Replacing regular salt with a low-sodium alternative in household cooking and seasoning may be an inexpensive and simple way to reduce the risk of stroke, heart attack, and death from any cause in people with a history of stroke or high blood pressure, according to new research.
The innovative study explored the benefits of a potassium-containing salt substitute instead of traditional table salt in a key demographic, says Wesley Milks, MD, a cardiologist and an assistant professor of internal medicine at the Ohio State University Wexner Medical Center in Columbus, who was not involved in the new research. “There is a very strong association between uncontrolled high blood pressure and stroke. It has long been recognized that higher potassium intake and lower sodium intake are linked to blood pressure reduction, so this study appears to provide relatively strong confirmatory evidence of the association,” says Dr. Milks.
‘Clear Evidence’ That a Salt Substitute Can Improve Outcomes in Heart Disease
Although salt substitutes with reduced sodium and increased potassium levels have been shown to lower blood pressure, there is limited evidence connecting them with fewer heart attacks and strokes. To find out if the substitution actually resulted in fewer cardiovascular events and deaths, investigators recruited 20,995 participants from 600 villages in rural China, all of whom had either a previous stroke or were age 60 or older with poorly controlled blood pressure. The results were presented in a Hot Line session at the European Society of Cardiology (ESC) Congress 2021 and published in the New England Journal of Medicine on August 29.
Participants were cluster-randomized according to their village, with half the subjects using the provided salt substitute and the other half continuing to use regular salt. Those in the intervention group were told to use the substitution, composed of 75 percent sodium chloride and 25 percent potassium chloride, as a replacement for regular salt (100 percent sodium chloride) for all cooking, seasoning, and food preservation; they were also encouraged to reduce their use of the salt replacement compared with how much salt they usually consumed.
During an average follow-up of 4.74 years, more than 3,000 people had a stroke, more than 4,000 died, and more than 5,000 had a major cardiovascular event. The risk of fatal and nonfatal stroke was reduced with the salt substitute compared with regular salt, 29.14 versus 33.65 per 1,000 patient-years, a 14 percent risk reduction compared with normal salt use.
Major cardiovascular events were reduced with the salt substitute compared with the normal salt use group, 49.09 versus 56.29 per 1,000 patient-years, a risk reduction of 13 percent, as was the number of people who died from any cause, 39.27 versus 44.61 per 1,000 patient-years, a risk reduction of 12 percent.
This study provides clear positive evidence about this intervention, which could be taken up very quickly at very low cost, said the study's lead author, Bruce Neal, PhD, the executive director of the George Institute for Global Health in Sydney, in an ESC press release. “The trial result is particularly exciting because salt substitution is one of the few practical ways of achieving changes in the salt people eat,” said Dr. Neal.
These results confirm findings in a recent modeling study that projected that 365,000 strokes and 461,000 premature deaths could be avoided each year if salt substitute were used in China, he said, a reference to research published in April 2020 in the BMJ. “Salt substitution could be used by billions more with even greater benefits,” he said.
Reducing Blood Pressure by Reducing Salt Can Make a Significant Impact on Health
Why does sodium matter so much? It really comes down to blood pressure, says Jim Liu, MD, a cardiologist and an assistant professor in the division of cardiovascular medicine at the Ohio State University Wexner Medical Center in Columbus. Dr. Liu was not involved in the study.
Hypertension is one of the main risk factors for stroke and heart disease. If blood pressure is uncontrolled and remains high, the risk for stroke and heart disease will be elevated; a low sodium diet can help reduce blood pressure.
Americans Consume Too Much Sodium, Mostly From Processed and Fast Foods
Everyone needs sodium to maintain health, but too much is associated with high blood pressure. The average American consumes about 3,400 milligrams (mg) of sodium per day — nearly 50 percent more than the recommended amount of 2,300 mg per day, according to the U.S. Food and Drug Administration (FDA).
In the United States, most of that extra sodium doesn’t come from hitting the salt shaker too hard. Over 70 percent of our dietary sodium comes from packaged and prepared foods such as deli meat, pizza, tacos, and chips.
“I encourage patients to cook fresh to control the ingredients of their diet as much as possible, since many canned, frozen, or packaged foods contain much more sodium than is ideal for health,” says Milks.
Lowering Sodium Intake May Reduce the Need for Blood Pressure Medications
It can be challenging to reduce your intake to the recommended levels if you’ve been consuming a high amount of sodium, he says. “If I have patients who can't reach those daily goals, I would at least want them to reduce their current sodium intake by 1,000 mg per day. If using a salt substitute will help them achieve that, then that's definitely something I would encourage,” says Liu.
Patients who are able to reduce their sodium intake can substantially lower their blood pressure, he says. “This can sometimes result in deprescribing of blood-pressure-lowering medications,” says Liu.
In addition to lowering sodium intake, it's important to keep in mind the other lifestyle factors that can help with blood pressure, such as weight loss and exercise, he adds.
More Potassium in Your Diet Can Have Heart-Health Benefits
Potassium helps relieve tension in the blood vessel walls, which can also lower blood pressure, according to the American Heart Association (AHA).
The most natural way to for people to consume more potassium and less sodium is by consuming more natural sources of potassium — fruits and vegetables such as citrus fruits, bananas, tomatoes, spinach, and broccoli, says Milks.
Widespread Use of a Salt Substitute Could Help Address Health Inequities
The study authors pointed out that salt substitutes similar to the one used in their research have the potential to reduce health inequities related to cardiovascular disease.
Black adults are up to two times more likely to develop high blood pressure by age 55 compared with white adults, according to results from the CARDIA study, published in the Journal of the American Heart Association in July 2018.
Liu concurs, saying, “I think this can help with health disparities, since using a salt substitute is a relatively easy and inexpensive intervention. As the authors mentioned, the cost of salt substitutes is not very high, and it can be a practical intervention in low-income populations.”
A salt substitute also seems to be a change that people can stick with — the study population was able to keep using the salt substitute for five years, Liu adds.