Vitamin D Intake and Progression of Urinary Incontinence in Women

Objective To determine if vitamin D intake is associated with reduced progression of urgency urinary incontinence (UI) in women. Methods We used the Nurses’ Health Study (NHS) I and NHSII cohorts to evaluate the association of vitamin D intake with progression of urgency UI and mixed UI, from mild-moderate to severe symptoms, from 2004 to 2012 (NHS) and 2005-2013 (NHSII). Intake of vitamin D at study baseline was categorized and updated at the start of each 2-4 year follow-up period. Multivariable-adjusted relative risks (RRs) and 95% confidence intervals (95% CI) of progression to severe UI were estimated using Cox proportional hazard models. Results At baseline, of the 20,560 older women (age range 58-73 years) in NHS I with mild/moderate urgency or mixed UI, 21% reported oral vitamin D intake of at least 800 IU per day. Among 12,573 middle-aged women (age range 42-59) in NHS II with mild/moderate urgency or mixed UI, 17% reported oral vitamin D intake of at least 800 IU daily. From 2004 to 2012, 4853 incident cases of urgency/mixed UI progression were identified among older women. From 2005 to 2013, 1378 incident cases of urgency/mixed UI progression were identified among middle-aged women. After multivariable adjustment, no significant associations between vitamin D intake and incidence of urgency/mixed UI progression were observed in either cohort (RR = 1.10, 95% CI 0.99-1.23 in older women, RR = 0.88, 95% CI 0.71, 1.10 in middle-aged women). Conclusion Despite interest in vitamin D as a low-cost strategy to prevent or reduce UI, our findings indicate oral vitamin D may not reduce urgency/mixed UI progression.