Authors:
Kimlin MG, Lucas RM, Harrison SL, Van Der Mei I, Armstrong BK, Whiteman DC, Kricker A, Nowak M, Brodie AM, Sun J
Authors notes:
American Journal of Epidemiology 179(7): 864-874.
Keywords:
determinants, sunlight, ultraviolet, vitamin D, 25 hydroxyvitamin D, adult
Abstract:
The Quantitative Assessment of Solar UV [ultraviolet] Exposure for Vitamin D Synthesis in Australian Adults (AusD) Study aimed to better define the relationship between sun exposure and serum 25-hydroxyvitamin D (25(OH)D) concentration.
Cross-sectional data were collected between May 2009 and December 2010 from 1,002 participants aged 18-75 years in 4 Australian sites spanning 24° of latitude.
Participants completed the following: 1) questionnaires on sun exposure, dietary vitamin D intake, and vitamin D supplementation; 2) 10 days of personal ultraviolet radiation dosimetry; 3) a sun exposure and physical activity diary; and 4) clinical measurements and blood collection for 25(OH)D determination.
Our multiple regression model described 40% of the variance in 25(OH)D concentration; modifiable behavioral factors contributed 52% of the explained variance, and environmental and demographic or constitutional variables contributed 38% and 10%, respectively.
The amount of skin exposed was the single strongest contributor to the explained variance (27%), followed by location (20%), season (17%), personal ultraviolet radiation exposure (8%), vitamin D supplementation (7%), body mass index (weight (kg)/height (m) 2) (4%), and physical activity (4%). Modifiable behavioral factors strongly influence serum 25(OH)D concentrations in Australian adults.
In addition, latitude was a strong determinant of the relative contribution of different behavioral factors.