December 4, 1995
NOTE: There is no standard printed diet that can be mailed to you. Dr. Mackenzie Walser, the study's lead author, recommends working with your physician to tailor a diet specific to your needs. Your physician can reach Dr. Walser with any questions at 410-955-3832.
Johns Hopkins scientists have found that a low-protein diet before dialysis may prolong the lives of kidney failure patients during the first two years on dialysis. The findings also suggest the diet may postpone the start of dialysis for some patients.
The Hopkins team studied 44 patients placed on a special supplemented diet and given dietary counseling at least four months before dialysis began. During the first two years of dialysis, two patients died. National statistics predict 11 to 12 deaths in a group this size.
"This study suggests that changes in pre-dialysis care could reduce the number of deaths on dialysis substantially," says Josef Coresh, M.D., Ph.D., the study's lead author and an assistant professor of epidemiology.
Protein restriction, with or without dietary supplements, has long been studied as a way to slow the progress of kidney failure. But this study, funded by the National Institutes of Health, is the first to show the death rate on dialysis is lowered by a very low-protein diet with ketoacid and amino acid supplements and close clinical monitoring before dialysis, the scientists say.
"The diet not only worked but also prevented protein malnutrition in most patients. In some cases, it reversed it," says Coresh.
The results of the research, which are published in the current issue of the Journal of the American Society of Nephrology, suggest that a broader study of the diet is now warranted, says Mackenzie Walser, M.D., the study's senior author and a professor of medicine and pharmacology. Researchers cannot explain why the restrictive diet helps but say it appears to prepare patients for the rigors of dialysis. The 44 study patients ate no meat, fish, poultry, eggs, milk or cheese. They took tablets of amino acids or synthetic substitutes to make up for the lack of essential components normally provided by protein.
The kidneys filter the blood, reabsorb important components and excrete in the urine the protein breakdown product urea and excess minerals, toxins and fluid. Low levels of protein in the blood are a strong predictor for death in dialysis patients. An earlier Hopkins study showed that the scientists' very low-protein diet produces normal, rather than low, levels of bloodstream protein at the start of dialysis.
"We think the diet eliminates some component of some high-protein foods that makes it difficult for kidney patients to metabolize protein properly," says Walser.
The diet can be followed by most chronic kidney failure patients, and the essential amino acid supplements are commercially available and cheaper than the food items they replace, according to Walser.
For the past decade, the number of kidney failure patients has increased about 11 percent annually. About 200,000 people currently undergo dialysis, a technique to remove waste products and excess fluid from the body as a treatment for kidney failure. About 80,000 Americans die of complications each year on dialysis.
The study looked at former patients of Walser, who treats patients whose kidneys are failing but not shut down. The comparison of death rates was adjusted for age, gender, race and cause of kidney failure. Sylvia Hill, a Hopkins technician, is co-author of the study.