
authors.lastname: Woods
authors.forename: M J
authors.initials: MJ
authors.lastname: McKenna
authors.forename: D
authors.initials: D
authors.lastname: O'Shea
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009752:Nutritional Status; D009767:Obesity, Morbid / Q000097:blood* / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology; D055815:Young Adult
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D