How much does cutting salt actually lower your blood pressure?
The effect is substantial and consistent. In a large trial of over 1,600 older adults in eldercare facilities, replacing regular salt with a salt substitute (62.5% sodium chloride, 25% potassium chloride) lowered systolic blood pressure by an average of 7.1 mmHg and diastolic by 1.9 mmHg over two years [1][2]. This is comparable to the effect of some single blood pressure medications.
A dose-response meta-analysis of 85 trials found a roughly linear relationship: for every 100 mmol reduction in 24-hour urinary sodium (equivalent to about 2.3 grams of salt), systolic blood pressure fell by about 6.8 mmHg in people already on blood pressure medication [4]. The effect was even stronger in those taking beta-blockers or renin-angiotensin system inhibitors.
A separate crossover trial in 213 adults aged 50–75 found that switching from a high-sodium diet (about 2,200 mg added daily) to a low-sodium diet (about 500 mg total daily) lowered mean arterial pressure by a median of 4 mmHg, with 73% of participants experiencing a drop [5]. The average systolic difference between the two diets was 8 mmHg.
Does salt reduction work if you already take blood pressure medication?
Yes, it works independently of medication. The 2023 crossover trial found that the blood pressure reduction from a low-sodium diet was similar in people with controlled hypertension (on medication), uncontrolled hypertension, and untreated hypertension [5]. The effect was consistent across age, sex, race, and body mass index.
A 2024 meta-analysis specifically in treated hypertensive patients confirmed a clear dose-response relationship: reducing sodium intake lowered blood pressure regardless of baseline blood pressure levels or study duration [4]. The effect was modified by the type of medication, with the largest drops seen in those on beta-blockers and renin-angiotensin system inhibitors.
However, one study in older adults with physical frailty (average age 76) found no association between salt intake and blood pressure in that subgroup [6]. This suggests that for very frail older adults, other factors like nutrition and frailty itself may dominate blood pressure control, and salt reduction should be approached cautiously to avoid malnutrition.
Is using a salt substitute better than just trying to eat less salt?
Yes, salt substitutes appear more effective than simply restricting salt supply. In the DECIDE-Salt trial, replacing regular salt with a potassium-enriched substitute lowered systolic blood pressure by 7.1 mmHg and reduced major cardiovascular events by 40% (hazard ratio 0.60) over two years [1][2]. In contrast, progressively restricting the amount of salt provided to kitchens had no significant effect on blood pressure or health outcomes.
The salt substitute also proved cost-saving: it saved an average of $26 per participant over two years, mainly by preventing costly cardiovascular events like strokes and heart attacks [1]. If rolled out to all eldercare facilities in China, the study estimated it could prevent over 48,000 major cardiovascular events and 107,000 hypertension cases, while saving $55 million in healthcare costs.
A smartphone app designed to help people choose lower-sodium packaged foods, combined with reduced-sodium salt, did not significantly lower sodium intake or blood pressure in a 2023 trial, likely because participants did not use the app enough [3]. This highlights that the method of delivery matters: passive tools like salt substitutes work better than tools requiring active engagement.
Sources used in this answer
Cost-Effectiveness of Salt Substitute and Salt Supply Restriction in Eldercare Facilities
Salt substitute reduced systolic blood pressure by 7.14 mmHg, hypertension prevalence by 5.09 percentage points, and major cardiovascular events by 2.27 percentage points over 2 years in eldercare residents, while saving $26 per participant in healthcare costs.
Salt substitution and salt-supply restriction for lowering blood pressure in elderly care facilities: a cluster-randomized trial
Salt substitute lowered systolic blood pressure by 7.1 mmHg and reduced cardiovascular events by 40% (HR 0.60) in elderly care facilities, while salt supply restriction had no effect on blood pressure.
Effectiveness of a Sodium-Reduction Smartphone App and Reduced-Sodium Salt to Lower Sodium Intake in Adults With Hypertension: Findings From the Salt Alternatives Randomized Controlled Trial
A smartphone app plus reduced-sodium salt did not significantly reduce 24-hour urinary sodium excretion or blood pressure in adults with hypertension, possibly due to low engagement.
Blood Pressure-Lowering Medications, Sodium Reduction, and Blood Pressure.
For every 100 mmol reduction in 24-hour urinary sodium, systolic blood pressure decreased by 6.81 mmHg in treated hypertensive individuals, with greater effects seen with beta-blockers and renin-angiotensin system inhibitors.
Effect of Dietary Sodium on Blood Pressure
A low-sodium diet (500 mg/day) lowered mean arterial pressure in 73.4% of middle-aged to older adults compared to a high-sodium diet, with an average systolic difference of 8 mmHg, independent of hypertension status or medication use.
Association between salt intake and blood pressure among community-dwelling older adults based on their physical frailty status
Among 1,975 community-dwelling older adults, salt intake was associated with systolic blood pressure only in those without physical frailty and not on antihypertensives; no association was seen in frail older adults.