NHLBI study shows large blood pressure benefit from reduced dietary sodium

May 16, 2000

The lower the amount of sodium in the diet, the lower the blood pressure, for both those with and without hypertension, according to a National Heart, Lung, and Blood Institute (NHLBI)-supported clinical study. The lowest sodium level tested, which produced the lowest blood pressure, was well below the currently recommended intake of 2,400 milligrams a day.

Moreover, the effects of reducing sodium occurred with both a diet similar to what many Americans eat and the "DASH diet," which is rich in vegetables, fruits, and lowfat dairy foods and low in saturated fat, total fat, and cholesterol. The greatest blood pressure reduction occurred with the DASH diet at the lowest intake of dietary sodium.

The blood pressure reductions occurred in men and women and in African Americans and others.

DASH stands for "Dietary Approaches to Stop Hypertension." The findings, which will be presented tomorrow at the American Society of Hypertension (ASH) annual meeting in New York City, are from the DASH-Sodium trial, a multicenter 14-week feeding study.

"This finding should answer the question of whether or not reducing dietary sodium benefits those without hypertension," said NHLBI Director Dr. Claude Lenfant. "Earlier studies had differed in their designs, leading to uncertainty over how worthwhile it is to reduce dietary sodium for those who have not yet developed high blood pressure. This well-controlled study had a diverse group of participants and its finding shows that the benefit is substantial.

"The study also should help establish the best level of sodium consumption for preventing and controlling high blood pressure. The finding suggests that an intake below that now recommended could help many Americans prevent the blood pressure rises that now occur with advancing age."

The new finding is from the second DASH study. The first DASH study examined the effect on blood pressure of whole dietary patterns, rather than of individual nutrients. Its findings, which appeared in the April 17, 1997 issue of The New England Journal of Medicine, showed that the DASH diet significantly and quickly lowered blood pressure.

The DASH diet is low in saturated fat, total fat, and cholesterol. It emphasizes fruits, vegetables, and lowfat dairy foods, and includes whole grains, poultry, fish, and nuts. It is reduced in red meat, sweets, and sugar-containing beverages. It is rich in potassium, calcium, and magnesium, as well as protein and fiber.

The blood pressure reductions in that study occurred without changes in weight, alcohol consumption, or dietary sodium intake. All study participants consumed about 3,000 milligrams daily of dietary sodium, which is slightly below Americans' average consumption.

DASH-Sodium, the second study, was conducted to look at the relationships between blood pressure and various sodium intakes during two different eating patterns.

DASH-Sodium involved 412 participants, aged 22 or older. About 57 percent of the participants were women and about 57 percent were African Americans. Participants had systolic blood pressures of 120-159 mm Hg and diastolic blood pressure of 80-95 mm Hg. About 41 percent had hypertension.

Participants had all of their food provided. They were randomly assigned to one of two dietary plans, each of which was followed at three sodium levels. The two dietary plans were a "usual" diet, typical of what many Americans eat, and the DASH diet. The three sodium levels, each consumed for four weeks, were: a "higher" intake of 3,300 milligrams per day; an "intermediate" intake of 2,400 milligrams per day; and a "lower" intake of 1,500 milligrams per day.

Results showed that reducing dietary sodium lowered blood pressure for both the usual and DASH diets. The lower the sodium intake, the lower the blood pressure.

The biggest reductions in blood pressure were found among those who followed the DASH diet at the lower sodium intake. That combination reduced blood pressure more than either the DASH diet or lower sodium intake alone. The combination worked best for all participants-those with and without hypertension, men and women, and African Americans and others.

Overall, the DASH diet combined with the lower sodium intake reduced systolic blood pressure by an average of 8.9 mm Hg and diastolic blood pressure by an average of 4.5 mm Hg. In those with hypertension, the combination reduced systolic blood pressure by an average of 11.5 mm Hg; in those without hypertension, the combination reduced systolic blood pressure by an average of 7.1 mm Hg.

Other key results from the study are:Those on the lower sodium intake, as well as those on the DASH diet, had fewer headaches. Otherwise, there were no significant differences in adverse effects among the two eating plans or different sodium levels.

"The results show that those with hypertension should follow the DASH eating plan at a reduced sodium intake to help lower their blood pressure," said Dr. Frank Sacks, chair of the DASH-Sodium Steering Committee and Associate Professor of Medicine at Brigham and Women's Hospital and the Harvard Medical School.

DASH-Sodium also found that both sodium reduction and the DASH diet had a substantial effect on the blood pressure of African Americans.

"African Americans have more hypertension than other Americans," said Sacks. "The finding suggests that more than sodium may play a role in African Americans' blood pressure, and they would benefit from adopting an eating plan similar to that of a lower sodium DASH diet."

"The study shows how important it is to reduce sodium in the diet. The findings suggest that the current recommendation for how much dietary sodium Americans should consume may need to be lowered. By reducing their dietary sodium to 1,500 milligrams a day, all Americans, and especially those at high risk for hypertension, can decrease their chance of developing high blood pressure as they age," said Dr. Eva Obarzanek, an NHLBI nutritionist and Project Officer for DASH-Sodium.

"To make that change," she continued, "Americans should cut down on processed foods-the biggest source of sodium in the diet-use food labels as a guide to choose items lower in salt and sodium, flavor foods with spices instead of salt, and remove the salt shaker from the table. The food industry also needs to help by reducing the amount of salt they put into food products. It would help to make more low-salt food products available.

"Reducing sodium benefits blood pressure whatever your eating plan," added Obarzanek. "But for a true winning combination, follow the DASH diet and lower your intake of sodium."
-end-
Both DASH studies were conducted by investigators from the Brigham and Women's Hospital in Boston, MA, Duke University Medical Center in Durham, NC, The Johns Hopkins University in Baltimore, MD, the Pennington Biomedical Research Center of the Louisiana State University in Baton Rouge, LA, and the Kaiser Permanente Center for Health Research in Portland, OR.

To arrange an interview about DASH-Sodium, contact the NHLBI Communications Office at (301) 496-4236.

NHLBI press releases, a high blood pressure Web site, and other materials are available online at www.nhlbi.nih.gov.

NIH/National Heart, Lung and Blood Institute

Related Blood Pressure Articles from Brightsurf:

Children who take steroids at increased risk for diabetes, high blood pressure, blood clots
Children who take oral steroids to treat asthma or autoimmune diseases have an increased risk of diabetes, high blood pressure, and blood clots, according to Rutgers researchers.

High blood pressure treatment linked to less risk for drop in blood pressure upon standing
Treatment to lower blood pressure did not increase and may decrease the risk of extreme drops in blood pressure upon standing from a sitting position.

Changes in blood pressure control over 2 decades among US adults with high blood pressure
National survey data were used to examine how blood pressure control changed overall among U.S. adults with high blood pressure between 1999-2000 and 2017-2018 and by age, race, insurance type and access to health care.

Transient increase in blood pressure promotes some blood vessel growth
Blood vessels are the body's transportation system, carrying oxygen and nutrients to cells and whisking away waste.

Effect of reducing blood pressure medications on blood pressure control in older adults
Whether the amount of blood pressure medications taken by older adults could be reduced safely and without a significant change in short-term blood pressure control was the objective of this randomized clinical trial that included 534 adults 80 and older.

Brain blood flow sensor discovery could aid treatments for high blood pressure & dementia
A study led by researchers at UCL has discovered the mechanism that allows the brain to monitor its own blood supply, a finding in rats which may help to find new treatments for human conditions including hypertension (high blood pressure) and dementia.

Here's something that will raise your blood pressure
The apelin receptor (APJ) has been presumed to play an important role in the contraction of blood vessels involved in blood pressure regulation.

New strategy for treating high blood pressure
The key to treating blood pressure might lie in people who are 'resistant' to developing high blood pressure even when they eat high salt diets, shows new research published today in Experimental Physiology.

Arm cuff blood pressure measurements may fall short for predicting heart disease risk in some people with resistant high blood pressure
A measurement of central blood pressure in people with difficult-to-treat high blood pressure could help reduce risk of heart disease better than traditional arm cuff readings for some patients, according to preliminary research presented at the American Heart Association's Hypertension 2019 Scientific Sessions.

Heating pads may lower blood pressure in people with high blood pressure when lying down
In people with supine hypertension due to autonomic failure, a condition that increases blood pressure when lying down, overnight heat therapy significantly decreased systolic blood pressure compared to a placebo.

Read More: Blood Pressure News and Blood Pressure Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.