Cochrane: People with CKD are at increased risk
of heart disease and deteriorating kidney health which can lead to need
for dialysis or kidney transplantation to survive. Reducing risk of heart disease and preserving kidney function are important treatment goals.
High salt intake is linked to risk factors for both heart disease and worsening kidney function, including high blood pressure, excess protein in the urine (proteinuria) and fluid overload. It is thought to be particularly important for people with CKD to have a low salt intake due to kidneys' role in salt balance. We aimed to find out if altering salt in the diet was beneficial for people with CKD.
We searched the literature for studies that looked at the effects of restricting salt in the diets of people with CKD up to January 2015. We found eight studies that involved 258 people which met our inclusion criteria. Study participants included people in the early stages of CKD (six studies), who were on peritoneal dialysis (one study), or were kidney transplant recipients (one study). The average study duration was six weeks, and ranged from one to 26 weeks. We did not find any studies that measured the effect of salt intake on the incidence of death, heart disease, or need to begin dialysis.
We found that reducing salt intake reduced 24 hour sodium excretion, blood pressure. One study reported restricting salt intake reduced the risk of oedema (swelling). Antihypertensive medication dosage was significantly reduced with a low salt diet. There was no significant difference in kidney function measures or body weight. There was no significant change in total cholesterol or hypotension.
Long-term effects of salt restriction in people with CKD is lacking that meant we were unable to determine the direct effects of sodium restriction on primary endpoints such as mortality and progression to end-stage kidney disease (ESKD). Research into the long-term effects of sodium-restricted diet for people with CKD is warranted, as is investigation into adherence to low salt diet.
High salt intake is linked to risk factors for both heart disease and worsening kidney function, including high blood pressure, excess protein in the urine (proteinuria) and fluid overload. It is thought to be particularly important for people with CKD to have a low salt intake due to kidneys' role in salt balance. We aimed to find out if altering salt in the diet was beneficial for people with CKD.
We searched the literature for studies that looked at the effects of restricting salt in the diets of people with CKD up to January 2015. We found eight studies that involved 258 people which met our inclusion criteria. Study participants included people in the early stages of CKD (six studies), who were on peritoneal dialysis (one study), or were kidney transplant recipients (one study). The average study duration was six weeks, and ranged from one to 26 weeks. We did not find any studies that measured the effect of salt intake on the incidence of death, heart disease, or need to begin dialysis.
We found that reducing salt intake reduced 24 hour sodium excretion, blood pressure. One study reported restricting salt intake reduced the risk of oedema (swelling). Antihypertensive medication dosage was significantly reduced with a low salt diet. There was no significant difference in kidney function measures or body weight. There was no significant change in total cholesterol or hypotension.
Long-term effects of salt restriction in people with CKD is lacking that meant we were unable to determine the direct effects of sodium restriction on primary endpoints such as mortality and progression to end-stage kidney disease (ESKD). Research into the long-term effects of sodium-restricted diet for people with CKD is warranted, as is investigation into adherence to low salt diet.
Authors' conclusions:
We found a critical
evidence gap in long-term effects of salt restriction in people with
CKD that meant we were unable to determine the direct effects of sodium
restriction on primary endpoints such as mortality
and progression to end-stage kidney disease (ESKD). We found that salt
reduction in people with CKD reduced blood pressure considerably and
consistently reduced proteinuria. If such reductions could be maintained
long-term, this effect may translate to clinically significant
reductions in ESKD incidence and cardiovascular
events. Research into the long-term effects of sodium-restricted diet
for people with CKD is warranted, as is investigation into adherence to a
low salt diet.