Sodium intake and chronic kidney disease
What it found
In people with chronic kidney disease, cutting salt lowered blood pressure and protein in urine.
Whether that improves long-term heart and kidney outcomes is still unclear.
What they found
Studies in people
Blood pressure in CKD
In a meta-analysis of nine trials in 738 people with chronic kidney disease, cutting salt by about 4.4 grams a day lowered systolic blood pressure by 4.9 mmHg and diastolic by 2.3 mmHg. Ambulatory blood pressure also fell.
Protein in urine
In seven of eleven studies, lower salt intake was linked to a drop in protein in urine of 0.4 grams a day. Lower salt also boosted the protein-lowering effect of blood pressure drugs called RAAS blockers.
Long-term outcomes unclear
Some long-term studies found that higher sodium intake was linked to more kidney disease progression and heart problems. Others found no link between low salt intake and better kidney outcomes.
Sodium sensitivity in CKD
In a classic experiment, raising sodium intake from 20 to 120 mmol a day in people with advanced kidney failure caused a significant rise in blood pressure. The same increase in healthy people caused no change.
Dialysis patients
In a meta-analysis of four trials in dialysis patients, those with lower salt intake had significantly lower systolic and diastolic blood pressure than those with higher intake. In peritoneal dialysis, overhydration was common and linked to higher mortality risk.
Sodium storage in skin
Studies using special MRI scans found that sodium can be stored in the skin. In 99 people with chronic kidney disease, higher skin sodium was strongly linked to a larger heart muscle, independent of blood pressure.
What the authors conclude
“The negative effects of sodium on BP values are amplified in CKD patients, as a result of fluid overload and of direct toxicity on the heart, the vascular system, and kidney.”
Also in their conclusions
- They conclude that reducing salt intake is crucial for people with high blood pressure and chronic kidney disease, from early stages through end-stage kidney disease.
- They advise that salt restriction should be personalized, taking into account volume status and true blood pressure measured by ambulatory monitoring.
- They state that more studies are needed to improve long-term adherence to a low salt diet.
How it was done
High blood pressure is common in chronic kidney disease and is often blamed on the body holding onto sodium and fluid. The authors wanted to review how sodium affects blood pressure from early kidney disease through end-stage kidney disease, and what the evidence says about restricting salt.
They reviewed studies of sodium intake and low salt diets in people with chronic kidney disease, including a meta-analysis of nine trials in 738 patients, a large observational study of 3757 patients followed for almost seven years, and trials in dialysis patients.
What it can’t tell you
- This is a review of other studies, not a single new experiment. It cannot prove that salt restriction directly causes better long-term heart or kidney outcomes.
- Many of the long-term studies were not designed to test low salt diets, and some measured sodium intake only once, which can make the results less reliable.
- The review cannot say whether the blood pressure and proteinuria improvements seen with low salt diets will definitely lead to fewer heart attacks, strokes, or kidney failure.
Who paid
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- Advanced Surgical and Medical Sciences Department of University of Campania "Luigi Vanvitelli", Italy; "Magna Grecia" University, Italy
The paper
- Title
- Sodium Intake and Chronic Kidney Disease
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Borrelli S, Provenzano M, Gagliardi I, et al (2020). Sodium Intake and Chronic Kidney Disease. International journal of molecular sciences. doi:10.3390/ijms21134744Free full textPubMed 32635265DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error