Posted Tuesday, September 21, 2010 at 10:35 AM
This is from our website NutritionMD.org:
Impaired kidney function. Studies of the Atkins diet and other low–carbohydrate, high–protein diets have not been of sufficient duration to evaluate their potential to affect kidney function. However, reason for concern comes from studies of the general population, in which diets high in animal protein are associated with reduced kidney function over time. Harvard researchers reported that animal protein intake is associated with decline in kidney function, based on observations in 1,624 women participating in the Nurses’ Health Study. The good news is that the damage to the kidneys was found only in those who already had reduced kidney function at the study’s outset. The bad news is that as many as one in four adults in the United States may already have reduced kidney function, and the percentage is considerably higher for those over 40 or who have hypertension. Mild kidney impairment is also found in approximately 40 percent of individuals with diabetes. This suggests that many people who have kidney problems are unaware of that fact and do not realize that high–protein diets may put them at risk for further deterioration. The kidney–damaging effect was seen only with animal protein. Plant protein had no harmful effect.
Source: Knight EL, Stampfer MJ, Hankinson SE, Spiegelman D, Curhan GC. The Impact of Protein Intake on Renal Function Decline in Women with Normal Renal Function or Mild Renal Insufficiency Ann Int Med 2003;138:460-7.
I wouldn't worry about the protein sources you are getting from beans and grains. They tend to act appropriately in the body. That being said, I have to agree that taking a protein supplement of some sort (plant or animal source) is totaly unnecessary and possibly harmful.
Susan Levin, MS, RD
PCRM Director of Nutrition Education