Protein intake and oxidative stress
Oxidative stress and upregulation of oxidative metabolism
are among the main factors responsible for sarcopenia in
chronic disease and in aging. Recent data suggest that
oxidative stress is associated with severe disturbances of
muscle function even without muscle atrophy.34 Moreover,
oxidative stress is probably one of the main factors that
aggravate glomerulosclerosis and fibrosis during CKD.
A low-protein intake confers a protection against oxidative
stress in experimental studies.35,36 Finally in CKD patients
treated with LPD or supplemented very low-protein
diet (SVLPD), long-term studies on body composition did
not find any adverse effect of such diets on muscle or lean
body mass.37–39
Quality of protein intake (and not only quantity) should
also be addressed. First, despite debate and controversies,
clinical studies in patients receiving LPD (0.6–0.8 g/kg/day)
or SVLPD (0.3–0.6 g/kg/day, supplemented with amino acids
or keto-analogs) are nutritionally safe. No case of malnutrition
occurred, in response to an adequate metabolic
adaptation.13,17 In the Modification of Diet in Renal Disease
study, 9 months after completion of the study, the mean
serum albumin was 42 g/l, and in the 239 patients of the
Bordeaux cohort, only two patients stopped an SVLPD diet
for reason of malnutrition, whereas the mean cohort serum
albumin at start of renal replacement therapy was 39 g/l.40,41
Beneficial effects of a nutritional support
Most patients who start renal replacement therapy without
prior dietary follow-up do present symptoms of malnutrition,