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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.

Plant proteins have become increasingly important for ecological reasons. Rapeseed is a novel source of plant proteins with high biological value, but its metabolic impact in humans is largely unknown. A randomized, controlled intervention study including 20 healthy subjects was conducted in a crossover design. All participants received a test meal without additional protein or with 28 g of rapeseed protein isolate or soy protein isolate (control). Venous blood samples were collected over a 360-min period to analyze metabolites; satiety was assessed using a visual analog scale. Postprandial levels of lipids, urea, and amino acids increased following the intake of both protein isolates. The postprandial insulin response was lower after consumption of the rapeseed protein than after intake of the soy protein (p < 0.05), whereas the postmeal responses of glucose, lipids, interleukin-6, minerals, and urea were comparable between the two protein isolates. Interestingly, the rapeseed protein exerted stronger effects on postprandial satiety than the soy protein (p < 0.05). The postmeal metabolism following rapeseed protein intake is comparable with that of soy protein. The favorable effect of rapeseed protein on postprandial insulin and satiety makes it a valuable plant protein for human nutrition.