Sex and Seasonal Variations of Plasma Retinol, a-Tocopherol, and Carotenoid Concentrations in Japanese Dietitians

Aim: To clarify sex and seasonal variations of plasma antioxidant concentrations among middle-aged Japanese.Subjects and
Methods: We investigated sex and seasonal variations of plasma antioxidant concentrations,including retinol, α-tocopherol, and carotenoids (α-carotene, β-carotene,β-cryptoxanthin, lutein and lycopene),in 55 middle-aged dietitians (46 women and 9 men) in Aichi Prefecture, Central Japan, who took no supplementsfrom autumn 1996 to summer 1997. Reversed-phase high performance liquid chromatography was used tomeasure plasma antioxidant concentrations in overnight-fasting blood samples.
Results: Plasma levels of α-tocopherol, α-/β-carotene, β-cryptoxanthin and lutein were significantly influenced by sex, being significantlyhigher for women than men in each corresponding season; retinol and lycopene, however, showed no suchdifference. For women, winter values of α-tocopherol, α-/β-carotene, lutein and lycopene were significantlylower than corresponding summer values, and had reached their annual lowest. Retinol failed to show anysignificant seasonal variation, whereas the winter value of β-cryptoxanthin had reached its annual highest. Formen, β-cryptoxanthin exhibited significant seasonal changes and was also highest in winter. Winter values of α-tocopherol, α-/β-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 ofplasma antioxidant concentrations should be taken into account in nutritional epidemiologic studies.