Salt Substitutes Could Lower Blood Pressure, Yet Few Americans Use Them

Between 2017 and 2020, 122.4 million American adults, or 46.7 percent, had high blood pressure, and the condition contributed to more than 130,000 deaths. Too much sodium and too little potassium in the diet are both risk factors. A cheap product that swaps some or all of the sodium in table salt for potassium can help address both. Yet a new analysis finds that almost no one is using it.

The study, led by Yinying Wei, a Ph.D. candidate in applied clinical research and in the hypertension section of the cardiology division at UT Southwestern Medical Center in Dallas, is the first to track long-term trends in salt substitute use among a nationally representative sample of U.S. adults. It draws on the National Health and Nutrition Examination Survey, known as NHANES, from 2003 to 2020, and covers 37,080 adults aged 18 and older. Among them, 37.9 percent were 18 to 39, 36.9 percent were 40 to 59, and 25.2 percent were 60 or older. Women made up 50.6 percent of the group, and 10.7 percent identified as non-Hispanic Black.

Use peaked at 5.4 percent of all adults in 2013-2014, then fell to 2.5 percent by 2017 through March 2020, when data collection stopped because of the pandemic. Researchers also looked at adults eligible to use substitutes, meaning those with healthy kidney function who were not taking medications or supplements that affect blood potassium. Only 2.3 to 5.1 percent of them did so.

The pattern held across blood pressure categories. Use was highest, at 3.6 to 10.5 percent, among people with high blood pressure controlled by medication. It ranged from 3.7 to 7.4 percent among those whose pressure remained uncontrolled despite treatment. For people with untreated high blood pressure and those with normal readings, use stayed below 5.6 percent. High blood pressure was defined as 130/80 mm Hg or above. Adults who ate at restaurants three or more times a week appeared less likely to use substitutes, but the difference lost statistical significance after adjusting for age, race and ethnicity, education and insurance status.

"Even among individuals with treated and poorly managed or untreated high blood pressure, most continued to use regular salt," Wei said. She urged health care professionals to raise the subject with patients whose blood pressure is persistent or hard to manage.

The caution attached to these products is real. Potassium-based substitutes can push blood potassium to dangerous levels in people with kidney disease or those taking certain medications or potassium supplements, and excess potassium can cause irregular heart rhythms. People with high blood pressure who are considering a switch should consult a clinician first. The American Heart Association recommends no more than 2,300 mg of sodium a day, with an ideal limit below 1,500 mg for most adults, particularly those with hypertension. Cutting 1,000 mg a day can improve blood pressure for most people. Most dietary sodium comes from processed and packaged foods and restaurant meals, not the salt shaker. Potassium salt tastes much like ordinary salt, though it can leave a bitter aftertaste when heated.

Amit Khera, an American Heart Association volunteer expert who was not involved in the study, called it an important and easily missed opportunity. He is a professor of medicine and director of preventive cardiology at UT Southwestern. He said it was eye-opening that use remains so low and has not improved in two decades, and that the finding should prompt patients and clinicians to discuss substitutes, especially in visits focused on high blood pressure.

The study has limits. Use was self-reported, so it may be under-reported or misclassified. All salt substitute types were grouped together, so potassium-enriched salt could not be separated from other alternatives. The survey also did not record how much was used. Wei said future work should examine why use is so low, looking at taste acceptance, cost, and limited awareness among patients and clinicians.