Vegetarian diet cuts toxic phosphorus levels

Eating a vegetarian diet lowers kidney disease patients' levels of potentially toxic phosphorus in the blood and urine.

Kidney disease patients have to limit their intake of phosphorous - which is found in dietary proteins and is a common food additive - because their bodies have difficulty ridding themselves of the mineral. In these patients, high levels of phosphorus can lead to heart disease and death.

Researchers examined the effects of vegetarian and meat-based diets on phosphorous levels in nine patients in America with chronic kidney disease (CKD). Each patient ate a vegetarian or meat-based diet for one week and then waited two to four weeks before eating the other diet for a week. They conducted blood and urine tests at the end of each week on both diets. Even though the two diets had equivalent protein and phosphorus concentrations, it was found that patients had lower blood and urine phosphorus levels after they ate the vegetarian diet.

The investigators didn't examine the reasons for this difference, but they noted that a grain-based diet has a lower phosphate-to-protein ratio and much of the phosphate is in the form of phytate, which is not absorbed in humans.

The findings show that the source of protein in a diet has a major effect on phosphorous levels in chronic kidney disease patients. Therefore, dietary counseling of patients with CKD must include information on not only the amount of phosphate but also the source of protein from which the phosphate derives.

The above results, if confirmed in larger studies, provide rationale for recommending a predominance of grain-based vegetarian sources of protein to patients with CKD. This diet would allow increased protein intake without adversely affecting phosphorus levels.