Abstract 1069: Does a Higher Serum 25(OH) Vitamin D Level Predict Lower Blood Pressure in Post-menopausal Women? Prospective Data From the Women’s Health Initiative
BACKGROUND Some animal and human studies suggest that vitamin D supplementation may lower blood pressure (BP), and a large prospective study found that the risk of incident hypertension (HTN) was inversely related to plasma levels of 25(OH) vitamin D. Accordingly, we studied the relation between baseline levels of 25(OH) vitamin D and changes in BP in postmenopausal women enrolled in the Women’s Health Initiative (WHI).
METHODS - Baseline serum vitamin D levels were measured in 4867 participants in 2 nested case-control studies in the WHI calcium/vitamin D trial. Vitamin D quartiles (<34.4, 34.4–47.6, 47.7–64.6 and ≥64.7 nmol/L) were created based on the levels in the combined control groups. Treatment for HTN was determined by self-report supplemented by periodic medication inventories, and HTN at baseline was defined as BP ≥140/90 or treatment with antihypertensive medication. BP was measured annually by trained technicians using a standard protocol. Change in BP was determined using linear repeated measures regression modeling, adjusting for potential confounders.
RESULTS At baseline, the mean age was 66±7 years, mean BP was 127/74 mm Hg, and 49% of the participants had hypertension. Over a median follow-up time of 7 years, there were no significant differences in the mean change over time in systolic BP (figure⇓) or diastolic BP by quartile of serum 25(OH) vitamin D. Similar results were seen in stratified analyses of women with and without HTN at baseline, and in women who were never or ever treated with antihypertensive medication.
CONCLUSIONS In postmenopausal women, there was no association of the level of 25(OH) vitamin D with change in BP over 7 years of follow-up.