THURSDAY, May 31 (HealthDay News) — High protein, Atkins-type
diets don’t cause noticeable harm to the kidneys in healthy patients
without kidney disease, a new study indicates.
“There has been concern for decades about possible damaging effects of
high-protein diets on the kidney,” said Dr. Allon Friedman, an associate
professor of medicine at the Indiana University School of Medicine,
Indianapolis. It was thought that excess protein “can rev up the filtering
mechanism in the kidney, causing damage over time,” he explained.
To see whether those fears were founded, Friedman and his team compared
the effects on renal function of a low-carbohydrate, high-protein diet
with those of a standard low-fat, calorie-restricted diet. For two years,
they followed 307 obese men and women, half of whom followed the
high-protein diet, and half assigned to the low-fat plan. None had kidney
disease.
For the high-protein diet, the researchers used guidelines from “Dr.
Atkins’ New Diet Revolution,” which limits carbohydrates while permitting
unlimited fat and protein intake. In the low-fat group, women were
instructed to consume 1,200 to 1,500 calories a day, and men, 1,500 to
1,800 calories daily. They ate about 55 percent of calories from carbs, 30
percent from fat and 15 percent from protein.
The researchers then measured markers of kidney function.
“For otherwise healthy obese people, we did not find that a
low-carbohydrate, high-protein diet was dangerous to kidney heath or put
people at increased risk for that two-year period,” he said.
“One of the take-home messages is, the fact that you lose weight is
more important than how you get there,” Friedman added.
However, it is unknown whether the results would hold longer than two
years or apply to people with chronic conditions such as diabetes, high
blood pressure or kidney disease, Friedman said.
The study, supported by U.S. National Institutes of Health grants, is
published online May 31 and in the July print issue of the Clinical
Journal of the American Society of Nephrology.
Weight loss was similar for both groups. By 24 months, the dieters had
lost about 7 percent of body weight on average.
“Both groups had a drop in the protein in their urine,” Friedman said.
Excess protein in the urine can indicate kidney problems.
Many participants dropped out before the end of the study. At two
years, only 74 of the low-carb group and 83 of the low-fat group completed
the blood test measurements.
Connie Diekman, director of university nutrition at Washington
University in St. Louis, called the study “an interesting first look at an
issue of longstanding concern, high-protein diets and renal function.”
Still more research is needed, she said, including a study to compare a
high-protein diet in healthy individuals free of kidney disease with those
who have a family history of kidney problems.
Because the findings don’t apply to those with kidney problems, “I
would caution people with a history of renal [kidney] problems about the
potential impact of high protein on the health of the kidney,” Diekman
said.
Diet plans should be developed on an individual basis, she said.
The authors said longer follow-up would help determine effects on
kidney function over a longer period, and Friedman said he hopes to look
at the effect of high-protein diets on those who have kidney disease.
The Atkins weight-loss program had no role in the study.
More information
To learn more about kidney disease, visit the National Kidney Foundation.
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