Don't forget the phosphorous for bone growth

Calcium and phosphorus are co-dependent in bone development and should be supplemented togther, suggests research in a recent journal.

Dr Ralph Shapiro of Product Safety Labs in New Jersey, US and Dr Robert P. Heaney of Creighton University Medical Center (Omaha, NE) set out to quantify the effect of variation in calcium intake, with and without supplemental phosphorous, on growth and bone development in growing animals under conditions of varying calcium and phosphorus deficiency.

Nine groups of weanling male rats were fed a diet without sufficient calcium and phosphorus for 28 days. The diet provided nine levels of varying calcium and phosphorus repletion, using either calcium carbonate, dicalcium phosphate, or tricalcium phosphate.

At the end of the study, the femurs from each animal were weighed, measured for tensile strength, bone mineral content (BMC), and bone density, and analysed for ash, calcium, phosphorus, and histology. As expected, at equivalent levels of calcium supplementation, the two phosphorus-containing salts promoted significantly greater improvement in all the bone variables measured, as well as greater body weight gain and diet and calcium use, compared to animals supplemented with calcium only, reported the researchers in the May issue of Bone​.

In analysis models, the value for the phosphorus coefficient was three to sixfold larger than that for the calcium term, indicating a substantially greater effect of varying phosphorus intake than of varying calcium, they added.