A new study found that reducing daily sodium (salt) intake by one teaspoon per day significantly lowered systolic blood pressure in as little as a week (JAMA, Nov 11, 2023). The study participants were 213 adults, ages 50-75, who had:
• normal blood pressure, or
• high blood pressure and were taking medication for high blood pressure, or
• high blood pressure and were not taking medication for high blood pressure.
After an initial exam and testing, they were put on either a high-sodium diet (2,200 mg of sodium added to their usual diet), or a low-sodium diet (500 mg sodium daily) for one week. They then switched to the opposite diet for one week. The average systolic blood pressures of the participants while they were on their usual diet was 125mm Hg. After a week on the high sodium diet the average was 126mm Hg, and after a week on the low sodium diet the average was 110 mm Hg. Thus the systolic blood pressure was almost the same with the high-sodium diet compared with usual diet. After lowering blood pressure with the low-salt diet and returning to their usual diet, the average blood pressure returned to 125mm Hg.
The Low-Salt and High-Salt Diets Used in the Study
For the Low-Salt Diet, Breakfast was oatmeal, Greek yogurt and grapes.
Lunches included fruit, a bag of chips and either a chicken salad, lentil soup or peanut butter and jelly sandwich.
Supper included fruit, a serving of low-fat milk, and either a low-sodium frozen burrito, a low-sodium frozen vegetable lasagna or a low-sodium rice and vegetable entree.
The high -salt diet consisted of the participant’s usual diet with the addition of two chicken bouillon packets daily, with 1,100 mg of sodium in each packet.
Using a Plant-Based Low-Salt Diet Would Lower Blood Pressure More
A review of 85 studies demonstrated that low-salt diets significantly lower high blood pressure (Circulation, Feb 15, 2021). Combining a plant-based diet with a low-salt diet lowers high blood pressure even more. In people with heart disease, switching to a plant-based, low-salt diet (a modified DASH diet) lowered high blood pressure and reduced markers of heart muscle damage in just four weeks (J Am Coll Cardiol, Jun 2021;77(21):2625-2634). Those on the low-salt DASH diet had the lowest levels of high sensitivity cardiac troponin I (hs-cTnI), which measures heart muscle damage, and N-terminal pro-brain natriuretic peptide (NT-proBNP), which measures loss of heart muscle strength. Plants are good sources of potassium, and a high-potassium diet can counter some of the harmful effects of taking in too much salt (JAMA Pediatr, June 2015;169(6):560-568).
Low-Salt Does Not Mean No-Salt
In a study of the modified DASH diet mentioned above, the low-salt group consumed 50 mmol of sodium per day, which is about 1145mg of sodium or half a teaspoon of table salt. To control how much salt you eat, I recommend that you prepare most of your own foods rather than relying on processed foods or restaurant meals. You have no way to know how much salt is added to restaurant food, and when you start reading the sodium data on processed foods, you will see how quickly your salt levels can go up. Almost all processed foods contain sodium, even the ones that don’t taste salty, such as salad dressing. For example, one serving of Newman’s Classic Oil and Vinegar salad dressing contains 180 mg of sodium; one serving of plain Tostitos corn chips contains 115mg. Animal products (meat, seafood, poultry, dairy, eggs) also contain sodium, usually about 100mg or more per serving.
Many cases of high blood pressure can be controlled with a high-plant, low-salt diet and other lifestyle changes that include:
• trying to exercise every day
• maintaining a healthful weight
• restricting or avoiding alcohol
• avoiding smoking and second hand smoke
• keeping blood levels of hydroxy vitamin D above 30 ng/mL