Beneficial responses to modified diets in treating patients with chronic kidney disease

In rats, protein-restricted diets prolong survival from experimental chronic kidney disease (CKD). Diets for CKD patients that are restricted in protein and modified to limit the intake of phosphates and sodium not only reduce the accumulation of unexcreted metabolic products but also protect against hypertension and proteinuria. Their ability to slow progression of CKD is controversial, and this fact, plus concern about the nutritional adequacy of restricted diets, has limited this treatment strategy for CKD patients.

Expected responses of CKD patients to dietary manipulation are examined. The influence of this strategy on complications of CKD, including results from the MDRD Study, is analyzed.

Dietary compliance with low-protein diets can be monitored from 24-hour urea excretion. Long-term therapy with diets containing 0.6 g protein/kg/day or less protein supplemented with essential amino acids or their ketoanalogues maintain body weight and normal values of serum proteins while reducing the accumulation of acid, phosphates, urea. Low-protein diets suppress proteinuria even when angiotensin-converting enzyme inhibitors are used. Patients in the MDRD Study who complied with the diet had a significant slowing of the rate of loss of glomerular filtration rate (GFR).

Successful dietary manipulation can ameliorate many complications of CKD. Low-protein diets are nutritionally safe, they reduce the accumulation of metabolic products, and they can suppress progressive loss of kidney function. Dietary manipulation should be an integral part of the therapy for patients with progressive CKD.