Study details and key findings

According to CDC, 120 million people, or almost half of U.S. adults, either have hypertension or are taking medication for it. Hypertension can increase the risk of several health conditions, including heart disease, heart attack, stroke, kidney disease, and more.

In the study, researchers evaluated 213 participants ages 50 to 75 years old. The median age of participants was 61 years, 65% were female, and 64% were Black. Among the participants, 25% had normal blood pressure, 20% had controlled hypertension, 31% had uncontrolled hypertension, and 25% had untreated hypertension.

Participants first attended a baseline visit while consuming their normal diet. After that, they ate a high- or low-sodium diet for one week before switching to the opposite diet. Researchers recorded participants' blood pressure after each week.

During the high-sodium week, participants ate their normal diet as well as two bouillon packets, which each contained 1,100 milligrams of sodium. In comparison, during the low-sodium week, participants worked with dietitians to limit their sodium consumption to 500 milligrams a day. Participants' sodium consumption during this week was reduced by around one teaspoon of salt (2,300 milligrams of sodium) a day.

Overall, the researchers found that participants had lower blood pressure after eating a low-sodium diet for a week compared to after a week of a high-sodium diet. On average, the participants' blood pressure was 8 mmHg lower after than low-sodium diet compared to the high-sodium diet and 6 mmHg lower than after their normal diet.

According to the researchers, the results suggest that "clinically meaningful lowering of [blood pressure] through dietary sodium reduction can be achieved safely and rapidly within 1 week."

Norrina Allen, professor of preventive medicine at Northwestern University's Feinberg School of Medicine, noted that the reduction in blood pressure participants experienced on the low-sodium diet compared to their normal diet was "about the same effect you'd see for a first-line blood pressure medication."

"In addition, that drop happened pretty quickly and was consistent for people with normal blood pressure, slightly high blood pressure or those already on medications," Allen said.

Commentary

According to Allen, the study is the first to "show that people who are already on blood pressure medication can lower their blood pressure even more by limiting sodium." Around 70% to 75% of participants in the study saw a reduction in their blood pressure after lowering their sodium consumption.

"Most people today eat way too much salt because it's added into nearly everything we eat," said Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health, who was not involved in the study. "…It's in foods you'd not expect to have a lot of salt: A couple of slices of bread could have 400 or 500 milligrams of salt; a pickle has a full day’s worth of salt; and a bowl of soup could have several days’ worth of salt in it."

"A teaspoon of salt may seem like a small amount. However, that added salt seems to have an effect on blood pressure that is surprisingly large," Freeman added.

To reduce the sodium in your diet, Allen recommends carefully reading food labels, which is what the dietitians in the study did to choose low-sodium foods. Some low-sodium foods include quick oats, Greek yogurt, grapes, grilled chicken, and low-sodium versions of soup, breads, and peanut butter.

"They were the low-salt versions of vegetable lasagna," Allen said. "They were apples and bananas and things everyone could get at the grocery store. They were not specially prepared by a chef."

Allen also noted that there are no significant side effects of eating a low-sodium diet, aside from potentially adjusting to blander foods.

"When you go from a high-salt diet to a low-salt diet, everything tastes bland," she said. "I want to encourage people to stick with it because your taste buds do adjust within a couple of weeks or so, and you really do get taste and flavor back and normal things will taste very salty."

"Taste bud adjustment takes a little bit longer, but the blood pressure improvements are pretty quick," Allen added. (Searing, Washington Post, 12/4; LaMotte, CNN, 11/11; Gupta et al., JAMA, 11/11)

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