- The average diets of middle-aged and older adults in the United States include excessive salt, which experts believe has contributed to increased mortality over the last decade.
- In a recent study of 213 people, a low sodium diet reduced blood pressure in nearly 3 out of 4 people compared to a high sodium diet.
- The decline in blood pressure researchers observed was independent of hypertension status and blood pressure medication use.
- The low sodium diet’s anti-hypertensive effect was comparable with a widely used blood pressure medication.
High-salt diets are commonly associated with increases in blood pressure and risk of cardiovascular mortality, even among individuals with healthy blood pressure.
Cardiologist Dr. Bradley Serwer, chief medical officer at cardiovascular and anesthesiology services provider VitalSolution, told Medical News Today: “For the general population, it is recommended to have a sodium intake of under 2300mg per day. For those with high blood pressure or heart disease, we recommend less than 1500mg per day. […]To put this in perspective, a tablespoon of salt has approximately 2,300mg of sodium.”
However, dietary sodium recommendations have been disputed, in part due to varying blood pressure responses to sodium consumption. The blood pressure effect of dietary sodium among people taking blood pressure medications has not been studied well to date, either.
A novel study sponsored by Vanderbilt University Medical Center found that a low sodium diet can reduce blood pressure as much as a prescription drug.
Researchers with Northwestern University and the University of Alabama at Birmingham collaborated on this work.
“Collectively, these data may inform recommendations to patients; namely, clinically meaningful lowering of blood pressure through dietary sodium reduction can be achieved safely and rapidly within [one] week; an effect comparable with that of a common first-line antihypertensive medication,” the study’s authors said:
These findings appear in
Salt sensitivity of blood pressure (SSBP) refers to changes in blood pressure associated with changes in salt intake.
Blood pressure naturally fluctuates to maintain sodium balance. Susceptibility to SSBP may lie in sodium imbalances and abnormalities of hormones regulating sodium retention and excretion.
Vascular dysregulation may be responsible as well, but exactly how sodium influences blood pressure is yet to be understood.
Medical News Today discussed this study with Michelle Routhenstein, preventative cardiology dietitian at EntirelyNourished.com, who was not involved in the research.
How salt consumption affects blood pressure
“Consuming too much salt can increase blood pressure by negatively impacting the kidney’s ability to regulate fluids, and by negatively impacting the blood vessel lining, leading them to constrict and cause high blood pressure. When blood pressure is high for a prolonged period of time it can lead to kidney damage, heart damage and increase the risk of cardiovascular events.”
— Michelle Routhenstein
Preliminary research suggests that excess dietary sodium consumption may cause inflammation, which can trigger high blood pressure.
“Dietary restriction is always first-line therapy in addressing high blood pressure. If someone is unable to achieve normal blood pressure with a low sodium diet, then we start medications,” Dr. Serwer explained.
The CARDIA study
The Coronary Artery Risk Development in Young Adults (CARDIA) study, which began in 1985, was chosen to explore the mechanisms behind SSBP.
Researchers considered this community-based study “to investigate the immune response to dietary salt loading” among middle-aged and older people.
CARDIA utilized standardized low- and high-salt diets and 24-hour ambulatory blood pressure monitoring, which no other known U.S.-based inquiry had attempted.
The collaborators hoped to discover “a more readily available approach” for determining salt sensitivity or resistance.
The present study aimed “to examine the distribution of within-individual blood pressure response to dietary sodium, the difference in blood pressure between individuals allocated to consume a high- or low-sodium diet first, and whether these varied according to baseline blood pressure and antihypertensive medication use.”
The Coronary Artery Risk Development in Young Adults (CARDIA)–SSBP study recruited 213 community-based individuals between April 2021 and February 2023. The participants were 50 to 75 years of age.
Out of a total of 213 participants, 25% had typical blood pressure (normotension), 20% had controlled hypertension, 31% had uncontrolled hypertension, and 25% had untreated hypertension.
Among the participants completing both diets, the average age was 61 years. Females made up 65% of the group, and 64% were Black.
People with resistant hypertension or contraindications to high or low sodium diets were excluded.
The participants were randomized into two groups. The groups either followed a high sodium diet, adding 2,200 mg to their usual diet for one week, or a low sodium diet, adding 500 mg of sodium for one week. Then, they switched diets for one week afterward.
The one-week low sodium diet resulted in a reduction in systolic blood pressure, mirroring the average effect of 12.5 mg of hydrochlorothiazide, a prescription hypertension drug.
Overall, 71.7% of all individuals saw a reduction on their blood pressure with a low salt diet. Dr. Norrina Allen, Ph.D., of Northwestern University Feinberg School of Medicine, told MNT that “This effect was consistent regardless of whether a person was on an antihypertensive medication or not.“
Only 8% of the study participants reported any mild adverse events following this regimen, compared to 9.9% of those consuming the high sodium diet.
Moreover, the individual and between-group changes were not contingent on hypertension status or blood pressure medication use. The blood pressure declines were consistent across sub-groups as well.
The study’s authors believe that their approach of adding dietary sodium above everyone’s regular diet reflected realistic fluctuations in sodium intake. It went further than the DASH-Sodium and GenSalt studies’ diets, which did not exceed the sodium consumption of usual diets.
“One of the strengths of the study that stands out is their use of a 24-hour urine sodium excretion, a gold standard method of evaluating sodium intake in population surveys. The study also included a wider variety of individuals to assess the effect of dietary sodium effect on their blood pressure—from individuals with normal blood pressure to those with high blood pressure, treated or untreated, managed or not managed appropriately,” Routhenstein said.
However, the diets could not be fully controlled, so the researchers could not discount potential nonsodium dietary factors.
Fortunately, modifying salt intake can be quite easy. As Dr. Allen said: “The low salt diet was made up of foods available at regular grocery stores.”
“I strongly recommend reading food and beverage labels. Many patients are unaware of the sodium content of certain foods and drinks. Canned vegetables, highly processed meals, fast food, and even [food in] fine dining restaurants are often very high in sodium,” Dr. Serwer cautioned.
The cardiologist encouraged everyone to prepare food at home whenever possible, where they can control the amount of ingredients.
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