Chronic kidney disease patients who consumed diets high in animal protein were three times more likely to develop kidney failure in a study than patients who consumed diets high in fruits and vegetables, according to research published in the Journal of the American Society of Nephrology.

Researchers from Texas A&M Health Science Center College of Medicine collected data from 1,486 adults with chronic kidney disease who were participating in the National Health and Nutrition Examination Survey III. The study is believed to be the largest one to look at the long-term impact of diet on kidney disease in humans.

When humans eat animal proteins such as red meat, the body metabolizes these proteins into acids, according to Donald Wesson, MD, an author on the study. The kidneys produce substances to help the body rid itself of this acid, but these substances can hurt kidney function if they remain at high levels in the body over long periods of time.

“It’s like a double-edge sword,” Wesson said. “In the short term these substances can help the kidneys get rid of acid, but in the long-term they can reduce kidney function.”

Wesson has spent more than 30 years studying the impact of diet on kidney disease. His studies have shown that when animals or humans switch from a diet high in animal protein to one high in plant proteins such as fruits and vegetables, kidney function is protected. This is because the body metabolizes plant proteins into bases, not acids.

Wesson currently is a co-investigator on a multi-center, $2 million grant from the National Institutes of Health to conduct a national study to confirm if reducing dietary acid slows or prevents worsening of kidney disease. He said that while studies have yet to prove that eating a diet high in fruits and vegetables can prevent kidney disease, such diets have already been shown to help to maintain overall good health.

He notes that diets high in fruits and vegetables reduce blood pressure, which is very beneficial to patients with chronic kidney disease because most of these patients have higher than normal blood pressure without treatment.

“We know that fruits and vegetables are ‘heart friendly’ and these ongoing studies will help confirm if they are also ‘kidney friendly’,” Wesson said. “Stay tuned.”