One study has shown that taking calcium can interfere with the absorption of phosphorus, which, like calcium, is important for bone health. Although most western diets contain ample or even excessive amounts of phosphorus, older people who supplement with large amounts of calcium may be at risk of developing phosphorus deficiency. For this reason, the authors of this study recommend that, for elderly people, at least some of the supplemental calcium be taken in the form of tricalcium phosphate or some other phosphorus-containing preparation.
- Heaney RP, Nordin BEC. Calcium effects on phosphorus absorption: implications for the prevention and co-therapy of osteoporosis.J Am Coll Nutr 2002;21:239-44.