High vs Low Salt Diet for High Blood Pressure

No longer recruiting at 1 trial location

Overseen By Cassandra Reynolds, BS

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Vanderbilt University Medical Center

Must not be taking: Steroids, NSAIDS, Anti-inflammatories

Disqualifiers: Resistant hypertension, Heart failure, Rheumatologic conditions, Immune deficiency, Others

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

Compensation: Varies

Number of Visits: 2

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to understand how varying salt levels in the diet affect blood pressure and the body's immune response. Participants will alternate between a low-salt diet and a high-salt diet to observe changes in blood pressure. The goal is to gain insights into salt sensitivity, which can impact heart health. The trial seeks individuals with high blood pressure, whether untreated or managed with up to three medications, who are willing to adhere to the diet plan. As an unphased study, this trial provides a unique opportunity to contribute to significant research on diet and heart health.

Will I have to stop taking my current medications?

The trial does not specify if you need to stop taking your current medications, but it includes people who are not on blood pressure medications or those with controlled blood pressure using up to 3 medications. If you are taking 4 or more blood pressure medications, you would not be eligible.

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

Research has shown that consuming a lot of salt can raise blood pressure. Studies have linked excessive salt intake to a higher risk of heart problems and even death. High salt consumption can also prevent blood pressure from dropping at night, which negatively affects heart health.

Conversely, reducing salt intake can help lower blood pressure for many people. Research indicates that cutting down on salt can decrease blood pressure and is safer for those with hypertension. In one study, most participants experienced a drop in blood pressure when they reduced their salt intake. Reducing salt led to a more noticeable decrease in blood pressure compared to those who maintained their salt consumption.

Overall, a high-salt diet poses known risks, particularly for heart health, while a low-salt diet is generally considered safe and can help lower blood pressure. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it directly tests how different salt intake levels affect high blood pressure. Most traditional treatments for high blood pressure involve medications like ACE inhibitors, beta-blockers, or lifestyle changes such as exercise and weight loss. This study, however, focuses on dietary changes — specifically, adjusting salt intake — which could offer a simple, non-drug approach to managing blood pressure. The trial's unique approach of comparing high and low salt diets could reveal how significantly dietary sodium impacts blood pressure, potentially leading to new dietary recommendations for those with hypertension.

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

This trial will compare the effects of a high-salt diet and a low-salt diet on blood pressure. Research has shown that excessive salt intake can raise blood pressure. Studies have found that reducing salt can lower blood pressure in individuals with and without hypertension. Specifically, switching from a high-salt diet to a low-salt diet can reduce blood pressure by about 8 mmHg, a significant decrease. High-salt diets increase blood pressure by affecting sodium handling and blood vessel health. Overall, reducing salt intake consistently helps manage and lower blood pressure effectively. ^{2 6 7 8 9}

Are You a Good Fit for This Trial?

This trial is for adults who have normal blood pressure or high blood pressure that's either untreated or controlled with up to three medications. Participants must not be on certain drugs like steroids, avoid anti-inflammatory meds, and can't have conditions like heart failure or severe allergies to food.

Inclusion Criteria

Potentially eligible individuals must consent to and be willing to adhere to the study protocol.

I am not on anti-HTN meds or I control my high blood pressure with up to 3 meds.

Exclusion Criteria

I am taking medication to manage my blood pressure.

I take 4 or more blood pressure medications, including a diuretic, but my blood pressure is still high.

Medical contraindications to foods, e.g. celiac disease, nut allergy, egg allergy, etc.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Low Salt Diet

Participants follow a low-salt diet for 7 days with meals prepared in the Metabolic Kitchen

1 week

1 visit (in-person) for diet provision

High Salt Diet

Participants follow a high-salt diet for 7 days with supplementation of Na+ bullion packets

1 week

1 visit (in-person) for diet provision

Follow-up

Participants are monitored for immune response and blood pressure changes after dietary interventions

2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• High Salt Diet
• Low Salt Diet

Trial Overview

The CARDIA-Salt Sensitivity of Blood Pressure study tests how a person's blood pressure changes when they switch between diets with different salt levels. It aims to understand the body's inflammatory response to salt and its effect on blood pressure in middle-aged individuals.

How Is the Trial Designed?

Group I: Low Salt Diet then High Salt Diet Experimental Treatment 2 Interventions

The low-salt diet is comprised of 7 days of freshly prepared frozen meals, snacks, and Na+ free water. All low-salt meals will be prepared in each site's Metabolic Kitchen, with standardization of diets across sites. The low-salt diet includes: 20 mEq Na+ (±2 mEq) (460 mg/day), 100 mEq potassium (±2 mEq), and 1,000 mg calcium (±50 mg). The high-salt diet will be achieved through the supplementation of each participant's usual diet with Na+ bullion packets (2 packets per day). This will increase Na+ intake by approximately 2,200 mg (≈100 mEq Na+) to a total greater than 5,000 mg Na+ per day based on prior estimates of Na+ intake (see section C1.2). In addition, 1,000 mg of calcium carbonate (provided via Tums tablets) will be taken daily on the high Na+ diet to reduce the potential impact of changes in calcium intake on blood pressure.

Group II: High Salt Diet then Low Salt Diet Experimental Treatment 2 Interventions

The high-salt diet will be achieved through the supplementation of each participant's usual diet with Na+ bullion packets (2 packets per day). This will increase Na+ intake by approximately 2,200 mg (≈100 mEq Na+) to a total greater than 5,000 mg Na+ per day based on prior estimates of Na+ intake (see section C1.2). In addition, 1,000 mg of calcium carbonate (provided via Tums tablets) will be taken daily on the high Na+ diet to reduce the potential impact of changes in calcium intake on blood pressure. The low-salt diet is comprised of 7 days of freshly prepared frozen meals, snacks, and Na+ free water. All low-salt meals will be prepared in each site's Metabolic Kitchen, with standardization of diets across sites. The low-salt diet includes: 20 mEq Na+ (±2 mEq) (460 mg/day), 100 mEq potassium (±2 mEq), and 1,000 mg calcium (±50 mg).

Who Is Running the Clinical Trial?

Vanderbilt University Medical Center

Lead Sponsor

Trials

922

Recruited

939,000+

Northwestern University

Collaborator

Trials

1,674

Recruited

989,000+

University of Alabama at Birmingham

Collaborator

Trials

1,677

Recruited

2,458,000+

Published Research Related to This Trial

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

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

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]

Hypertensive patients, whether treated or untreated, can significantly benefit from reducing sodium intake, leading to lower blood pressure and potentially requiring fewer medications.

Implementing a behavior modification program can effectively help patients change their eating habits, and monitoring blood pressure and urinary sodium levels can track adherence to the dietary changes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Sodium restriction in hypertension. Langford, HG., Schlundt, D., Levine, K.[2007]

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]

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

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

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]

Citations

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Nutrition and Hypertension Researches in 2023

The results indicated that reducing dietary sodium significantly lowered BP, regardless of hypertension status or antihypertensive medication ...

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Blood Pressure Effects of Sodium Reduction | Circulation

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An estimated 1.89 million deaths each year are associated with consuming too much sodium, causing raised blood pressure and increased risk of ...

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ahajournals.org

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Excess salt intake leads to elevation in blood pressure which drives cardiovascular morbidity and mortality.

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Sodium reduction

An estimated 1.89 million deaths each year are associated with consuming too much sodium, a well-established cause of raised blood pressure and ...