Calcium supplementation: effect on blood pressure and urinary mineral excretion in normotensive male lactoovovegetarians and omnivores.

After an initial 4-wk period, 36 healthy male subjects aged 19-28 y (14 lactoovovegetarians and 22 omnivores) were given a supplement to their usual diet of 27.9 mmol calcium/d for 5 wk. During this period 22 blood pressure measurements were taken and 30 24-h urine specimens and 15 24-h dietary records were obtained. Base-line blood pressures did not differ significantly between vegetarians and omnivores (118.3/59.3 and 119.5/60.7, respectively). At the end of the supplementation period there was a decrease in diastolic blood pressure of 1.4 mm Hg (p less than 0.10) and an unexpected increase in systolic blood pressure of 2.1 mm Hg (p less than 0.01) in the omnivores. Although not significant, the same trends were observed in the vegetarians. In both groups Ca and magnesium excretions increased significantly and phosphorus excretion decreased significantly. Blood pressure of normotensive subjects with high basal Ca intake may not be sensitive to Ca supplementation.