Phosphorus-Based Food Additives May Impact Bone Metabolism
Even healthy adults show evidence of abnormal bone metabolism.
Orlando M. Gutierrez, MD, of the University of Alabama at Birmingham, and colleagues examined the impact of phosphorus-based food additives on markers of bone and mineral metabolism. Ten healthy participants consumed a low additive diet (about 1,000 mg phosphorus daily) for 1 week followed by an enhanced additive diet of identical food items containing phosphorus additives (1,677 mg phosphorus daily). The average difference in daily phosphorus between the diets was 606 mg. Calcium consumption was kept stable across diets.
The low additive diet represented U.S. Department of Agriculture recommendations on daily phosphorus intake. Actual dietary consumption of phosphorus in the United States far exceeds these recommendations. Phosphorus-based additives account for 10% to 50% of daily intake in a typical Western diet, according to background information.
Results published online in the Journal of Clinical Endocrinology and Metabolism showed the additive-enhanced diet significantly increased circulating fibroblast growth factor 23 (FGF-23), osteopontin, and osteocalcin concentrations by 23%, 10%, and 11%, respectively, and decreased sclerostin.
The investigators performed a parallel study in animals and found similar results: FGF-23, osteopontin and osteocalcin increased, whereas sclerostin decreased. The animals also had measurable reduction in bone mineral density.
Endocrine factors have been linked with both bone and cardiovascular disease. In bone health, they either affect bone metabolism or reflect changes in bone homeostasis. “These results suggest that changes in dietary phosphorus consumption can influence gene expression in different tissues even with normal renal function,” the investigators commented. “However, whether these changes are due to a direct effect or due to changes in systemic factors still need to be determined.”
Previous studies on phosphorus used phosphorus supplements rather than foods typically eaten. The new study excluded people with kidney disease, thyroid disease, obesity, and other medical factors believed to affect phosphorus levels.
Future studies with longer follow-up may help elucidate any physiological adaptations that may occur, they suggested. Sclerostin levels, for example, may have fallen as an adaptive response to preserve bone mass.