Sodium Raises Blood Pressure; Calcium Does Not
Sodium intake directly and significantly raises blood pressure, while there is insufficient evidence that calcium supplementation lowers blood pressure or that calcium deficiency raises it. 1
Sodium's Effect on Blood Pressure
Clear Evidence for Blood Pressure Elevation
Sodium intake is positively associated with blood pressure across migrant, cross-sectional, and prospective cohort studies, accounting for much of the age-related increase in blood pressure. 1
Reducing sodium intake from approximately 3,300 mg/day to 2,400 mg/day lowers blood pressure by 2/1 mm Hg, while reduction to 1,500 mg/day lowers blood pressure by 7/3 mm Hg. 1
Even modest sodium reduction of 1,000 mg/day decreases blood pressure by 3-4/1-2 mm Hg. 1
Magnitude and Clinical Significance
In resistant hypertension, low-salt diet (50 mmol/24 hours) compared to high-salt diet (250 mmol/24 hours) decreased office blood pressure by 22.7/9.1 mm Hg, demonstrating the profound impact of sodium in salt-sensitive individuals. 2
Sodium reduction of approximately 1,000 mg/day reduces cardiovascular events by about 30%. 1
Higher dietary sodium intake is independently associated with increased risk of fatal and nonfatal stroke and cardiovascular disease. 1
Salt Sensitivity
Salt sensitivity is especially common in Black individuals, older adults, and those with higher baseline blood pressure or comorbidities such as chronic kidney disease, diabetes, or metabolic syndrome—collectively representing more than half of all U.S. adults. 1
About 60% of people with hypertension respond to high sodium intake with blood pressure elevation and to sodium restriction with blood pressure reduction. 3
Calcium's Effect on Blood Pressure
Insufficient Evidence
There is insufficient evidence from randomized controlled trials to determine whether reducing sodium intake plus changing dietary intake of calcium lowers blood pressure more than reducing sodium intake alone. 1
The 2013 AHA/ACC guidelines explicitly state insufficient evidence exists to support calcium supplementation for blood pressure reduction. 4
UK NICE guidelines explicitly state that calcium supplements should not be offered as a method for reducing blood pressure. 4
Conflicting and Weak Data
While some dietary factors associated with high blood pressure include insufficient intake of calcium, this is based on observational data showing associations with overall dietary patterns, not calcium supplementation trials. 1
Claims that slight reductions in calcium intake may be important in developing high blood pressure are disputed, with no satisfactory hypothesis explaining how small reductions in dietary calcium could cause hypertension. 5
Three published studies on large increases in calcium intake reported to lower blood pressure are not in agreement with each other. 5
Clinical Recommendations
Sodium Reduction Strategy
Adults who would benefit from blood pressure lowering should consume no more than 2,400 mg of sodium per day. 1
Further reduction to 1,500 mg/day can result in even greater blood pressure reduction. 1
Even without achieving these goals, reducing sodium intake by at least 1,000 mg/day lowers blood pressure. 1
Why Sodium Reduction Takes Priority
Sodium reduction is the primary intervention for blood pressure reduction due to strong and consistent evidence across all populations with a dose-dependent effect. 4
The effect is consistent across all demographic subgroups: women and men, African-American and non-African-American adults, older and younger adults, and those with prehypertension or hypertension. 1, 4
Sodium reduction is safe and effective across all patient populations without the contraindications that limit potassium, calcium, or magnesium interventions. 4
Common Pitfalls
Do not recommend calcium supplementation for blood pressure management—the evidence does not support this intervention. 4
Recognize that most U.S. adults consume 3,500-4,100 mg of sodium daily, far exceeding recommendations, making sodium reduction the most impactful dietary intervention. 1
Be aware that processed foods contribute the majority of dietary sodium; patient education should focus on avoiding processed foods rather than just table salt. 4