BIOAVAILABILITY OF CALCIUM AND MAGNESIUM FROM MAGNESIUM CITRATE CALCIUM MALATE - IMPLICATIONS FOR OSTEOPOROSIS PREVENTION

objectives To assess the bio-availability of calcium and magnesium fro m an organic complex (magnesium citrate calcium malate (MCCM)) and to characterise MCCM supplementation with regard to the parathyroid hormo ne (PTH) response, acid-base homeostasis and selective parameters of b one resorption and formation. Design. Controlled trial where oral MCCM and water were compared. Administration of citrate and malate with po tassium and sodium as counter cations served as control treatment. Sub jects. Sixteen apparently healthy women. Setting. Institute of Patholo gy, University of Pretoria. Outcome measures. Plasma ionised calcium, serum intact PTH, serum osteocalcin, urine calcium, magnesium and deox ypyridinoline and blood bicarbonate, as well as blood and urine pH, we re monitored in the study. Results. Compared with water, a single oral dose of 5 g MCCM (containing 500 mg calcium and 250 mg magnesium) res ulted in significant increases in plasma ionised calcium (3.1%; P < 0. 01), urine calcium (213.6%; P < 0.001), urine magnesium (212.6%; P < 0 .001) and blood standard bicarbonate (3.8%; P < 0.05) concentrations, while serum intact PTH concentrations decreased (-31.6%; P < 0.001). C itrate and malate per se had no calciuric effect. Following 12-13 days of MCCM treatment, the mean (SD) urinary deoxypyridinoline excretion declined from 8.01 (3.02) to 6.95 (2.39) nmol/mmol creatinine (P = 0.0 12). Conclusions. MCCM is a suitable compound for both calcium and mag nesium delivery. Treatment with MCCM may result in reduced bone resorp tion, as indicated by lower intact serum PTH concentrations and less u rinary deoxypyridinoline excretion.