title: Blood levels of vitamin D and health-functional status in asymptomatic individuals: a cross sectional study.
abstract: BACKGROUND
  Recently issued guidelines do not recommend screening for vitamin D deficiency in asymptomatic adults. The large range of health effects that have been associated with vitamin D deficiency raises the possibility that vitamin D levels may be a marker of poor health status rather than a cause of it. We investigated an association between vitamin D level and health-functional status.
  
  
  METHODS
  This cross-sectional study comprised 205 individuals who had taken a first plasma vitamin D test and were not symptomatic for vitamin D deficiency. During an interview, participants responded to questions regarding demographic information and their exposure to the sun, as well as a health-functional status questionnaire - World Organization of Family Doctors/COOP charts. Correlations between study variables and vitamin D levels were calculated. A stepwise linear regression was performed to estimate variables that independently predict vitamin D levels.
  
  
  RESULTS
  The participants were 51 men and 154 women, mean age 41 years. Vitamin D level was positively correlated with weekend sun exposure and negatively correlated with body mass index (BMI). A reported positive change in health over the previous 2 weeks correlated with a higher vitamin D level. Individuals with higher vitamin D levels were more likely to report participation in physical activity and to report capability of performing daily activities. A total of 176 (86%) of the study population was deficient in vitamin D, according to a level <30 ng mL-1. Vitamin D deficiency was associated with older age, higher BMI, Arab compared with Jewish ethnicity (darker skin), and religious identification (more body covering). In the multivariate analysis older age, female gender, religious identification, Arab ethnicity, higher BMI, sunscreen use and low exposure to sun during the weekdays all associated with lower vitamin D levels.
  
  
  CONCLUSIONS
  No parameter of functional health demonstrated capability of distinguishing vitamin D deficiency among healthy young to middle-aged adults.
authors.affiliation: Department of Family Practice, Leumit Health Services, Tel Aviv, Israel.
authors.forename: Avivit
authors.initials: A
authors.lastname: Golan-Cohen
authors.affiliation: Department of Family Practice, Leumit Health Services, Tel Aviv, Israel.
authors.forename: Eugene
authors.initials: E
authors.lastname: Merzon
authors.affiliation: Department of Family Practice, Leumit Health Services, Tel Aviv, Israel.
authors.forename: Ouda
authors.initials: O
authors.lastname: Alhin
authors.affiliation: Department of Family Medicine, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Eliezer
authors.initials: E
authors.lastname: Kitai
authors.affiliation: The Ruth & Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel.
authors.forename: Yacov
authors.initials: Y
authors.lastname: Fogelman
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D036301:Qualitative Research; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency
chemical_list: D014807:Vitamin D
keywords: health functional status; vitamin D deficiency; vitamin D screening