title: Noninvasive assessment of dermal carotenoids as a biomarker of fruit and vegetable intake.
abstract: BACKGROUND
  Resonance Raman spectroscopy (RRS) has been suggested as a feasible method for noninvasive carotenoid measurement of human skin. However, before RRS measures of dermal carotenoids can be used as a biomarker, data on intra- and intersubject variability and validity are needed.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the reproducibility and validity of RRS measures of dermal total carotenoids and lycopene in humans.
  
  
  METHODS
  In study 1, 74 men and women with diverse skin pigmentation were recruited. RRS measures of the palm, inner arm, and outer arm were obtained at baseline, 1 wk, 2 wk, 1 mo, 3 mo, and 6 mo (to maximize seasonal variation). The RRS device used visible light at 488 nm to estimate total carotenoids and at 514 nm to estimate lycopene. Reproducibility was assessed by intraclass correlation coefficients (ICCs). In study 2, we recruited 28 subjects and assessed dietary carotenoid intake, obtained blood for HPLC analyses, performed RRS measures of dermal carotenoid status, and performed dermal biopsies (3-mm punch biopsy) with dermal carotenoids assessed by HPLC.
  
  
  RESULTS
  ICCs for total carotenoids across time were 0.97 (palm), 0.95 (inner arm), and 0.93 (outer arm). Total dermal carotenoids assessed by RRS were significantly correlated with total dermal carotenoids assessed by HPLC of dermal biopsies (r = 0.66, P = 0.0001). Similarly, lycopene assessed by RRS was significantly correlated with lycopene assessed by HPLC of dermal biopsies (r = 0.74, P < 0.0001).
  
  
  CONCLUSIONS
  RRS is a feasible and valid method for noninvasively assessing dermal carotenoids as a biomarker for studies of nutrition and health.
authors.affiliation: Yale University Schools of Public Health and Medicine, New Haven, CT 06520-8034, USA. susan.mayne@yale.edu
authors.forename: Susan T
authors.initials: ST
authors.lastname: Mayne
authors.forename: Brenda
authors.initials: B
authors.lastname: Cartmel
authors.forename: Stephanie
authors.initials: S
authors.lastname: Scarmo
authors.forename: Haiqun
authors.initials: H
authors.lastname: Lin
authors.forename: David J
authors.initials: DJ
authors.lastname: Leffell
authors.forename: Erin
authors.initials: E
authors.lastname: Welch
authors.forename: Igor
authors.initials: I
authors.lastname: Ermakov
authors.forename: Prakash
authors.initials: P
authors.lastname: Bhosale
authors.forename: Paul S
authors.initials: PS
authors.lastname: Bernstein
authors.forename: Werner
authors.initials: W
authors.lastname: Gellermann
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D002338:Carotenoids / Q000032:analysis* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004032:Diet / Q000592:standards*; D005260:Female; D005638:Fruit; D006801:Humans; D000077276:Lycopene; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D015203:Reproducibility of Results; D012621:Seasons; D012867:Skin / Q000378:metabolism*; D012880:Skin Pigmentation; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014675:Vegetables; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002338:Carotenoids; D000077276:Lycopene