A Dietary Comparison of High Phosphate Foods on Bone Health

Objectives: A chronic processed food diet can elevate serum inorganic phosphate (Pi) levels, leading to health risks such as cardiovascular complications, skeletal muscle dysfunction, and kidney disease. However, the effects of Pi on bone health have not been fully investigated. Thus, this study aimed to examine how solid and liquid high-phosphate type diets alter bone mineral density in oral and orthopedic bones.
Methods: Following IACUC approval, 36 male C57BL/6 mice were obtained for the normal phosphate (NP) and high-phosphate (HP) chow diet groups (CNP and CHP, 20 weeks old, n=10 per group), and the NP and HP liquid diet groups (LNP and LHP, 22 weeks old, n=8 per group). The diets included 0.9% total Pi for the NP group and 2.3% total Pi for the HP group during a 14-week period. A hemi-mandible and femur were dissected from each mouse and scanned using micro-computed tomography (micro-CT) at 10 and 20-micron voxel sizes. Bone voxels of the mandible and femur were segmented from non-bone voxels. The CT attenuation value of each bone voxel was calibrated to tissue mineral density (TMD). The mean and the lower and upper 5^th percentiles (Low₅ and High₅) of TMD were obtained based on a frequency plot of TMD. The TMD parameters were compared between the groups using a t-test.
Results: The CHP diet group had significantly lower values of all TMD parameters in the femur, as well as TMD Mean and High₅ in the mandible than the CNP group (p<0.04). However, there were no significant differences in any TMD parameters between the LNP and LHP diet groups (p>0.06).
Conclusions: These results suggest high Pi liquid diets may have a lesser effect on bone health compared to the solid food diet. Future studies will determine how Pi bioavailability impacts bone health.