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.