Who benefits from salt restriction?
The strongest evidence for benefit comes from people in the early to moderate stages of chronic kidney disease (CKD stages 1–3). A 2024 randomized controlled trial of 194 patients with CKD stages 1–3 found that those assigned to a low-salt diet (1.5 g/day) lost significantly less kidney function over 3 months: their eGFR dropped by about 3 mL/min/1.73m² less than the control group [1]. This is a meaningful difference because eGFR decline is the main marker of kidney disease progression.
A 2022 meta-analysis that pooled 33 studies (over 100,000 participants) found that a low-salt diet reduced the risk of a composite kidney outcome—including a 50% drop in eGFR, doubling of serum creatinine, or end-stage kidney disease—by 28% (risk ratio 0.72) [2]. This is the largest and most comprehensive analysis among the studies here, and it supports the idea that salt restriction helps prevent the worst kidney outcomes.
The Cochrane review (2021) adds high-certainty evidence that salt reduction lowers blood pressure by about 7/4 mmHg and reduces albuminuria (a marker of kidney damage) by 36% in early-stage CKD [3]. These are the mechanisms thought to protect the kidneys.
When might salt restriction be harmful?
Salt restriction is not safe for everyone. A 2025 study in rats treated with candesartan (a common blood pressure medication) found that a very low-salt diet caused acute kidney injury, with increased serum creatinine and abnormal kidney tissue [4]. The authors concluded that adequate salt intake is essential for maintaining kidney function when taking this class of drugs (angiotensin receptor blockers).
Similarly, a 2025 study of 308 kidney transplant recipients found that a low-salt diet was linked to a faster annual decline in kidney function (eGFR slope), with an adjusted odds ratio of 2.40—meaning those on low salt were more than twice as likely to have rapid kidney decline [7]. The authors suggest that the standard salt restriction advice may need to be reconsidered for transplant patients, especially those on calcineurin inhibitors.
These two studies [4][7] highlight that the relationship between salt and kidney health is not one-size-fits-all. The benefits seen in early CKD may not apply to people on certain medications or after transplantation.
How much salt is the right amount?
The studies here do not agree on a single optimal target. The 2024 trial used a very low target of 1.5 g/day (about 600 mg sodium) and saw benefits [1]. But a 2020 Mendelian randomization study—which uses genetics to mimic a randomized trial—found that higher sodium excretion (estimated at 2.6 g/day for women and 3.7 g/day for men) was actually associated with better kidney function and lower CKD risk [5]. This suggests that the current recommendation of less than 2 g of sodium per day may be too strict for some people.
A 2022 review on nutrition in CKD warns that too strict salt restriction can reduce quality of life and lead to protein-energy wasting (a dangerous loss of muscle and fat) [6]. The author emphasizes that dietary changes must be palatable and sustainable, and that expert dietitian guidance is key.
Taken together, the evidence suggests that moderate salt reduction (e.g., avoiding processed foods and not adding salt at the table) is likely beneficial for early CKD, but extreme restriction (below 1.5–2 g/day) may be harmful for some groups, especially those on certain blood pressure medications or after kidney transplant.
About These Sources
This answer is built on 7 peer-reviewed studies — published from 2020 to 2025, 3 from 2024 or later, 2 in Q1 journals, collectively cited 150 times — selected as the most relevant from 7 studies that passed quality screening, drawn from 84 papers retrieved from a database of over 500 million.
Sources used in this answer
Effect of a Low Salt Diet on the Progression of Chronic Kidney Disease: A Prospective, Open-Label, Randomized Controlled Trial
In a randomized controlled trial of 194 patients with CKD stages 1–3, a low-salt diet (1.5 g/day) for 3 months significantly slowed eGFR decline (mean reduction -3.01 mL/min/1.73m² less than control) and lowered blood pressure more than usual diet.
Effect of a low-salt diet on chronic kidney disease outcomes: a systematic review and meta-analysis
A meta-analysis of 33 studies (101,077 participants) found that a low-salt diet reduced the risk of renal composite outcome events (e.g., 50% eGFR decline, kidney failure) by 28% (RR 0.72), but did not significantly affect eGFR decline rate, proteinuria, or mortality.
Altered dietary salt intake for people with chronic kidney disease
A Cochrane review of 21 randomized controlled trials (1,197 participants) found high-certainty evidence that salt reduction lowers blood pressure by ~7/4 mmHg and reduces albuminuria by 36% in early CKD, but notes studies were too short to assess long-term kidney outcomes.
Adequate salt intake is essential for candesartan-treated rats to maintain renal function.
In a rat study, a very low-salt diet (0.02%) combined with candesartan (an ARB) caused acute kidney injury (increased serum creatinine, abnormal kidney tissue), while moderate salt reversed the damage, suggesting salt restriction can be harmful in this context.
Mendelian Randomization Analysis Reveals a Causal Effect of Urinary Sodium/Urinary Creatinine Ratio on Kidney Function in Europeans
A Mendelian randomization study in Europeans (N up to 567,460) found that higher urinary sodium/creatinine ratio (reflecting higher salt intake) was causally associated with higher eGFR and lower CKD risk, challenging the idea that salt restriction universally protects kidney function.
Nutrition and quality of life in chronic kidney disease patients: a practical approach for salt restriction
A narrative review on nutrition in CKD argues that salt restriction is important but must be balanced against quality of life and risk of protein-energy wasting; too strict restriction may be counterproductive.
Correlation between dietary salt intake and renal outcomes related to calcineurin inhibitor nephrotoxicity in kidney transplant recipients
In a retrospective study of 308 kidney transplant recipients, a low-salt diet was associated with a faster annual decline in eGFR (adjusted odds ratio 2.40), suggesting that standard salt restriction advice may need reassessment for this population.