Author(s): Kluczynski MA, Lamonte MJ, Mares JA, Wactawski-Wende J, Smith AW, Engelman CD, Andrews CA, Snetselaar LG, Sarto GE, Millen AE. Duration of physical activity and serum 25-hydroxyvitamin D status of postmenopausal women. Ann Epidemiol. 2011 Jun;21(6):440-9. doi: 10.1016/j.annepidem.2010.11.011. Epub 2011 Mar 17. PMID 21414803
Journal: Annals Of Epidemiology, Volume 21, Issue 6, Jun 2011
PURPOSE To investigate whether the association between physical activity and serum 25-hydroxyvitamin D (25(OH)D) concentrations is independent of sun exposure, body size, and other potential explanatory variables.
METHODS By using data from a sample of 1343 postmenopausal women from the Women’s Health Initiative, we used linear regression to examine the associations of duration (minutes/week) of recreational activity and of yard work with 25(OH)D concentrations (nmol/L).
RESULTS In age-adjusted analyses, positive associations were observed between 25(OH)D concentrations and both duration of recreational physical activity (β = 0.71, SE [0.09], p <.001) and yard work (β = 0.36, SE [0.10], p = .004). After further adjustment for vitamin D intake, self-reported sunlight exposure, waist circumference, and season of blood draw, 25(OH)D was significantly associated with recreational activity (β = 0.21, SE [0.09], p = .014) but not with yard work (β = 0.18, SE [0.09], p = .061). Interactions were observed between season and both recreational activity (P(interaction) = .082) and yard work (P(interaction) = .038) such that these activity-25(OH)D associations were greater during summer/fall compared with winter/spring. Self-reported sunlight exposure and measures of body size did not modify the associations.
CONCLUSIONS The observed age-adjusted activity-25(OH)D associations were attenuated after adjusting for explanatory variables and were modified by season of blood draw. Adopting a lifestyle that incorporates outdoor physical activity during summer/fall, consuming recommended amounts of vitamin D, and maintaining a healthy weight may improve or maintain vitamin D status in postmenopausal women.