CHICAGO — Reducing salt can lower blood pressure in three out of four individuals, a new study reveals. Scientists have found that this effect also extends to patients who are already taking blood pressure-lowering drugs. By simply not adding salt to their food, these patients can achieve further reductions in their blood pressure.
The study revealed that a reduction of just one teaspoon of salt per day can lead to a decrease in systolic blood pressure. This decrease is comparable to what is typically achieved through medication. This research, a collaborative effort by Northwestern Medicine, Vanderbilt University Medical Center, and the University of Alabama, is groundbreaking. It is the first to demonstrate that individuals already on medication for high blood pressure can further lower their readings by reducing their salt intake.
“In the study, middle-aged to elderly participants reduced their salt intake by about one teaspoon a day compared with their usual diet. The result was a decline in systolic blood pressure by about six millimeters of mercury (mm Hg), which is comparable to the effect produced by a commonly utilized first-line medication for high blood pressure,” says Deepak Gupta, MD, an associate professor of medicine at Vanderbilt University Medical Center and co-principal investigator, in a media release.
“We found that 70-75 percent of all people, regardless of whether they are already on blood pressure medications or not, are likely to see a reduction in their blood pressure if they lower the sodium in their diet,” adds co-principal investigator Norrina Allen, PhD, the Quentin D. Young Professor of Health Policy in the Department of Preventive Medicine and co-principal investigator of the study.
This study ranks among the largest to explore the impact of salt reduction in the diet on blood pressure. It uniquely included individuals with high blood pressure, also known as hypertension, who were already on medication.
“We previously didn’t know if people already on blood pressure medication could actually lower their blood pressure more by reducing their sodium,” says Allen.
The American Heart Association (AHA) recommends a daily sodium intake of less than 1,500 milligrams, and this study aimed to reduce sodium intake even more significantly.
“It can be challenging but reducing your sodium in any amount will be beneficial,” Allen continues. “High blood pressure can lead to heart failure, heart attacks and strokes, because it puts extra pressure on your arteries. It affects the heart’s ability to work effectively and pump blood.”
The study involved participants in their 50s, 60s, and 70s from Birmingham, Alabama, and Chicago. They were assigned either a high-sodium diet (an additional 2,200 mg per day) or a low-sodium diet (a total of 500 mg per day) for one week. After this period, they switched to an alternate diet for another week. On the day before each study visit, participants wore blood pressure monitors and collected their urine for 24 hours.
The results were significant. Among the 213 participants, systolic blood pressure was notably reduced by seven to eight mm Hg on the low-sodium diet compared to the high-sodium diet, and by six mm Hg compared to their usual diet. Overall, 72 percent of the participants experienced a reduction in their systolic blood pressure when following the low-sodium diet compared to their usual diet.
“The effect of reduction in dietary sodium on blood pressure lowering was consistent across nearly all individuals, including those with normal blood pressure, high blood pressure, treated blood pressure and untreated blood pressure,” Gupta reports.
“Just as any physical activity is better than none for most people, any sodium reduction from the current usual diet is likely better than none for most people with regards to blood pressure.”
“This reinforces the importance of reduction in dietary sodium intake to help control blood pressure even among individuals taking medications for hypertension,” Allen notes.
The blood pressure-lowering effect of dietary salt reduction was achieved rapidly and safely within one week, according to the research team.
“The fact that blood pressure dropped so significantly in just one week and was well tolerated is important and emphasizes the potential public health impact of dietary sodium reduction in the population, given that high blood pressure is such a huge health issue worldwide,” concludes co-investigator Cora Lewis, MD, professor and chair of the Department of Epidemiology and professor of Medicine at the University of Alabama at Birmingham.
“It is particularly exciting that the products we used in the low-sodium diet are generally available, so people have a real shot at improving their health by modifying their diet in this way.”
The findings, published in the Journal of the American Medical Association, were presented at the annual AHA Scientific Sessions in Philadelphia.
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South West News Service writer Stephen Beech contributed to this report.