Abstract
Data are presented which support the theory that most cases of primary postmenopausal osteoporosis (PPMO) are not caused by calcium deficiency. The commonly applied therapy of continuous supplementation solely with large doses of calcium is unlikely, therefore, to be of help. It is furthermore suggested that magnesium deficiency has a significant role in PPMO: magnesium is involved in calcium metabolism and in the synthesis of vitamin D, and in maintaining bone integrity. The results of a clinical evaluation of a dietary programme involving magnesium supplementation are also presented.