HDCN Article Review/Hyperlink

Allender FS, Cutler JA, Follmann D, Cappuccio LP, Prer J, Elliott P

Dietary calcium and blood pressure: A meta-analysis of randomized clinical trials

Ann Int Med (May) 124:825-831 1996

Objective: To determine the effect of dietary calcium supplementation on blood pressure.

Methods: A meta-analysis based on a manual and MEDLINE search of published reports and review of meeting abstracts.

Results: 26 randomized trials were found; 13 involved normotensives and 16 hypertensives (3 trials included both). Four trials were excluded because of inadequate data, multifactorial intervention, absence of an effect estimate, and faulty study design. 28 strata from 22 trials (1231 persons) were included in the final analysis. The effect of calcium supplementation (median dose 1 g/d) on blood pressure was -0.18 mm Hg for diastolic blood pressure and -0.89 mm Hg for systolic blood pressure. The change in systolic pressure was stastically significant. This effect was seen in hypertensive but not normotensive persons. The decrease in sytolic pressure was most marked in older hypertensive women.

Conclusions: Although there is a stastifcally significant reduction in systolic blood pressure with calcium supplements in hypertensives, the effect is of questionable clinical significance.

Comment: This is a well-done meta-analysis and the results are of interest, given the uncertain role of calcium intake on blood pressure. It is of note that only one study has shown a convincing calcium-induced decrease in systolic blood pressure (McCarron and Morris, 1985); diastolic blood pressure has not decreased in any of the reported trials. However, it should be noted that calcium supplementation has never been shown to have a deterimental effect on blood pressure and although there is concern that it could have other deleterious effects such as increased kidney stones in stone formers, this is unproven. It is of interest that the effect of calcium on systolic pressure appears to be greatest in older women, the population in whom calcium supplements are often prescribed to prevent or treat osteoporosis. (David J. Leehey, M.D., Loyola University at Chicago)