Bioavailability of calcium from four different sources

Abstract

Bone mineralization and mineral retention were measured to evaluate calcium (Ca) bioavailability from four different sources at two dietary levels (40% or 100% of NRC requirement). The bioavailability of Ca from Ca carbonate, Ca citrate, tricalcium phosphate, and reduced particle size Ca citrate was determined in Sprague Dawley rats. Femur, feces and urine levels of phosphorus and magnesium were also determined. Animals (9/group) were fed semisynthetic diets containing 0.2% or 0.5% Ca from each source for seven weeks. A three-day Ca balance was determined during weeks four and seven. There was no significant effect of Ca source on percent Ca retained or femur Ca concentrations at either level of Ca tested. Animals fed the 0.2% Ca diets retained a larger percent of ingested Ca and had lower bone calcium levels than those fed 0.5% Ca Diets. When Ca intake was low, the source of Ca appears to influence bone strength and stiffness. These results indicate that, in the rat, there is no significant difference in Ca biovailability from the four sources tested.