A meta-analysis of 40 trials (2,492 subjects with high blood pressure) showed significant reductions in systolic blood pressure (SBP) of 1.8 mmHg and in diastolic blood pressure (DBP) of 0.99 mmHg associated with calcium supplementation (average dose: 1,200 mg/day). Among patients who had a calcium intake of 800 mg/day or less BP reductions were greater (SBP: -2.63 mmHg, DBP: -1.30 mmHg). (21)
In a review by Chung M et al, trials including hypertensive adults showed that calcium supplementation lowered systolic, but not diastolic, blood pressure by 2-4 mm Hg. (14)
Hypertension and osteoporosis link:
Hypertension and osteoporosis often co-exist. One of the only blood pressure medicines known to improve bone mineral density is hydrochlorothiazide (29). Hypertension and osteoporosis are often found together and how they are associated with calcium and/or vitamin D deficiency is yet to be explained.