title: Hair dyeing, hair washing and hair cortisol concentrations among women from the healthy start study.
abstract: Hair cortisol concentration (HCC) has been suggested as a promising marker for chronic stress. However, studies investigating the influence of hair dyeing and hair washing frequency on HCC have shown inconsistent results.
  
  
  
  To examine associations between HCC and hair dyeing status or weekly hair washing frequency among women.
  
  
  
  This cross-sectional study was based on data from 266 mothers participating in the Healthy Start intervention study. HCC was measured in the proximal end of the hair (1-2cm closest to the scalp) while hair dyeing status, frequency of hair washing and covariates were reported by the women. Linear regression analyses were applied to assess the associations between HCC and hair dyeing or weekly frequency of hair washing.
  
  
  
  No statistically significant difference (p=0.91) in HCC was found between women who dyed hair (adjusted mean: 137pg/mg [95% CI: 122,153]) and women with natural hair color (adjusted mean: 139pg/mg [95% CI: 123,155]). Frequency of hair washing was not associated with HCC (β: -3.7 [95% CI: -9.0, 1.5; P=0.20]).
  
  
  
  This study of 266 Danish women provides no evidence in support of an association between HCC and hair dyeing status or hair washing frequency.
authors.affiliation: Research Unit for Dietary Studies at The Parker Institute, The Capital Region, Copenhagen, Denmark.
authors.forename: Sheila K
authors.initials: SK
authors.lastname: Kristensen
authors.affiliation: Research Unit for Dietary Studies at The Parker Institute, The Capital Region, Copenhagen, Denmark. Electronic address: sofus.larsen@regionh.dk.
authors.forename: Sofus C
authors.initials: SC
authors.lastname: Larsen
authors.affiliation: Research Unit for Dietary Studies at The Parker Institute, The Capital Region, Copenhagen, Denmark.
authors.forename: Nanna J
authors.initials: NJ
authors.lastname: Olsen
authors.affiliation: Department of Clinical Biochemistry, Faculty of Health Sciences, Bispebjerg Hospital, DK-2400 Copenhagen NV, Denmark.
authors.forename: Jan
authors.initials: J
authors.lastname: Fahrenkrug
authors.affiliation: Research Unit for Dietary Studies at The Parker Institute, The Capital Region, Copenhagen, Denmark; The National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark; The Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, The University of Sydney, Sydney, Australia; Department of Public Health, Section for General Practice, University of Copenhagen, Denmark.
authors.forename: Berit L
authors.initials: BL
authors.lastname: Heitmann
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis; D003430:Cross-Sectional Studies; D005260:Female; D006197:Hair / Q000737:chemistry*; D006202:Hair Dyes; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D006920:Hygiene; D013315:Stress, Psychological / Q000175:diagnosis* / Q000503:physiopathology; D055815:Young Adult
chemical_list: D015415:Biomarkers; D006202:Hair Dyes; D006854:Hydrocortisone
keywords: Chemicals; Chronic stress; Hair cortisol; Hair dye; Hair wash; Shampoo