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

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores how varying salt levels in diets affect blood pressure and overall health, with a focus on why some individuals are more sensitive to salt. Participants will follow both a high sodium diet (high salt diet) and a low sodium diet (low salt diet) to observe the effects on blood pressure and kidney function. The goal is to better understand salt-sensitive hypertension and develop new diagnostic and treatment methods. Ideal candidates for this study speak English and have slightly elevated blood pressure, without major health issues like kidney disease or diabetes. As an unphased trial, this study offers a unique opportunity to contribute to groundbreaking research on salt sensitivity and hypertension.

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.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research shows that a low-sodium diet is generally safe and easy to follow. Studies have found that eating less salt can lower blood pressure, which benefits heart health. For example, a large study found that reducing salt can significantly lower blood pressure, especially in people with high blood pressure.

Conversely, consuming too much salt can be concerning. Research indicates that a high-sodium diet can raise blood pressure and may cause non-dipping, where blood pressure remains high even at night, increasing heart risks. Some people with high blood pressure may notice a significant increase when they consume more salt.

Both low and high sodium diets have been studied for their effects on blood pressure and are generally safe for short periods. However, it's important to consider personal health before making significant dietary changes. Always consult a healthcare provider, especially if existing health conditions are present. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it investigates the impact of dietary sodium levels on high blood pressure, offering insights that could reshape current dietary recommendations. Unlike standard treatments like medications that target blood pressure directly, this trial explores how adjusting sodium intake alone—either lowering it to 1,200 mg/day or raising it to 4,200 mg/day—can influence blood pressure. This approach is unique because it focuses on a non-pharmacological intervention, potentially reducing reliance on medication and highlighting the power of diet in managing hypertension. Understanding these effects could lead to more personalized dietary guidelines, providing a simple yet effective tool for blood pressure management.

What evidence suggests that this trial's treatments could be effective for high blood pressure?

This trial will compare the effects of a low sodium diet with a high sodium diet on blood pressure. Research has shown that reducing salt intake can lower blood pressure in individuals with hypertension. In one study, reducing salt led to an average drop of 8 points in the systolic blood pressure, compared to a high-salt diet. Another study found a similar decrease of 6.7 points with significant salt reduction. Conversely, high salt consumption is linked to increased blood pressure, raising the risk of heart issues. The INTERSALT Study found that adding 2300 mg of salt daily could raise systolic blood pressure by about 3.5 points. These findings suggest that reducing salt is an important strategy for managing blood pressure. ^{3 6 7 8 9}

Who Is on the Research Team?

Srividya Kidambi, MD

Principal Investigator

Medical College of Wisconsin

Are You a Good Fit for This Trial?

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 for a Trial Participant

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

What Are the Treatments Tested in This Trial?

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.

How Is the Trial Designed?

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+

Published Research Related to This Trial

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]

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]

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]

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]

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]

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, SM., et al.[2020]

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]

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]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC6770596/

Sodium Intake and Hypertension - PMC - PubMed Central - NIH Prolonged modest reduction in salt intake induces a relevant fall in blood pressure in both hypertensive and normotensive individuals, irrespective of sex and ...

2. escardio.org escardio.org/Journals/E-Journal-of-Cardiology-Practice/Volume-22/salt-and-hypertension-current-views

Salt and hypertension: current views The association between sodium consumption and hypertension is well known, as high sodium intake can negatively affect control of hypertension.

3. who.int who.int/news-room/fact-sheets/detail/sodium-reduction

Sodium reduction The primary health effect associated with diets high in sodium is raised blood pressure which increases the risk of cardiovascular diseases, ...

4. nature.com nature.com/articles/s41371-025-00990-1

The Growing Global Benefits of Limiting Salt Intake: an ... The INTERSALT Study investigators estimated a 2300 mg increase in daily sodium intake was associated with ~3.5 mmHg higher systolic BP (SBP) [1] ...

5. ahajournals.org ahajournals.org/doi/10.1161/HYPERTENSIONAHA.123.20544

Dietary Sodium Reduction Is Best for Reducing Blood ... The largest reduction in systolic BP, −6.7 mm Hg, was observed when sodium intake was lowered from high (150 mmol/day) to low (<50 mmol/day) ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10350516/

Effects of a high salt diet on blood pressure dipping and the ... In conclusion, the evidence suggests that a high salt diet is associated with a blunted, non-dipping, or reverse dipping blood pressure pattern, ...

7. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC5098396/

Dietary Sodium and Health: More Than Just Blood Pressure Sodium is essential for cellular homeostasis and physiological function. Excess dietary sodium has been linked to elevations in blood pressure (BP).

8. sciencedirect.com sciencedirect.com/science/article/pii/S1470211824042659

The health impacts of dietary sodium and a low-salt diet High salt intake is likely to contribute to cardiovascular risk primarily through its effects on blood pressure, as well as through blood pressure independent ...

9. ama-assn.org ama-assn.org/public-health/prevention-wellness/what-doctors-wish-patients-knew-about-sodium-consumption

What doctors wish patients knew about sodium consumption “With about half of the people with high blood pressure, increasing the sodium intake significantly raises blood pressure,” said Dr. Egan.