ABSTRACT
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, 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.
ABSTRACT
OBJECTIVE: Development of a data-based short food frequency questionnaire (FFQ) for evaluating intake of nutrients by middle-aged Japanese. METHODS: Of 102 foods listed in the formerly developed semi-quantitative FFQ, foods having similar nutrient contents were combined into 72 foods/food groups by research dietitians. Nutrient contents were computed by multiplying the weight of foods consumed and its nutrient contents. Next, a cumulative multiple regression coefficient up to 0.85 was applied, and 47 foods/food groups were chosen for a brief FFQ for assessing intake of 21 nutrients including energy, protein, fat, carbohydrate, vitamins, minerals, and dietary fibers. RESULTS: The 47 foods/food groups comprised rice, bread and noodles (3), margarine/butter (2), eggs (1), milk and dairy products (2), soybean and soybean products (3), miso-soup (1), meat including beef, pork and chicken (4), fish (3), other fish, shellfish and fish products (4), green-yellow vegetables (5), other vegetables and mushrooms (3), edible roots (4), seaweeds (1), mayonnaise (1), fried dishes (2), seeds (1), fruit (2), beverages, including alcohol (3), and confectioneries (2). CONCLUSIONS: The evidence-based short FFQ efficiently covered the intake of 21 nutrients, and may be competent to rank the middle-aged general public Japanese according to intake of nutrients.