The finding stems from a study of 213 adults, 50 to 75 years old, including people whose blood pressure was considered normal, as well as those with high blood pressure (hypertension), either treated or untreated.

Researchers recorded the participants’ blood pressure after they had adhered, for one week, to a low-sodium diet — meals, snacks and beverages that included about one teaspoon less of table salt (2.3 grams of sodium) than their usual diet. That was compared with the participants’ blood pressure after they had consumed a high-sodium diet for a week. For nearly three-fourths of the participants, blood pressure was lower with the low-sodium diet.

That diet resulted in, on average, a systolic blood pressure that was 8 mmHg (millimeters of mercury, the standard of measurement for blood pressure) lower than the systolic pressure recorded after a high-sodium diet, and 6 mmHg lower than after their usual diet.

Systolic blood pressure — the top (or first) number in a blood pressure reading — represents the force produced by the heart when it beats, pushing blood through the arteries. The researchers wrote that their findings indicate that “clinically meaningful lowering of [blood pressure] through dietary sodium reduction can be achieved safely and rapidly within 1 week.”

Having high blood pressure increases a person’s risk for heart disease, heart attack or stroke but also raises the likelihood of developing a range of health problems, including kidney disease, visual problems, sexual dysfunction and peripheral artery disease. Nearly half of U.S. adults — about 120 million people — have hypertension or are taking medication for it, according to the Centers for Disease Control and Prevention.