Perspective: Plant-based Whole-Grain Foods for Chronic Kidney Disease: The Phytate-Phosphorus Conundrum

Restriction of dietary phosphorus intake is an important component of good clinical practice in kidney failure patients, particularly after dialysis initiation. Greater consumption of predominantly plant-based diets, including phytate-rich foods, is increasingly recommended for health maintenance/disease prevention in this population, with the implicit assumption that phytate-phosphorus in whole-grain cereals, legumes, pulses, and nuts is poorly absorbed. Review of human interventions with diets high in phytate-phosphorus indeed suggests an absorption of at least 50%, still less than animal protein-bound phosphorus, but higher than the generally believed 10-30%. Factors largely ignored up to now, but of potential influence on phytate-phosphorus bioavailability, include effect of food processing in releasing phosphorus, action of colonic bacteria that are able to release inorganic phosphorus, and capacity of the colon to absorb phosphorus. These issues may become increasingly important as new plant-based alternatives to meats, all containing phytate, are being rapidly introduced in the market.