Protein restriction and body composition in renal disease

To study the effect of low-protein diet (LPD) on body composition (BC).

A systematic review of the literature investigating BC during LPD treatment using total body potassium, dual energy X-ray absorptiometry, bioelectrical impedance analysis, and anthropometry.

Studies reporting data of patients treated with LPD 0.3-0.75 g/kg/day and a renal function of glomerular filtration rate (GFR) < or =20 mL/min, creatinine clearance < or =25 mL/min, on serum creatinine > or =500 micromol/L were included in the review. Fourteen studies with a total number of 666 subjects were found eligible.

All studies except two concluded that treatment with LPD does not affect BC negatively. However, LPD should not be introduced in patients with a complicating disease, e.g., acidosis, septicaemia, and surgical treatment; neither should it be continued in patients who are unable to adhere to a diet prescription. Furthermore, LPD should be introduced with great caution in patients with an expected time to dialysis of < or =4 months due to an initial reduction of body weight and/or fat-free mass. Monitoring of treatment with LPD must be emphasized, including BC measurements and evaluation of protein and energy intake. These conclusions do not apply to patients with diabetes mellitus, because this diagnosis was excluded in a majority of reviewed studies.

There is no strong evidence that LPD impairs BC in patients with GFR < or =20 mL/min.