title: Skin pigmentation, sun exposure and vitamin D levels in children of the Avon Longitudinal Study of Parents and Children.
abstract: BACKGROUND
  It has been hypothesised that light skin pigmentation has arisen to ensure adequate levels of vitamin D as human populations moved out of Africa and into higher latitudes. Vitamin D, which is primarily obtained through exposure to sunlight (specifically ultraviolet radiation B (UVR-B)), has been inversely associated with several complex diseases. Greater sun exposure, on the other hand, is a well-known cause of skin cancer. The potential of UVR to be beneficial for some health outcomes but detrimental for others has prompted a public health debate on how to balance the positive and negative consequences of sun exposure. In this study we aimed to determine the validity of the evolutionary hypothesis linking lighter skin with higher vitamin D concentrations in a European population. Additionally, we aimed to examine the influence of pigmentation on personal behaviour towards sunlight exposure and the effects of this behaviour on vitamin D.
  
  
  METHODS
  We combined genetic variants strongly associated with skin colour, tanning or freckling to create genetic scores for each of these phenotypes. We examined the association of the scores with pigmentary traits, sun exposure and serum 25-hydroxyvitamin D (25(OH)D) levels among children of the Avon Longitudinal Study of Parents and Children (ALSPAC, N = 661 to 5649).
  
  
  RESULTS
  We found that fairer-skinned children, i.e. those with higher pigmentation score values, had higher levels of 25(OH)D (0.6 nmol/l; 95% CI 0.2, 1.0; per unit increase in skin colour score; N = 5649). These children also used more protection against the damaging effects of UVR.
  
  
  CONCLUSIONS
  In this population taking protective measures against sunburn and skin cancer does not seem to remove the positive effect that having a less pigmented skin has on vitamin D production. Our findings require further replication as skin pigmentation showed only a small effect on circulating 25(OH)D.
authors.affiliation: School of Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK. C.Bonilla@bristol.ac.uk.
authors.forename: Carolina
authors.initials: C
authors.lastname: Bonilla
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Ness
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Wills
authors.forename: Debbie A
authors.initials: DA
authors.lastname: Lawlor
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Lewis
authors.forename: George
authors.initials: G
authors.lastname: Davey Smith
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D010290:Parents; D010641:Phenotype; D012878:Skin Neoplasms / Q000209:etiology / Q000517:prevention & control*; D012880:Skin Pigmentation / Q000235:genetics / Q000502:physiology*; D013472:Sunlight / Q000009:adverse effects; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*; D044465:White People
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D