Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=215468
Story Retrieval Date: 5/19/2013 8:16:21 AM CST
Eating more fruits and vegetables may help protect the kidneys by reducing kidney injury and metabolic acidosis in patients suffering from late-stage kidney disease, according to new research from Texas A&M University.
The study published in the Clinical Journal of the American Society of Nephrology on Thursday observed that chronic kidney disease patients who added fruits and vegetables to their diets experienced a reduction in acidity levels in the body. Deviating from a Western-based diet, typically rich in grain and animal byproducts, may be an effective alternative to the traditional therapies currently used to combat metabolic acidosis, an unhealthy buildup of acid in the body.
“The way that we eat acid is primarily in the form of animal protein,” said Dr. Donald Wesson, vice dean of Texas A&M College of Medicine, a nephrologist and co-author on the study.
“Vegetable protein, although there are some exceptions, largely is metabolized to yield base, or bicarbonate,” he said. “Animal protein is metabolized by the body to yield acid.”
Patients in this study, who were from lower income levels, were given a variety of fruits and vegetables from surplus provided by local farmers. They were usually given apples, raisins, potatoes and spinach to achieve lower acid levels.
Nephrologists, doctors who specialize in kidney health, are so concerned about acidosis in their patients because the more acid that exists in the bloodstream, the harder the kidneys have to work to remove it. For chronic kidney disease patients, this extra strain can increase kidney injury, metabolic acidosis and quicken the need for dialysis and transplantation.
“The intervention reduced the rate of decline but did not stop the decline…on average by about 20-30 percent,” Wesson said. “That avoids the cost of dialysis, which is now $80,000 per year. If you can delay it for five years, you’ve saved the healthcare system $400,000.”
Researchers were testing the idea that a diet rich in fruits and vegetables could be a plausible alternative therapy to bicarbonate pills, which are currently used to treat patients with extreme metabolic acidosis.
“[Bicarbonate] is not a palatable medication,” said Dr. Daniel Batlle, a nephrologist at Northwestern University’s Feinberg School of Medicine. “Patients literally hate it and they have to learn all kinds of tricks to take it.”
After one year, doctors compared patients who increase fruit and vegetable intake with those who took alkali supplement therapy, such as bicarbonate and citrate. They observed that between the two groups, kidney function was similar and urine measurements of kidney injury were lower.
Still, the bicarbonate therapy seemed to come out on top because doctors were hesitant to suggest an equal bicarbonate amount of vegetables and fruits due to the risk of raising potassium levels to dangerous levels. Patients with diminished kidney function have difficulties excreting potassium from their bodies, according to Wesson
“We chose our patients very carefully to choose patients that were at low risk for developing potassium overload,” he said. “Those who seemed to be at moderate to high risk of developing potassium overload, we excluded from the study.”
However, both Wesson and Batlle agreed that this relatively small, preliminary study of less than 100 patients needs more trials before doctors can make definitive claims about the validity of using dietary therapies.
“There are so many different angles and different studies that need to be done,” Batlle said. “Right now we need to focus on the idea of whether alkali is good for the kidneys and if so, what is the best way to give it.”