The American Journal of Physiology, a Bethesda, Md.-based leading scientific journal, plans to publish a study conducted by a group of Heart Institute of Spokane researchers, who found that diets high in protein harm the kidneys, especially in diabetics.


The paper shows that amino acids, which are the organic compounds of protein, injure the small blood vessels of the kidney, says Dr. Katherine Tuttle, director of research at the Institute. High-protein diets, such as the Atkins and Zone diets, produce hypertension in the kidneys, and hypertension leads to progressive kidney disease, she claims. Study findings also show that people who suffer from diabetes, the most common cause of end-stage renal failure, are at greater risk of kidney damage from protein consumption than other people, Tuttle says.


Our work is the first to demonstrate this novel mechanism of injury, Tuttle asserts. She adds that the research will help the scientific community understand kidney and circulatory diseases in diabetics better.


The paper, titled Amino Acids Induce Indicators of Response to Injury in Glomerular Mesangial Cells, is expected to appear in the journal this summer and is posted on its Web site now. Its authored by Tuttle, senior research scientist Rick Meek, and research technologist Sheryl Cooney, all of whom are with the Heart Institute. Also listed as authors are former institute graduate student researchers Stephanie Flynn and Maria Poczatek, research technician Dr. Robert Chouinard, and Joanne Murphy-Ulrich, a professor of pathology in Alabama, none of whom are with the Heart Institute now.


With knowledge from the research, Tuttle is developing and studying a Mediterranean-style diet, which she thinks offers better nutritional balance than other types of diets. Mediterranean diets emphasize grains, fruits, vegetables, legumes, fish, and so called good fat, such as olive oil. Red meat is eaten sparingly in a Mediterranean diet.


Tuttle also is eyeing the possibility of developing a low-protein meal-replacement drink for diabetics. The nutritional supplement would control blood sugar levels, prevent weight gain, and prevent injury to the circulatory system, with a focus on the kidneys, she says.


In recent years, many diabetics, as well as many Americans in general, have turned to high-protein diets and meal-replacement drinks that support those diets, as a quick way to lose weight, she says. The long-term effects, though, cast a shadow on short-term weight-loss results, Tuttle contends.


Very few nutritional products have been subjected to any kind of study, she claims. If a drink were developed for diabetics, wed have the credibility of some science behind the recommendation.


A drink for diabetics could be compared with Gatorade, a popular drink developed by nephrologists at the University of Florida. Those kidney doctors designed the drink to replenish that schools athletes with nutrients after they were weak from sweating in the hot Gainesville, Fla., sun during workouts, Tuttle says.


There are 20 million diabetics in the U.S., and 30 million to 40 million people with kidney disease, who could benefit from a meal-replacement drink geared toward them, she says.


Although development of such a product is a far-off goal, she says.


We havent created anything yet, but were thinking of what that might be, she says.


The kidneys remove waste, filter and clean the blood supply, and maintain chemical and fluid balances in the body. At all times, they hold about 25 percent of the bodys blood supply, Tuttle says.


People often overlook the importance of the kidneys, she says, bewildered that many people confuse them with the liver, which has an entirely different function.


Kidney disease is one of the most important problems in the developed world and diagnosis of it is galloping away at exponential rates, she adds.


The Heart Institute paper fills a lot of gaps as to why high-protein diets are bad for kidneys, Tuttle says. Because amino acids are doing vascular damage to the kidneys, the problems protein causes could extend to other organs and parts of the circulatory system, such as the brain and the heart, she says.


Its possible for hypertension, in which the force of blood, or blood pressure, against the artery walls is too strong, to exist in the kidneys, but not in the rest of the body, Tuttle says.


Yet, although the only organ the study directly addresses is the kidney, it certainly would be a strong hypothesis that the kidney is not the only target of vascular injury, Tuttle says.