Associations of diet, supplement use, and ultraviolet B radiation exposure with vitamin D status in Swedish women during winter.
BACKGROUND
Vitamin D is produced endogenously after sun exposure but can also be obtained from natural food sources, food fortification, and dietary supplements.


OBJECTIVE
We aimed to determine the vitamin D status of women (61-86 y old) living in central Sweden (latitude 60 degrees ) during winter and its relation with vitamin D intake and exposure to ultraviolet B radiation.


METHODS
In a cross-sectional study, we assessed the vitamin D status (serum 25-hydroxyvitamin D [25(OH)D]) of 116 women by using an enzyme immunoassay. The women completed questionnaires covering food habits, use of dietary supplements, and sun-related behavior.


RESULTS
In a multiple linear regression model, the main determinants of serum 25(OH)D concentrations (x +/- SD: 69 +/- 23 mmol/L) were dietary vitamin D (6.0 +/- 1.8 mug/d), travel to a sunny location during winter within the previous 6 mo (26%), and the use of dietary supplements (16%). There was no association between serum 25(OH)D status during the winter and age, time spent outdoors, the use of sunscreen, or skin type. Serum 25(OH)D concentrations increased by 25.5 nmol/L with 2-3 servings (130 g/wk) fatty fish/wk, by 6.2 nmol/L with the daily intake of 300 g vitamin D-fortified reduced-fat dairy products, by 11.0 nmol/L with regular use of vitamin D supplements, and by 14.5 nmol/L with a sun vacation during winter. Among nonsupplement users without a wintertime sun vacation, 2-3 servings fatty fish/wk increased serum vitamin D concentrations by 45%.


CONCLUSIONS
Fatty fish, vitamin D-fortified reduced-fat dairy products, regular supplement use, and taking a sun vacation are important predictors for serum concentrations of 25(OH)D during winter at a latitude of 60 degrees .
Burgaz
Ann
A
Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
Akesson
Agneta
A
Oster
Annette
A
Michaëlsson
Karl
K
Wolk
Alicja
A
D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D012621:Seasons; D013472:Sunlight; D013548:Sweden; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000097:blood
D014807:Vitamin D; C104450:25-hydroxyvitamin D