Salt is easy to overlook. It comes not only from the shaker but from packaged and restaurant foods, where sodium can add up across the day. A clinical trial published in 2023 offers a useful measure of how quickly that intake may matter: for most participants, blood pressure was lower during a week of low-sodium eating than during a week of high-sodium eating.
The study, published in JAMA, included 213 adults ages 50 to 75. Participants followed three eating patterns in a randomized order: their usual diet, a low-sodium diet and a high-sodium diet. Each pattern lasted one week. Researchers measured blood pressure and used urine tests to check sodium intake.
On average, systolic blood pressure—the top number—was about 8 millimeters of mercury lower during the low-sodium week than during the high-sodium week. It was about 6 points lower than during participants’ usual diets. About 73 percent had lower systolic pressure on the low-sodium plan than on the high-sodium one.
A fast response, with important limits
The result is notable because the change appeared within days, and the pattern held across participants with and without high blood pressure. But the study tested short-term responses, not whether the diet prevents heart attacks or strokes over years. It also does not mean every person will see the same change: individual responses varied.
Most importantly, the research diets were deliberately far apart in sodium. The low-sodium plan supplied about 500 milligrams a day, while the high-sodium plan supplied about 2,200 milligrams a day. Those were controlled study conditions, not a recommendation to aim for 500 milligrams. The researchers supplied meals and closely monitored participants; trying to reproduce the plan without medical guidance is not necessary to use the study’s broader lesson.
That lesson is that blood pressure can respond to sodium intake, even over a short period. It fits with public-health guidance to limit sodium. The U.S. Food and Drug Administration identifies 2,300 milligrams per day as the Daily Value for adults and children ages 14 and older. That is a ceiling for general guidance, not a personal target for every medical situation.
Where a practical change can start
For many people, the largest reductions may come from checking labels and choosing lower-sodium versions of foods they already buy. The FDA notes that most sodium in the typical U.S. diet comes from packaged and prepared foods, rather than salt added at the table. Comparing labels on bread, soups, sauces and ready-made meals can reveal differences that are hard to taste.
Small substitutions—such as rinsing canned beans, choosing unsalted nuts or making one meal at home—can help reduce intake without treating food as a medical intervention. Flavor can come from herbs, spices, citrus or vinegar. People who have been told to follow a specific diet, have kidney or heart conditions, or take blood-pressure medicines should ask their health-care professional before making a major change.
The trial does not replace blood-pressure treatment, and people should not change or stop prescribed medicines based on a dietary experiment. Instead, it adds a clear, practical finding to the evidence: for many adults, sodium is a modifiable part of blood pressure, and a thoughtful reduction may show up on the monitor sooner than expected.
