Effect of a plant protein-rich diet on postprandial phosphate metabolism in healthy adult men: a randomised controlled trial.

BACKGROUND: This study examined the effects of animal protein- and plant protein-rich diets on postprandial phosphorus metabolism in healthy male subjects.

METHODS: The study was conducted by randomised parallel-group comparison of healthy men aged 21-24 years. In Study 1, participants were divided into two groups and consumed either a 70% animal protein diet (AD, n = 6) or a 70% plant protein diet (PD, n = 6). In Study 2, participants were divided into three groups and consumed either AD (n = 10), PD (n = 10) or AD + DF, a 70% animal protein diet loaded with the same amount of fibre as PD (n = 9). The phosphorus contents of the diets used in this study were nearly equivalent (AD, 710.1 mg; PD, 709.7 mg; AD + DF, 708.9 mg). Blood and urine samples were collected before, and 2 and 4 h after the meal to measure phosphorus and calcium levels.

RESULTS: In Study 1, PD consumption resulted in lower blood and urinary phosphorus concentrations 2 h postprandially compared with AD (p < 0.05). In Study 2, blood phosphorus levels in AD + DF after the diet remained lower, but not significantly so compared with AD, and urinary phosphorus levels were significantly lower 2 h postprandially (p < 0.05).

CONCLUSIONS: A plant protein-rich diet reduced rapid postprandial increases in blood and urinary phosphorus concentrations compared with the animal protein-rich diets, suggesting that dietary fibre may play a partial role in the postprandial decreases in blood and urinary phosphorus concentrations.