Veggie Diet Best for Kidney Patients

A grain-based vegetarian diet may be better than a meat-based diet in terms of holding down phosphorus levels in patients with CKD….

Sharon Moe, MD, of Indiana University in Indianapolis, and colleagues reported that, “Even though they ingested the same amount of phosphorus, patients on the vegetarian diet had lower serum phosphorus levels as well as other markers of improved phosphorus metabolism.” “Asking [patients] to eat more grains and less meat and less prepared or packaged foods may lead to increased dietary adherence and improved phosphorus homeostasis.”  

Patients with advanced chronic kidney disease are in positive phosphorus balance, but dietary restriction of phosphate is difficult because of the high phosphate content from dairy products and meat that form the basis of the typical Western diet.

Some research has shown that grain-based vegetarian diets may lead to decreased phosphorus absorption compared with meat-based diets.

So the researchers conducted a crossover trial among nine patients who had a mean estimated glomerular filtration rate (eGFR) of 32 ml/min to compare vegetarian and meat diets with equivalent nutrients. A total of eight patients completed both arms of the study.

The researchers found that just a week of the vegetarian diet led to lower serum phosphorus levels and decreases in fibroblast growth factor 23 (FGF23), which helps regulate phosphorus metabolism, compared with a meat-based diet.

After a week on each of the diets, there were higher serum phosphorus and FGF23 levels, as well as lower parathyroid hormone levels, in the meat diet compared with the vegetarian diet.

Urinary phosphorus excretion was greater in the meat diet group but didn’t reach significance, the researchers said.

The researchers found significantly higher levels of average serum phosphorus (P<0.0001), calcium (P=0.0001), and fractional excretion of phosphorus (P=0.0001) with the meat-based diet. And, again, they saw lower parathyroid hormone levels with that diet as well (P=0.0002).

The study demonstrates the importance of the protein source of phosphate in overall mineral metabolism after only seven days of controlled diets.

They concluded that dietary counseling of patients with chronic kidney disease should include information “on not only the amount of phosphate but also the source of protein from which the phosphate derives.”

They said if the findings are confirmed in future studies, it may provide a rationale for recommending that patients with kidney disease derive their protein sources from a predominantly grain-based vegetarian diet.

“This will allow increased protein intake without adversely affecting phosphorus levels,” they wrote.

Moe SM, et al “Vegetarian compared with meat dietary protein source and phosphorus homeostasis in chronic kidney disease” J Am Soc Nephrol 2010; DOI: 10.2215/CJN.05040610.