Bone-Sparing by Ca Salts With & Without Extra Phosphorus

Creighton University, Omaha NE

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Abstract

Bone mineral is basically calcium phosphate, and both elements (Ca and P) are required for bone acquisition. Typical Ca intakes in the U.S. are lower than current recommendations, and typical P intakes, higher. Thus attention has been focused mainly on increasing Ca intake, by supplementation and food fortification. The salt most commonly used for these purposes is calcium carbonate. But while the average P intake tends to be adequate or generous, nevertheless substantial proportions of older women ingest less than 70% of the RDA for phosphorus on any given day, and hence may be said to be at risk for P deficiency. When these women are given a combination of anabolic therapy and supplemental Ca (as the carbonate), the added Ca may uncover and aggravate the latent P deficiency. This is both because Ca binds phosphate in the gut and reduces its absorption (thereby effectively lowering the P intake still further) and because the induced bone anabolism will itself consume phosphorus, as a result of which absorbed phosphorus may not be sufficient to support the increase in bone mineral mass made possible by this therapy. To test the possible importance and value of supplementing both of the components of bone mineral in support of anabolic therapy of osteoporosis, we propose a 1-year randomized trial, comparing, in two groups of teriparatide-treated postmenopausal osteoporotic women, calcium supplements with and without extra phosphorus (i.e., Ca phosphate vs. Ca carbonate). The principal outcome measure will be change in bone mineral content over the one year of the trial. A secondary outcome is measurement of bone resorption biomarkers so as to assess whether the phosphate salt elevates remodeling relative to the carbonate salt. A finding of superiority of the phosphate-containing cost-neutral change in Ca sources and a corresponding osteoporosis prophylaxis as well). PERFORMANCESITE(S) _an_a_n, ci_,s_ Creighton University Medical Center Osteoporosis Research Center 601N. 30th Street Omaha, NE 68131 KEY PERSONNEL. See instructions. Use continuation pages as needed Start with Pdncipal Investigator. List all other key personnel in alphabetical Name O_anization to provide the required order, last name first. Robert P. Heaney, M.D. Creighton University Robert R. Recker, M.D. Creighton University Creighton University Ca supplement would provide evidence leading to a improvement in osteoporosis co-therapy (and possibly information in the format shown below. RoleonP_e_ Principal Investigator Co-investigator Co-investigator Joan M. Lappe, Ph.D. Disclosure Permission Statement. Applicable to SBIPJSTTR Only, See instructions. [] Yes [] No PHS 398 (Rev. 05/01 ) Page _2 Form Page 2 Principal Investigator/Program Director (Last, first, middle): Heaney, Robert P. The name of the principal investigator/program director must be provided at the top of each printed page and each continuation page, RESEARCH GRANT TABLE OF CONTENTS Page Numbers Face Page .................................................................................................................................................. 1 Description,