Acute effects of an inorganic phosphorus additive on mineral metabolism and cardiometabolic risk factors in healthy subjects.

CONTEXT Hyperphosphatemia and high levels of fibroblast growth factor 23 (FGF23) are risk factors for cardiovascular events in patients with chronic kidney diseases. However, the impact of an inorganic phosphorus additive in healthy people is largely unknown. OBJECTIVE To investigate the acute effect of excessive dietary phosphorus administered as sodium-dihydrogen phosphate on the postprandial levels of Pi and FGF23 and the response to food. DESIGN Double-blind placebo-controlled crossover study. SETTING General community. PARTICIPANTS Twenty-nine healthy males and females. INTERVENTION Administration of a single dose of either 700 mg phosphorus (NaH2PO4) or a sodium-adjusted placebo in combination with a test meal. MAIN OUTCOME MEASURE Postprandial plasma levels of Pi and FGF23. RESULTS Compared to placebo, oral phosphorus increased the plasma Pi level, which remained elevated during the ensuing 8 h (at 480 min: 1.31 vs. 1.16 mmol/l, P < 0.001), increased urinary Pi (iAUC0-480 789 vs. 95 mmol/mmol, P < 0.001), reduced tubular Pi reabsorption (iAUC0-480 -31.5 vs. -6.2, P < 0.001), decreased urinary calcium (iAUC0-240 30.6 vs. 53.0 mmol/mmol, P = 0.009), and stimulated the release of parathyroid hormone (iAUC0-480 2212 vs. 768 ng/l, P < 0.001). However, the FGF23 levels did not change. Postprandial levels of glucose, insulin, and lipids were not substantially affected by phosphorus vs. placebo. CONCLUSION An oral phosphorus load can induce elevated postprandial levels of circulating Pi for hours in healthy subjects, despite rapid homeostatic counterreactions. FGF23 levels and the postprandial response to food were not affected.