(1) Post-menopausal women (age ≥50 years of age); (2)Urine leakage for 3 or more months; (3) at least 3 urinary urgency incontinence episodes on a 7-day bladder diary; and (4) serum 25(OH)D level (vitamin D) is <30 ng/mL. Women who currently take a bladder medications (anticholinergic) for UI symptom control may enroll into the study if they agree to (1) cease taking these medications at least two weeks before the pre-intervention assessment and (2) not take these medications during the study's treatment and assessment period.