Patients with chronic kidney disease (CKD) are unable to adequately expel phosphorus, a mineral that can accumulate to toxic levels in the body, but data from a recent study indicate that patients who ate a vegetarian diet absorbed less of the nutrient than those who ate meat.

“Dietary counseling for CKD patients is complex, and patients are frequently confused by the multitude of recommendations,” wrote Sharon Moe, MD, of the Indiana University School of Medicine and Roudebush Veterans’ Affairs Medical Center, both in Indianapolis, and colleagues.

Hoping to come up with a solution to simplify these dietary recommendations, the researchers compared phosphorous levels in the blood and urine of nine patients with CKD, who ate either vegetarian- or meat-based diets. The findings will be published in the Jan. 2011 issue of the Clinical Journal of the Society of Nephrology.

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Despite consuming vegetarian- and meat-based meals that contained equal amounts of protein and phosphorus concentrations, patients who ate vegetables only had lower blood phosphorus levels and decreased phosphorus excretion in their urine after one week.

In Western nations, most phosphorus is ingested from protein and dairy products as well as preservatives and additives, according to background information in the article.

Although the researchers did not investigate why patients on the vegetarian diet absorbed less phosphorus, they noted that grain-based diets have lower phosphate-to-protein ratios and that much of the phosphate in vegetables comes from phytate — a nutrient not absorbed in humans.

“Although we advise our CKD patients to follow a phosphate-restricted diet, we rarely discuss the protein source of phosphate, which we have now demonstrated to be important,” the researchers wrote.

These results still need to be confirmed in longer studies, according to the researchers. In the meantime asking patients to eat more grains, less meat and less packaged and prepared food, could simplify efforts to limit phosphorus intake while increasing the amount of protein these patients consume.