As kidney disease progresses, there is a rise in parathyroid hormone (PTH) and fibroblast growth factor- 23 (FGF23) to increase urinary phosphate excretion and maintain normal serum phosphate levels until late in the course of kidney disease. At that time, this compensation is inadequate and hyperphosphatemia develops, and this is associated with arterial calcification and mortality in patients with kidney disease. In addition, chronic and persistent elevation in PTH and FGF23 can lead to adverse consequences such as left ventricular hypertrophy and bone loss. Thus, intervening by decreasing intestinal phosphorus absorption may prevent the rise in phosphate, PTH, and FGF23 levels that are observed with progressive kidney disease, leading to beneficial effects over time. One approach to decreasing intestinal phosphorus absorption is to ingest foods with lower bioavailable phosphorus. Grain-based (vegetarian) sources of protein contain phosphorus bound to phytate. Humans lack the enzyme phytase, and thus hydrolysis of phytate to release phosphate is reduced. In a rat model of chronic kidney disease (CKD), a grain-based versus synthetic casein-based protein diet of equivalent total phosphate and protein content led to reduced urinary phosphate excretion, lower PTH and FGF23 levels, and slower progression of kidney disease. In humans with stage 3b to 4 chronic kidney disease, a small cross-over trial found reduced urinary phosphate excretion with 100% vegetarian versus 100% meat-based diet consumed for one week. In a four-week study, a 70% plant-based diet similarly decreased the urinary phosphate excretion in patients with advanced kidney disease. Thus, grain/vegetarian-based diets contain less bioavailable phosphate and can provide an adequate source of protein yet decrease intestinal phosphate absorption. Long-term studies are needed to fully assess safety and efficacy.
|Original language||English (US)|
|Title of host publication||Dietary Phosphorus|
|Subtitle of host publication||Health, Nutrition, and Regulatory Aspects|
|Number of pages||12|
|State||Published - Jan 1 2017|
ASJC Scopus subject areas