#386 The Bland Supremacy: Salt and cardiovascular disease
CLINICAL QUESTION
Does reducing sodium intake or substituting table salt with sodium-potassium alternatives improve cardiovascular outcomes?
BOTTOM LINE
Based on one large randomized, controlled trial (RCT) in patients with hypertension/previous stroke with above average daily salt intake (example 4.8 g/day), replacing table salt with a salt substitute may decrease mortality (from ~4.5% to ~4%) and stroke (from ~3.5% to 3%) per year. Whether reducing sodium by other means reduces mortality or cardiovascular events is unknown.
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EVIDENCE
- Results statistically significant unless indicated.
- Table salt substitution (75% sodium-chloride/25% potassium-chloride), largest RCT:1
- 20,995 participants from rural China (age ~65, mean blood pressure ~154/89, 73% with stroke history, sodium intake ~4.8g at baseline),2 estimated incidence per year:
- Mortality: ~4% (salt substitution) versus ~4.5 % (usual salt), Number Needed to Treat (NNT)=200.
- Strokes: ~3% (salt substitution) versus ~3.4 % (usual salt), NNT=250.
- Systolic blood pressure: Reduced by 3.3mmHg (salt substitution) compared to continuing regular salt.
- Limitation: Likely higher than average salt intake.
- 20,995 participants from rural China (age ~65, mean blood pressure ~154/89, 73% with stroke history, sodium intake ~4.8g at baseline),2 estimated incidence per year:
- Four systematic reviews (including above trial) showed similar results for mortality.3-6
- Adverse effects:
- Serum potassium: 0.12-0.18mmol/L higher with salt substitution.3,6
- Overall, few cases severe hyperkalemia/worsening renal function. 3,6
- Limitations: Severe kidney disease excluded.1
- Sodium reduction: No RCT powered to detect change in mortality/cardiovascular events.7,8
CONTEXT
- Guidelines:
- Recommend sodium reduction (example: <2g/day) but there is no reliable way for patients to estimate sodium consumption.9
- Average sodium intake (Canadians): ~2.7-3.6g/day.10,11
- In Canada, 75% sodium-chloride/25% potassium-chloride not available. Products with different blends of salt and potassium chloride (containing 50% less sodium than regular salt) are available (example: Half-SaltTM).
- Blood pressure:
- RCT: Lowering sodium intake (~3.6 to ~2.6 grams/day) reduces BP by ~4mmHg at 2.5 years.7,8 However, this was achieved with coaching to reduce sodium; unknown if brief interventions/self-help materials helpful long-term.
- Effect of sodium substitution/reduction on blood pressure is comparable to blood-pressure medications.12
- If processed food important source of sodium intake (common in North America, but not rural China), salt substitution/reduction may have less impact.
- Focusing on healthier food choices important; the Mediterranean diet has been shown to reduce the risk of cardiovascular events.13
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Confirms my current practice
Good topic
I WORK WITH A DIETITION IN TRYING TO GET PATIENTS TO REDUCE SALT INTAKe.
Confirms my current practice as well.
Old habits die hard. Recommend DASH diet. Joyfully share info. and benefits of herbs, spices, etc. and techniques to flush Na from system.