The effect of calcium and vitamin D supplements on blood pressure in postmenopausal women: myth or reality?

Hypertension is a highly prevalent disease with serious cardiovascular and renal complications. Many studies have demonstrated a weak correlation between the consumption of calcium (or calcium plus vitamin D) and blood pressure, suggesting that calcium supplements might reduce blood pressure. However, the results to date remain controversial. In this study, we assessed the effect of calcium and vitamin D supplementation on the blood pressure of postmenopausal women with hypertension as a population group in which the use of calcium supplements is prevalent. This triple-blind randomized clinical trial enrolled 98 women of postmenopausal age with hypertension in 2019. The study period was 8 weeks with close follow-up. We used 24-h ambulatory blood pressure monitoring to record the initial and final blood pressure in all participants. The changes in both the mean systolic (p = 0.047) and diastolic blood pressure (p = 0.015) were suggestive of an increase in blood pressure after consuming calcium and vitamin D supplements. Among patients who had been using calcium channel blockers, calcium and vitamin D supplementation caused a notable increase compared to baseline systolic (p = 0.019) and diastolic blood pressures (p = 0.001). The present results differ from those of previous studies. This suggests that calcium supplementation for postmenopausal women with hypertension requires the close observation of blood pressure to prevent any further increase, especially in women who are being treated with calcium channel blockers (clinicaltrial.gov registration: NCT04618952).