QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (Publish Ahead of Print[PDF]) All Versions of this Article: 139/7/1308    most recent jn.108.101071v1 Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Shahnazari, M. Articles by Weaver, C. M. Search for Related Content PubMed PubMed Citation Articles by Shahnazari, M. Articles by Weaver, C. M.

---

Nutrient Physiology, Metabolism, and Nutrient-Nutrient Interactions

Diet Calcium Level but Not Calcium Supplement Particle Size Affects Bone Density and Mechanical Properties in Ovariectomized Rats^1,2

³ Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907 ⁴ School of Health and Human Performance, Dalhousie University, Halifax B3H 3J5, NS, Canada

Calcium (Ca) supplements, especially Ca carbonate (CaCO₃), are the main alternative sources of dietary Ca and an important part of a treatment regimen for osteoporosis, the most common metabolic bone disorder of aging and menopause. In a female ovariectomized (OVX) rat model for studying postmenopausal osteoporosis, we tested the hypothesis that a small compared with a large particle size of CaCO₃ (13.0- vs. 18.5-µm geometric diameter) would result in increased Ca balance and subsequently bone mass and that this would be affected by dietary Ca level. We used 6-mo-old rats that were OVX either at 6 or 3 mo of age as models of early or stable menopausal status, respectively. The rats received semipurified diets that contained either 0.4 or 0.2% dietary Ca provided from CaCO₃ of 2 particle sizes. A group of Sham-operated rats with intact ovaries served as control and were fed 0.4% dietary Ca from large particles. Estrogen deficiency as a result of ovariectomy had an adverse effect on bone density, mineral content, and bone mechanical properties (P < 0.001). Reducing dietary Ca from 0.4 to 0.2% resulted in significant adverse effects on bone density and mechanical properties (P < 0.001). The particle size of CaCO₃ did not affect total Ca balance, bone dual energy X-ray absorptiometry and peripheral quantitative computed tomography indices, bone ash and Ca content, or the mechanical determinants of bone strength. We conclude that a decrease in particle size of CaCO₃ to 70% of that typically found in Ca supplements does not provide a benefit to overall Ca metabolism or bone characteristics and that the amount of Ca consumed is of greater influence in enhancing Ca nutrition and skeletal strength.

^* To whom correspondence should be addressed. E-mail: weavercm{at}purdue.edu.

Manuscript received 20 October 2008. Initial review completed 14 November 2008. Revision accepted 13 May 2009.