Cut the salt
By BRIAN DOCTROW, PH.D., NATIONAL INSTITUTES OF HEALTH
.webp)
The findings suggest that consuming less
sodium could have health benefits in a wide range of people.
Half of all Americans have high blood
pressure, or hypertension. Blood pressure is considered high when systolic
readings (the top number, the pressure when blood is pumped out of the heart)
are consistently over 130 mm Hg or diastolic readings (the bottom number,
between heartbeats when the heart is filling with blood) are 80 mm Hg or
higher.
Role of Sodium in Hypertension
Although sodium is crucial to the human body,
too much contributes to high blood pressure. The sensitivity of blood pressure
to sodium, however, varies from person to person. This makes it difficult to
determine what counts as a healthy amount of sodium in someone’s diet. Also,
most studies of low-sodium diets have excluded people taking blood
pressure-lowering medications. So, it isn’t clear how much reducing sodium
intake would affect people taking these medications.
Research Study on Dietary Sodium and Blood
Pressure
An NIH-funded research team led by Dr. Deepak
Gupta at Vanderbilt University Medical Center studied the effect of dietary
sodium on blood pressure in 213 people, ages 50-75 (65% women and 64% Black).
Participants with both normal and high blood pressures were enrolled between
April 2021 and February 2023 in Chicago, Illinois and Birmingham, Alabama. Some
were taking medication to control their high blood pressure.
The participants were randomly assigned to a
high- or low-sodium diet for a week. Those on the high-sodium diet added 2,200
mg of sodium per day to their usual diets. Those on the low-sodium diet were
provided with a week’s worth of low-sodium meals, snacks, and beverages. The
diet provided an average of 500 mg of sodium per day.
The researchers measured participants’ blood
pressures after a week. Then the participants switched to the other diet for a
week, and their blood pressures were measured again. Blood pressures were
averages of measurements taken over 24 hours during normal daily activities.
The results appeared in JAMA on
November 11, 2023.
Significant Findings and Implications
Nearly 75% of participants had lower systolic blood pressure on the low-sodium diet than on the high-sodium diet, with an average drop of 7 mm Hg. Compared with their usual diets, 72% of the participants had lower systolic blood pressure on the low-sodium diet, with an average drop of 6 mm Hg.
The effect of dietary sodium didn’t depend on whether
a person had high blood pressure to begin with. It also wasn’t affected by
whether they were on medication for high blood pressure.
These reductions in blood pressure could have significant health benefits. The findings support lowering dietary sodium to reduce blood pressure. The effect of the low-sodium diet was like that of a common first-line medication for high blood pressure.
The results also suggest
that less sodium could help a wide range of people, including those who are
already taking blood pressure-lowering medications.
“Just as any physical activity is better than
none for most people, any sodium reduction from the current usual diet is
likely better than none,” Gupta says.
For more on this study, see New Study Reveals
Universal Blood Pressure Reduction Strategy.
Reference: “Effect of Dietary Sodium on Blood
Pressure: A Crossover Trial” by Deepak K. Gupta, Cora E. Lewis, Krista A.
Varady, Yan Ru Su, Meena S. Madhur, Daniel T. Lackland, Jared P. Reis, Thomas
J. Wang, Donald M. Lloyd-Jones and Norrina B. Allen, 11 November 2023, JAMA.
DOI: 10.1001/jama.2023.23651
Funding: NIH’s National Heart, Lung, and
Blood Institute (NHLBI), National Institute of Diabetes and Digestive and
Kidney Diseases (NIDDK), National Cancer Institute (NCI), and National Center
for Advancing Translational Sciences (NCATS); American Heart Association.
