Vitamin D intake, Outdoor Activity Time and Serum 25-OH Vitamin D Concentrations of Korean Postmenopausal Women by Season and by Age / 대한지역사회영양학회지

ABSTRACT

OBJECTIVES: The purpose of this study was to examine the relative impact of seasonal differences and age on dietary vitamin D intakes, outdoor activity time and serum vitamin D status among Korean postmenopausal women. METHODS: A cross-sectional study was conducted with 164 free-living postmenopausal women (mean age=55.4 years) in Daegu, Korea. Dietary intake, daily physical activity patterns and fasting blood samples were collected during summer and winter. We compared the results from 75 women during summer and 89 women during winter. Dietary intake of vitamin D was assessed by 24-hour recall method. Daily outdoor activity time was derived from physical activity diary. RESULTS: The average dietary intake of vitamin D of the participants was 3.7 microg during summer, 3.3 microg during winter, showing no significant difference between the two seasons. The average time spent on outdoor activities was not significantly different between summer (=35.1 +/- 75.0 min/d) and winter (=48.5 +/- 76.8 min/d). The average serum 25-(OH) vitamin D concentrations of participants was 17.5 +/- 7.5 ng/mL in the summer and 13.4 +/- 4.3 ng/mL in the winter, showing no significant differences by season. Dietary intake of vitamin D was not related to age. When total subjects were divided into two groups by age, the average serum 25-(OH) vitamin D concentration was significantly higher in older group (p=0.047) and time spent on outdoor activities was also (p=0.018) significantly higher in the older group. CONCLUSIONS: In order to improve the current vitamin D status of Korean postmenopausal women, nutrition education programs should focus more on adequate intake of vitamin D, while maintaining enough outdoor activities over the season.