Cutting Down on Salt Lowers Blood Pressure, Even for Those Already on Medication
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Most people can significantly lower their blood pressure, even if they are already on blood pressure medication, if they cut down on salt by about a teaspoon a day, according to new findings published November 11 in JAMA and presented at the American Heart Association Scientific Sessions 2023 in Philadelphia.
The study, one of the largest to look at the effects of reducing sodium on blood pressure, found that nearly 3 in 4 people saw a decline in their blood pressure in as little as one week when they went from a high salt to low salt diet, says Norrina Allen, PhD, a coauthor of the study, a professor of preventive medicine, and the director of the Institute for Public Health and Medicine at Northwestern Medicine in Chicago.
“The average amount of blood pressure lowering was about 8 millimeters of mercury (mmHg) for systolic blood pressure, which is similar to the effect produced by medications for high blood pressure,” says Dr. Allen.
Only 1 in 4 U.S. Adults With High Blood Pressure Have It Under Control
High blood pressure is a major risk factor for heart attack and stroke and a leading cause of premature death around the world. Nearly half of adults in the United States — or nearly 120 million people — have high blood pressure (also called hypertension), according to the Centers for Disease Control and Prevention (CDC).
Many people have blood pressure that can be difficult to control, even those taking medications, says Allen. Only about 1 in 4 adults with hypertension have it under control, per the CDC.
Although a low-sodium, heart-healthy diet is recommended for people with high blood pressure, there hasn’t been much recent research to quantify the benefits, and those studies have often excluded people on blood-pressure-controlling medications, according to the authors.
The Effects of a Diet With High Sodium vs. Almost No Sodium
The study included 213 participants between the ages of 56 and 65 years old. Sixty-four percent were female; the same percentage of participants were Black; 33 percent were white; and 1 percent were from other races or did not identify their race.
Participants were randomly placed in one of two groups: one that ate a high-sodium diet of 2,200 milligrams (mg) per day on top of their usual diet; the other, a low-sodium diet of 500 mg in total per day, which they followed for one week. The American Heart Association recommends sodium intake be under 1,500 mg per day. The next week, the two groups crossed over and followed the opposite diet.
On the day before each study visit, participants wore blood pressure monitors and collected their urine over 24 hours.
The investigators found that:
- Systolic blood pressure was significantly lowered, by 7 to 8 mmHg, in participants who ate the low-sodium diet compared with those on the high-sodium diet, and by 6 mm/Hg compared with their usual diet.
- Overall, 72 percent of participants lowered their systolic blood pressure on the low-sodium diet compared with their usual diet.
- The effect of reducing sodium on blood pressure was consistent in people with normal blood pressure, treated high blood pressure, and untreated high blood pressure.
“These results indicate that lowering blood pressure through dietary sodium reduction can be achieved safely and rapidly within one week,” said the study lead author, Deepak K. Gupta, MD, an associate professor of medicine and the director of the Vanderbilt Translational and Clinical Cardiovascular Research Center at Vanderbilt University Medical Center in Nashville, Tennessee, in a press release.
RELATED: 10 Sneaky Sodium Bombs
The findings here confirm what we know from prior studies: A low-sodium diet lowers blood pressure, says Luke Laffin, MD, a cardiologist and the codirector of the center for blood pressure disorders at Cleveland Clinic. “This study shows us that this amount of lowering doesn’t change much, [whether or not] a patient has a diagnosis of hypertension, or what medication (or medications) the patient is taking for their blood pressure,” says Dr. Laffin, who was not involved in the study.
Participants Ate Almost Double the Recommended Amount of Sodium
The usual diet for most people in the study was already very high in sodium, around 4,500 mg per day. The average American consumes about 3,400 mg per day — nearly double the recommended amount of 2,300 mg per day, according to the U.S. Food and Drug Administration (FDA).
Most of that extra sodium doesn’t come from the salt shaker. Instead, over 70 percent of our dietary sodium comes from packaged and prepared foods like deli meat, pizza, tacos, and chips.
To Control High Blood Pressure, Changes in Both Diet and Medications Are Often Needed
This evidence reinforces the importance of reductions in dietary sodium intake to help control blood pressure, even in people already taking medications for hypertension, said Gupta. “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,” he added.
People with high blood pressure shouldn’t see blood pressure lowering medication and lifestyle changes as an either/or proposition, says Laffin. “Most people need a combination, with a low sodium diet being a cornerstone of lifestyle modification.”
When it comes to preventing or treating chronic diseases that contribute to the development of heart disease — including hypertension, diabetes, high cholesterol, and obesity — it should never be one or the other, he says.
“Lifestyle modification should be a given and the ‘base of the pyramid,’ so to speak. If goals are not reached with lifestyle, then we add medications. I hope this study re-emphasizes this to the population. Unfortunately, many physicians don’t have enough time to discuss both medications and lifestyle with patients, so patients are left to think it’s one or the other, either lifestyle or medications,” says Laffin.
Expert Tips on Lowering Sodium Intake
A low-sodium diet is the number-one lifestyle change that Dr. Laffin focuses on when first meeting a person with high blood pressure. “This study illustrates why I do this. Patients see blood pressure lowering within a day or two. The same is not true of things like exercise or weight loss; they take time,” he says.
Adopting a low-sodium diet is easy to do in the short term, but sustaining it long-term — as is true for many dietary pattern changes — is more difficult, says Laffin.
People should start with simply quantifying how much sodium they eat by reading labels and doing online research, he suggests.
Dr. Allen recommends looking for low- or lower-sodium versions of the foods you eat, and when comparing foods, look on the labels for the sodium content.
As a goal, Laffin suggests aiming for less than 2,300 mg daily (equivalent to one level teaspoon) and to ideally consume less than 1,500 mg daily.
But beware: Hidden sodium is everywhere, he says. “Bread, salad dressings, and cheese are foods we don’t think of as having a lot of salt, but that actually do.”
Focusing on a plant-based diet rich in fresh fruits and vegetables (and avoiding highly processed foods) is another way to reduce the amount of sodium in your diet, says Allen.
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