Should Salt Intake Be Restricted?
Yes, salt intake should be restricted to less than 5-6 grams per day (approximately 2000-2400 mg sodium) for the general population, with more aggressive targets of less than 5 grams per day for patients with hypertension, and ideally as low as 2 grams sodium per day for those with established cardiovascular disease or chronic kidney disease. 1, 2
Evidence-Based Rationale for Salt Restriction
The global consensus across major hypertension guidelines from 2024 is remarkably consistent: dietary sodium reduction is a cornerstone intervention for blood pressure control and cardiovascular disease prevention. 1
Blood Pressure and Cardiovascular Benefits
Reducing sodium intake by approximately 80 mmol (1.8 g) per day lowers systolic blood pressure by approximately 4 mmHg and diastolic blood pressure by 2 mmHg in hypertensive patients, with smaller but meaningful reductions in normotensive individuals. 2
The 2021 Salt Substitute and Stroke Study (SSaSS) demonstrated significant reductions in blood pressure, cardiovascular disease, and death among Chinese adults who reduced dietary sodium intake from approximately 5 g/day down to 4 g/day. 3
Salt reduction prevents hypertension development by approximately 20% in at-risk individuals, as documented in the Trials of Hypertension Prevention. 2
Beyond blood pressure effects, high salt intake is directly related to left ventricular hypertrophy independent of blood pressure, which is an important risk factor for heart failure. 4
Specific Sodium Intake Targets by Population
General Population
- The World Health Organization and multiple international hypertension societies recommend limiting salt intake to less than 5-6 grams per day (equivalent to approximately 2000-2400 mg sodium per day). 1, 2
Hypertensive Patients
Japanese Society of Hypertension (2019): Restrict salt intake to less than 6 g/day, with a lower limit of 3 g/day as a guide, because extreme salt restriction could be harmful. 1
Chinese Hypertension League (2018): Reduce salt intake to less than 2 g sodium or less than 5 g salt per day. 1
Korean Society of Hypertension (2018): Restrict salt intake to less than 6 g salt per day (≤100 mmol/day sodium, 2.4 g Na). 1
Singapore Hypertension Society (2016): Reduce salt intake to less than 6 g/day for primary prevention and less than 4 g/day for secondary prevention. 1
High-Risk Populations
More aggressive targets of 1500 mg sodium per day are recommended specifically for blacks, middle-aged and older adults, and individuals with hypertension, diabetes, or chronic kidney disease. 2
Blacks and other racial minorities show particularly strong blood pressure responses to dietary salt modification and should be prioritized for salt reduction interventions. 2
Chronic Kidney Disease Patients
Malaysian Society of Nephrology (2018): Restrict sodium intake to less than 2400 mg/day (1 teaspoon of table salt). 1
Indian nephrologists (2017): Lower salt intake to less than 90 mmol/day (less than 2 g sodium), which corresponds to 5 g of NaCl, unless contraindicated. 1
For patients on maintenance hemodialysis, fluid and salt intake should be such that interdialytic weight gain does not exceed 1-1.5 kg. 1
Complementary Dietary Modifications
Potassium Enhancement
Increase potassium intake to approximately 3000-4700 mg per day through fruits, vegetables, and low-fat dairy products. 1, 2
The Japanese Society of Hypertension recommends a daily potassium intake of at least 3000 mg. 1
For patients with normal renal function, increasing dietary potassium can reduce systolic blood pressure by 4-8 mmHg in patients with hypertension. 1
Potassium-Enriched Salt Substitutes
Potassium-enriched salt substitutes (typically 75% sodium chloride and 25% potassium chloride) can be used to increase potassium intake in patients without renal impairment. 1, 5
The Chinese Hypertension League recommends that individuals with good kidney function can choose low-sodium potassium-rich alternative salts. 1
DASH Diet Pattern
- Follow the Dietary Approaches to Stop Hypertension (DASH) diet pattern, which emphasizes vegetables, fruits, and low-fat dairy products while being reduced in saturated fat. 2
Critical Contraindications and Cautions
Potassium-Related Risks
Potassium-enriched salt substitutes and increased dietary potassium are contraindicated in patients with advanced chronic kidney disease, those taking potassium-sparing diuretics, or those on ACE inhibitors/ARBs with impaired renal function. 1, 5, 2
Patients with renal impairment should consult a physician before increasing potassium intake. 1
Lower Limits of Salt Restriction
The Japanese Society of Nephrology recommends setting a lower limit of 3 g/day as a guide because extreme salt restriction could be harmful. 1
While aggressive salt reduction is beneficial, there is some debate about whether achieving less than 1.5 g/day sodium is feasible in real-world settings and whether this low an intake may be harmful. 3
Addressing the Controversy
The J-Curve Debate
Some observational studies have suggested a J-shaped relationship between sodium intake and cardiovascular outcomes, raising concerns about very low sodium intake. 6 However, this evidence is substantially weaker than the intervention trial data supporting salt reduction. 3, 4, 7
The 2024 consensus from Current Opinion in Cardiology concludes that aiming for sodium intakes of 2-3 g/day in the general population and as low as 2 g/day in persons with hypertension or cardiovascular disease seems most reasonable. 3
The SSaSS trial (2021) largely puts to rest any remaining debate about the benefits of dietary sodium restriction among persons with excess baseline intake. 3
Practical Reality
Current estimated dietary intake of salt is about 9-12 g per day in most countries of the world, which is significantly above the WHO recommended level of less than 5 g salt per day. 8, 4
Any meaningful strategy to reduce salt intake must rely on food manufacturers reducing the amount added during food processing, as most dietary sodium comes from processed foods rather than salt added at the table. 2
Implementation Strategy
For Hypertensive Patients
- Target less than 5-6 g salt per day (2000-2400 mg sodium) as the initial goal. 1
- Increase dietary potassium through 4-5 servings of fruits and vegetables daily (providing 1500-3000 mg potassium), unless contraindicated by renal disease or medications. 1, 2
- Consider potassium-enriched salt substitutes if renal function is normal and not taking potassium-sparing diuretics. 1
- Monitor serum potassium and creatinine after 5-7 days when initiating dietary changes, especially if on ACE inhibitors or ARBs. 5
For Heart Failure Patients
Reduce salt intake to less than 5 g/day, as a high salt intake aggravates the retention of salt and water, thereby exacerbating heart failure symptoms and progression of the disease. 4
If salt intake is successfully reduced, there may be a need for reduction in diuretic dosage. 4
For CKD Patients
Implement strict dietary potassium restriction to less than 2000-3000 mg/day if hyperkalemia is present, and restrict high-potassium foods such as bananas, oranges, avocados, potatoes, spinach, and tomato products. 9
Sodium restriction to less than 2300 mg/day is essential for blood pressure control and volume management in patients with acute kidney injury. 9
Common Pitfalls to Avoid
Do not recommend potassium supplements or potassium-enriched salt to patients with advanced CKD (stages 4-5), those on potassium-sparing diuretics, or those with documented hyperkalemia. 1, 5, 9
Do not aim for sodium intake below 3 g/day without careful monitoring, as extreme salt restriction may be harmful. 1, 3
Do not forget to check baseline renal function and serum potassium before recommending increased dietary potassium or potassium-enriched salt substitutes. 5, 9
Do not overlook medication interactions—ACE inhibitors, ARBs, and potassium-sparing diuretics all increase hyperkalemia risk when combined with increased dietary potassium. 5, 9