title: Non-invasive assessment of β-carotene levels in the skin of Colombian adults.
abstract: BACKGROUND
  Carotenoid pigments have antioxidant properties beneficial for human health. Use of resonance Raman spectroscopy (RRS) as a reliable method for measuring carotenoid levels in tissues such as dermis has been suggested. However, data about the variability and reproducibility of this technique should be collected before it can be used.
  
  
  OBJECTIVE
  To assess reproducibility of RRS for detection of total β-carotene levels in the skin of Colombian adults.
  
  
  METHODS
  Forty-eight healthy men and 30 healthy women with various pigmentation levels were enrolled into the study. Measurements by RRS were performed in the palmar region and medial and lateral aspects of the arms. Odds ratio and 95% confidence intervals were calculated, adjusting for confounding factors: body mass index, waist circumference, percent body fat, age, race, smoking, and sex. Reproducibility of the technique was estimated using intraclass correlation coefficient (ICC).
  
  
  RESULTS
  Mean β-carotene levels were 29.9 ± 11.9 in men and 30.6 ± 8.6 in women (P=.787). No differences or significant associations were found of β-carotene levels with confounding factors assessed by sex. ICCs were 0.89 in the palmar region, 0.85 in the medial aspect of arm, and 0.82 in the external aspect of arm.
  
  
  CONCLUSIONS
  RRS spectroscopy is a reliable method for non-invasive measurement of β-carotene levels in skin, and may be used as an important biomarker of antioxidant status in nutritional and health studies in humans.
authors.affiliation: Escuela de Medicina y Ciencias de la Salud, Colegio Mayor Nuestra Señora del Rosario, Bogotá DE, Colombia. robin640@hotmail.com
authors.forename: Robinson
authors.initials: R
authors.lastname: Ramírez-Vélez
authors.forename: Katherine
authors.initials: K
authors.lastname: González-Ruiz
authors.forename: Sophya
authors.initials: S
authors.lastname: García
authors.forename: Carlos Alejandro
authors.initials: CA
authors.lastname: López-Alban
authors.forename: Natalia
authors.initials: N
authors.lastname: Escudero
authors.forename: Ricardo Antonio
authors.initials: RA
authors.lastname: Agredo-Zúñiga
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000886:Anthropometry; D015415:Biomarkers; D003105:Colombia; D015986:Confounding Factors, Epidemiologic; D003430:Cross-Sectional Studies; D005006:Ethnicity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D010084:Oxidation-Reduction; D015203:Reproducibility of Results; D012737:Sex Factors; D012867:Skin / Q000737:chemistry*; D012880:Skin Pigmentation; D012907:Smoking / Q000453:epidemiology; D013059:Spectrum Analysis, Raman; D055815:Young Adult; D019207:beta Carotene / Q000032:analysis*
chemical_list: D015415:Biomarkers; D019207:beta Carotene