title: Sex and seasonal variations of plasma retinol, alpha-tocopherol, and carotenoid concentrations in Japanese dietitians.
abstract: OBJECTIVE
  To clarify sex and seasonal variations of plasma antioxidant concentrations among middle-aged Japanese.
  
  
  METHODS
  We investigated sex and seasonal variations of plasma antioxidant concentrations, including retinol, alpha-tocopherol, and carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein and lycopene), in 55 middle-aged dietitians (46 women and 9 men) in Aichi Prefecture, Central Japan, who took no supplements from autumn 1996 to summer 1997. Reversed-phase high performance liquid chromatography was used to measure plasma antioxidant concentrations in overnight-fasting blood samples.
  
  
  RESULTS
  Plasma levels of alpha-tocopherol, alpha-/beta-carotene, b-cryptoxanthin and lutein were significantly influenced by sex, being significantly higher for women than men in each corresponding season; retinol and lycopene, however, showed no such difference. For women, winter values of alpha-tocopherol, alpha-/beta-carotene, lutein and lycopene were significantly lower than corresponding summer values, and had reached their annual lowest. Retinol failed to show any significant seasonal variation, whereas the winter value of beta-cryptoxanthin had reached its annual highest. For men, beta-cryptoxanthin exhibited significant seasonal changes and was also highest in winter. Winter values of alpha-tocopherol, alpha-/beta-carotene and lycopene were lower compared with other seasons, but not statistically significant, probably due to the small sample size.
  
  
  CONCLUSIONS
  The findings indicate that sex and seasonal variations of plasma antioxidant concentrations should be taken into account in nutritional epidemiologic studies.
authors.affiliation: Dept of Science Research, Jiangsu Cancer Hospital and Research Institute, Nanjing, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Xiang
authors.forename: Teruo
authors.initials: T
authors.lastname: Nagaya
authors.forename: Xin-En
authors.initials: XE
authors.lastname: Huang
authors.forename: Kiyonori
authors.initials: K
authors.lastname: Kuriki
authors.forename: Nahomi
authors.initials: N
authors.lastname: Imaeda
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tokudome
authors.forename: Juichi
authors.initials: J
authors.lastname: Sato
authors.forename: Nakako
authors.initials: N
authors.lastname: Fujiwara
authors.forename: Shinzo
authors.initials: S
authors.lastname: Maki
authors.forename: Shinkan
authors.initials: S
authors.lastname: Tokudome
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D002338:Carotenoids / Q000097:blood*; D002851:Chromatography, High Pressure Liquid; D015331:Cohort Studies; D004045:Dietary Services; D019587:Dietary Supplements; D004046:Dietetics / Q000706:statistics & numerical data*; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D005260:Female; D005522:Food Services; D006801:Humans; D007564:Japan; D008019:Life Style; D008297:Male; D008875:Middle Aged; D011336:Probability; D012621:Seasons; D012737:Sex Factors; D018709:Statistics, Nonparametric; D014801:Vitamin A / Q000097:blood*; D024502:alpha-Tocopherol / Q000097:blood*
chemical_list: D000975:Antioxidants; D014801:Vitamin A; D002338:Carotenoids; D024502:alpha-Tocopherol