500 Participants Needed

High vs Low Salt Diet for High Blood Pressure

Recruiting at 1 trial location
DG
CR
Overseen ByCassandra Reynolds, BS
No Placebo GroupAll trial participants will receive the active study treatment (no placebo)

Trial Summary

What is the purpose of this trial?

This trial will have participants follow different salt diets to see how their blood pressure changes. It focuses on middle-aged people from a previous study. Researchers believe that salt intake affects blood pressure through inflammation and want to understand this better.

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.

What data supports the effectiveness of the treatment High Salt Diet, Low Salt Diet for high blood pressure?

Research shows that reducing salt intake can lower blood pressure in people with high blood pressure. For example, one study found that switching from a high salt diet to a low salt diet reduced blood pressure by 17/6 mm Hg in white patients and 22/10 mm Hg in black patients.12345

Is a low or high salt diet generally safe for humans?

Reducing salt intake is generally safe for most people and can help lower blood pressure, especially in older adults, African Americans, and those who are overweight. High salt intake can increase the risk of high blood pressure and related health issues, but reducing salt intake usually has minimal adverse effects unless done excessively.678910

How does the High vs Low Salt Diet treatment for high blood pressure differ from other treatments?

This treatment is unique because it directly compares the effects of high and low salt diets on blood pressure, whereas most existing treatments focus on reducing salt intake without exploring the potential effects of a high salt diet. Additionally, the research highlights that an excessively low salt diet might harm the heart, which is not commonly addressed in standard dietary recommendations for high blood pressure.3451112

Eligibility Criteria

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.
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Timeline

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

Treatment Details

Interventions

  • High Salt Diet
  • Low Salt Diet
Trial OverviewThe 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.
Participant Groups
2Treatment groups
Experimental Treatment
Group I: Low Salt Diet then High Salt DietExperimental Treatment2 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 DietExperimental Treatment2 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).

Find a Clinic Near You

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+

Findings from Research

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

References

Importance of the renin system in determining blood pressure fall with salt restriction in black and white hypertensives. [2022]
Sodium restriction in hypertension. [2007]
Reduced dietary salt for prevention of cardiovascular disease. [2018]
Reduced dietary salt for prevention of cardiovascular disease. [2020]
Advice to reduce dietary salt for prevention of cardiovascular disease. [2018]
Salt intake and hypertension therapy. [2013]
Salt and hypertension: is salt dietary reduction worth the effort? [2022]
The Effects of a Low Sodium Meal Plan on Blood Pressure in Older Adults: The SOTRUE Randomized Feasibility Trial. [2021]
Reducing salt intake for prevention of cardiovascular disease--times are changing. [2015]
10.United Statespubmed.ncbi.nlm.nih.gov
Salt sensitivity, a determinant of blood pressure, cardiovascular disease and survival. [2022]
11.United Statespubmed.ncbi.nlm.nih.gov
Effects of Sodium Reduction and the DASH Diet in Relation to Baseline Blood Pressure. [2022]
12.United Statespubmed.ncbi.nlm.nih.gov
Excessively low salt diet damages the heart through activation of cardiac (pro) renin receptor, renin-angiotensin-aldosterone, and sympatho-adrenal systems in spontaneously hypertensive rats. [2022]