Patients with chronic renal disease have no doubt heard rumblings about low-protein diets. For a long time, the jury was out as to the value of these diets as studies conflicted as to the possible benefit. However, studies indicate that low-protein diets can extend the life of kidneys with chronic disease.
Low-Protein Defined
The National Kidney Foundation recommends that patients with chronic kidney disease, including those with kidney disease due to diabetes, limit dietary protein to 0.8 g per kg of body weight. This means that a 120 lb. adult should consume approximately 44 g of protein daily. A low-protein diet does not mean going to dangerous extremes. Curiously, what doctors call "low-protein" is identical to the daily recommended dietary intake by the USDA.
Rationale
When healthy kidneys filter blood, they keep protein in the blood and remove creatinine, urea and other wastes. However, compromised kidneys are less able to perform this function and proteins get spilled from the bloodstream into the urine. This accelerates the loss of kidney function independently of the underlying kidney disease. Eating a high-protein diet tends to raise the amount of proteins in the blood, which in turn get filtered through the kidneys. By lowering this protein load, the kidneys are exposed to less wear-and-tear.
Evidence
Research results published in the July 2002 issue of "Kidney International" are fairly typical of the studies showing the benefit of a low-protein diet. Researchers studied 82 patients with diabetic kidney disease for a 4-year period, comparing patients who consumed 0.6 g of protein per kg body weight with those who consumed a normal protein diet of approximately 1.02 g of protein per kg body weight. The study results indicated that patients following a lower-protein diet had less risk of renal failure and death than controls.
Warning
Never go on a low-protein diet without consulting your nephrologist. There are many instances in which such a diet is contraindicated. Patients on hemodialysis need more than the recommended daily intake of protein because hemodialysis removes protein from the blood. Children need protein to grow, so low-protein diets are only indicated in extreme circumstances. Patients approaching end-stage disease are often malnourished and additional protein might be indicated.
