Prepared Foods May 16, 2005 enewsletter

According to a study from Japan, "Dolomite, a mineral composed of calcium magnesium carbonate, is used as a food supplement that supplies calcium and magnesium. However, the effect of magnesium supplementation on bone metabolism in patients with osteoporosis is a matter of controversy."

T. Mizoguchi and colleagues, Matsumoto Dental University, "examined the effects of daily supplementation with dolomite on calcium metabolism in ovariectomized (OVX) rats."

According to their study, "Dolomite was administered daily to OVX rats for nine weeks. The same amount of magnesium chloride as that supplied by the dolomite was given to OVX rats as a positive control."

"Histological examination revealed that ovariectomy decreased trabecular bone and increased adipose tissues in the femoral metaphysis. Dolomite or magnesium supplementation failed to improve these bone histological features," the researchers reported.

"Calcium content in the femora was decreased in OVX rats. Neither calcium nor magnesium content in the femora in OVX rats was significantly increased by dolomite or magnesium administration.

Urinary deoxypyridinoline excretion was significantly increased in OVX rats and was not affected by the magnesium supplementation. Serum concentrations of magnesium were increased, and those of calcium were decreased, in OVX rats supplemented with dolomite or magnesium. However, there was a tendency toward decreased parathyroid hormone secretion and increased calcitonin secretion in OVX rats supplemented with dolomite or magnesium. Serum 1.25-dihydroxyvitamin D-3 and osteocalcin levels were significantly increased in the supplemented OVX rats," Mizoguchi's group observed.

They said, "These results suggest that increased magnesium intake improves calcium metabolism in favor of increasing bone formation, through the modulation of calcium-regulating hormone secretion."

Mizoguchi and coauthors published the results of their research in the Journal of Bone and Mineral Metabolism (“Dolomite supplementation improves bone metabolism through modulation of calcium-regulating hormone secretion in ovariectomized rats.” J Bone Miner Metab, 2005;23(2):140-146).

For additional information, contact M. Ito, Matsumoto Dent. University, Institute Oral Science, Division Hard Tissue Research, 1780 Gobara, Hiro, Shiojiri 3990781, Japan.