Low vs High Sodium Diet for High Blood Pressure

Overseen By Roland James, MA

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Medical College of Wisconsin

Must not be taking: Glucocorticoids, Anticoagulants

Disqualifiers: Diabetes, Heart failure, Kidney disease, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 3

70 Participants Needed

Trial Summary

Will I have to stop taking my current medications?

The trial does not specify if you need to stop taking your current medications, but you cannot participate if you use glucocorticoids or anti-platelet and anticoagulant agents like aspirin.

What data supports the effectiveness of the treatment for high blood pressure?

Research shows that reducing sodium intake can lower blood pressure in the short term. In a study, switching from a high sodium diet to a low sodium diet resulted in a significant drop in blood pressure for both white and black patients. ^{1 2 3 4 5}

Is a low or high sodium diet safe for humans?

Research suggests that reducing sodium intake can lower blood pressure, which is generally safe and beneficial for people with high blood pressure. However, there is limited evidence on the long-term safety of low sodium diets in terms of overall health outcomes like mortality and morbidity, and more studies are needed to confirm these effects. ^{6 7 8 9 10}

How does the low vs high sodium diet treatment for high blood pressure differ from other treatments?

This treatment focuses on adjusting dietary sodium intake, which is unique compared to medications that directly target blood pressure. By reducing sodium, it aims to naturally lower blood pressure, but the long-term effects on overall health are still unclear. ^{1 2 3 4 11}

What is the purpose of this trial?

Salt sensitive hypertension is a significant health problem worldwide and a primary modifiable risk factor for renal, cardiovascular, and cerebrovascular diseases. Yet, the underlying mechanisms remain poorly understood. The proposed study determines how renal oxygenation and substrate metabolism differs between individuals with and without salt sensitivity, with the ultimate goal of identifying mechanisms, diagnostic criteria, and treatment strategies for salt sensitive hypertension.

Research Team

Srividya Kidambi, MD

Principal Investigator

Medical College of Wisconsin

Eligibility Criteria

This trial is for English-speaking individuals with blood pressure levels indicating elevated BP or Stage 1 hypertension, as per the 2017 ACC/AHA guidelines. It's not suitable for those with normal or severe high blood pressure, diabetes, heart failure, liver cirrhosis, electrolyte issues, kidney disease, certain medication use (like glucocorticoids), pregnant/nursing women, bleeding disorders, heavy daily salt intake (>6000 mg/day), metallic implants presence in body including pacemakers.

Inclusion Criteria

My blood pressure is high but not severe, according to the 2017 guidelines.

Exclusion Criteria

You are allergic to shellfish.

You are afraid of small, enclosed spaces.

I have a bleeding disorder.

Timeline

Screening

Participants are screened for eligibility to participate in the trial

1 week

1 visit (in-person)

Low Sodium Diet

Participants follow a low sodium diet (1200 mg/day) for two weeks with food logs and dietary assessments

2 weeks

1 visit (in-person) for BOLD MRI and other assessments

Wash-out

Participants undergo a wash-out period between diet phases

1 week

High Sodium Diet

Participants follow a high sodium diet (>4200 mg/day) for two weeks with sodium chloride supplementation if needed

2 weeks

1 visit (in-person) for BOLD MRI and renal vein sampling for some participants

Follow-up

Participants are monitored for changes in renal oxygenation and metabolites after diet interventions

1 week

Treatment Details

Interventions

• high sodium diet
• Low sodium diet

Trial Overview The study investigates how a low sodium diet versus a high sodium diet affects kidney oxygenation and metabolism in people who are sensitive to salt. This could help understand why some individuals develop high blood pressure when they consume salt and lead to better diagnostic methods and treatments.

Participant Groups

Group I: Low sodium diet Active Control 1 Intervention

-Subjects will be randomized to start a low sodium diet (1200 mg/day) for two weeks (this will be followed by a high sodium diet - crossover design)

Group II: high sodium diet Active Control 1 Intervention

-Subjects will be randomized to start a high sodium diet (4200 mg/day) for two weeks (this will be followed by a low sodium diet - crossover design)

Who Is Running the Clinical Trial?

Medical College of Wisconsin

Lead Sponsor

Trials

645

Recruited

1,180,000+

Findings from Research

Long-term sodium restriction in adults can lead to minimal reductions in blood pressure, with systolic pressure decreasing by an average of 1.1 mm Hg and diastolic pressure by 0.6 mm Hg over follow-ups ranging from 6 months to 7 years across various studies.

Participants on a low sodium diet were able to discontinue their antihypertensive medications more frequently while maintaining similar blood pressure control, suggesting that sodium reduction may support medication management in patients with elevated blood pressure.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Advice to reduce dietary salt for prevention of cardiovascular disease. Hooper, L., Bartlett, C., Davey, SG., et al.[2018]

Long-term sodium restriction in adults can lead to minimal reductions in blood pressure, with systolic pressure decreasing by an average of 1.1 mm Hg and diastolic pressure by 0.6 mm Hg over follow-ups ranging from 6 months to 7 years across various studies.

Participants on a low sodium diet were able to discontinue their antihypertensive medications more frequently while maintaining similar blood pressure control, suggesting that sodium reduction may support medication management in patients with elevated blood pressure.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Reduced dietary salt for prevention of cardiovascular disease. Hooper, L., Bartlett, C., Davey, SM., et al.[2018]

Long-term sodium restriction in adults can lead to minimal reductions in blood pressure, with systolic pressure decreasing by an average of 1.1 mm Hg and diastolic pressure by 0.6 mm Hg over follow-ups ranging from 6 months to 7 years across various studies.

Participants on a low sodium diet were able to discontinue their antihypertensive medications more frequently while maintaining similar blood pressure control, suggesting that sodium reduction may support medication management in patients with elevated blood pressure.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Reduced dietary salt for prevention of cardiovascular disease. Hooper, L., Bartlett, C., Davey Smith, G., et al.[2020]

Long-term sodium restriction in adults can lead to minimal reductions in blood pressure, with systolic pressure decreasing by an average of 1.1 mm Hg and diastolic pressure by 0.6 mm Hg over follow-ups ranging from 6 months to 7 years across various studies.

Participants on a low sodium diet were able to discontinue their antihypertensive medications more frequently while maintaining similar blood pressure control, suggesting that sodium reduction may support medication management in patients with elevated blood pressure.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Reduced dietary salt for prevention of cardiovascular disease. Hooper, L., Bartlett, C., Davey, SM., et al.[2020]

In a study of 104 patients with essential hypertension, black patients experienced a greater reduction in blood pressure (22/10 mm Hg) compared to white patients (17/6 mm Hg) when switching from a high sodium diet to a low sodium diet, indicating a potentially stronger response to sodium restriction in blacks.

The study found that black patients had a less responsive renin-angiotensin-aldosterone system, as evidenced by lower increases in plasma renin activity and angiotensin II levels compared to white patients, which may explain their greater blood pressure reduction with lower sodium intake.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Importance of the renin system in determining blood pressure fall with salt restriction in black and white hypertensives. He, FJ., Markandu, ND., Sagnella, GA., et al.[2022]

Reducing daily sodium intake by 1840 mg could prevent approximately 11,550 cardiovascular disease events annually in Canada, highlighting the significant impact of dietary changes on heart health.

The study suggests that a sodium reduction from 1200 mg to 2400 mg per day could lead to a decrease in cardiovascular events ranging from 8300 to 16,800 per year, emphasizing the importance of sodium intake in managing cardiovascular risk.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Reducing dietary sodium and decreases in cardiovascular disease in Canada. Penz, ED., Joffres, MR., Campbell, NR.[2021]

Reducing dietary sodium intake to recommended levels (no more than 100 mmol per day) is crucial for preventing high blood pressure, especially in individuals at higher risk, such as the overweight, elderly, or those with borderline hypertension.

A low-salt diet, when combined with anti-hypertensive medications, can effectively lower blood pressure across different populations, and dietary changes like increasing potassium, calcium, and magnesium intake further enhance hypertension management.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Salt intake and hypertension therapy. Milan, A., Mulatero, P., Rabbia, F., et al.[2013]

The DASH trial demonstrated that a significant reduction in dietary sodium can lead to a meaningful decrease in blood pressure over a 30-day period, highlighting the importance of sodium intake in managing hypertension.

However, there is currently insufficient evidence linking sodium reduction to improved health outcomes like morbidity and mortality, suggesting that universal sodium reduction recommendations should be approached with caution until more definitive studies are conducted.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Low sodium diet after DASH: has the situation changed? Dietary Approaches to Stop Hypertension. Cohen, HW., Alderman, MH.[2019]

The Satter House Trial of Reduced Sodium Meals (SOTRUE) showed that a low sodium meal plan for 14 days in older adults led to a reduction in seated systolic blood pressure (SBP) from 123 to 112 mmHg, indicating potential benefits for blood pressure management.

While the low sodium diet did lower SBP by 4.8 mmHg compared to a typical sodium diet, the results were not statistically significant, suggesting that further research with a larger sample size and longer duration is necessary to confirm the efficacy and safety of low sodium meals in older adults.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The Effects of a Low Sodium Meal Plan on Blood Pressure in Older Adults: The SOTRUE Randomized Feasibility Trial. Juraschek, SP., Millar, CL., Foley, A., et al.[2021]

Current blood pressure guidelines recommending low sodium intake (<2.3 g/day) may not be supported by strong evidence, as there is no proven effectiveness in reducing cardiovascular disease compared to moderate sodium intake.

Most people consume a moderate sodium range (2.3-4.6 g/day) that does not increase cardiovascular risk, and risks appear to rise only when sodium intake exceeds 5 g/day, suggesting a more reasonable population target of <5 g/day for those with higher intakes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Salt and cardiovascular disease: insufficient evidence to recommend low sodium intake. O'Donnell, M., Mente, A., Alderman, MH., et al.[2021]

In a study of 412 adults with pre- or stage 1 hypertension, combining a low sodium diet with the DASH diet resulted in significant reductions in systolic blood pressure (SBP), especially in individuals with higher baseline SBP levels (≥150 mm Hg), where reductions reached up to -20.8 mm Hg.

Reducing sodium intake alone also lowered SBP across all baseline levels, indicating that both dietary interventions are effective in managing blood pressure, with the most pronounced effects observed in those with higher initial blood pressure.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of Sodium Reduction and the DASH Diet in Relation to Baseline Blood Pressure. Juraschek, SP., Miller, ER., Weaver, CM., et al.[2022]

References

1. England pubmed.ncbi.nlm.nih.gov

Advice to reduce dietary salt for prevention of cardiovascular disease. [2018]

2. England pubmed.ncbi.nlm.nih.gov

Reduced dietary salt for prevention of cardiovascular disease. [2018]

3. England pubmed.ncbi.nlm.nih.gov

Reduced dietary salt for prevention of cardiovascular disease. [2020]

4. England pubmed.ncbi.nlm.nih.gov

Reduced dietary salt for prevention of cardiovascular disease. [2020]

5. United States pubmed.ncbi.nlm.nih.gov

Importance of the renin system in determining blood pressure fall with salt restriction in black and white hypertensives. [2022]

6. England pubmed.ncbi.nlm.nih.gov

Reducing dietary sodium and decreases in cardiovascular disease in Canada. [2021]

7. Italy pubmed.ncbi.nlm.nih.gov

Salt intake and hypertension therapy. [2013]

8. United States pubmed.ncbi.nlm.nih.gov

Low sodium diet after DASH: has the situation changed? Dietary Approaches to Stop Hypertension. [2019]

9. Switzerland pubmed.ncbi.nlm.nih.gov

The Effects of a Low Sodium Meal Plan on Blood Pressure in Older Adults: The SOTRUE Randomized Feasibility Trial. [2021]

10. England pubmed.ncbi.nlm.nih.gov

Salt and cardiovascular disease: insufficient evidence to recommend low sodium intake. [2021]

11. United States pubmed.ncbi.nlm.nih.gov

Effects of Sodium Reduction and the DASH Diet in Relation to Baseline Blood Pressure. [2022]