High blood pressure affects 108 million adults, increasing risk for heart attacks, the leading cause of death in the United States. A Harvard study of 412 adults found that a low-salt version of the DASH diet dramatically lowered both high blood pressure and markers of heart muscle damage in just four weeks (J Am Coll Cardiol, Jun 2021;77(21):2625–2634). The authors showed that those on the low-salt DASH diet had the lowest levels of:
• high sensitivity cardiac troponin I (hs-cTnI), which measures heart muscle damage
• N-terminal pro-brain natriuretic peptide (NT-proBNP), which measures loss of heart muscle strength
Most People with High Blood Pressure Should Be on a Low Salt Diet
This new study and several others have changed my opinion about the importance of salt restriction for people with high blood pressure. Some earlier papers showed that salt restriction lowered systolic blood pressure by less than 5 mm Hg and diastolic blood pressure by only 2.5 mm Hg (JAMA Intern Med, 2014;174(4):516-524). However, the subjects in that study were already on a high-plant diet which, by itself, can lower high blood pressure because plants are loaded with 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). A review of 85 studies, following participants for up to three years, found that low-salt diets significantly lower high blood pressure (Circulation, Feb 15, 2021), and the new study from Harvard confirms the importance of following both a high-plant and a low-salt diet for patients with high blood pressure.
A low-salt diet does not mean no-salt. In the Harvard study, 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, you will need to 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 1145 mg/day will get used up. Almost all processed foods contain sodium, even the ones that don’t taste salty, such as salad dressing. For example, one serving (2 tablespoons) of Newman’s Classic Oil and Vinegar salad dressing is 180mg; one serving (22 Bite Size chips) of plain Tostitos is 115mg. Animal products (meat, seafood, poultry, dairy, eggs) also contain sodium, usually about 100mg or more per serving.
The DASH Diet
The DASH diet was developed in the 1990s by the U.S National Institutes of Health (NIH), and has been studied extensively by the Harvard School of Public Health and many other researchers. The diet is plant-focused, with lots of vegetables, fruits, nuts, seeds, whole grains and heart-healthy fats, and with limited amounts of dairy and lean meats. Serving sizes of different food groups can be adjusted based on calorie needs. The DASH diet is similar to the many healthful Mediterranean-type diets. The original DASH diet was not specifically low-salt, but that change is easy to make.
I have recommended a slightly modified version of the DASH diet for many years, and all of Diana’s healthful recipes are based on it.
Here’s a day on my modified low-salt DASH diet:
• Up to 8 servings of cooked WHOLE grains (not products made from flour)
• At least 5 vegetables
• At least 5 fruits
• Up to 3 servings of plain yogurt or cheese (optional)
• 2 servings of seafood per week (I recommend that you avoid meat from mammals)
• Beans or legumes (no limit)
• A few handfuls of unsalted nuts or snack seeds
• A few tablespoons of olive oil (optional)
(DASH diet serving sizes are typically 1 cup of raw fruits or vegetables, 1/2 cup of other foods)
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
• avoiding alcohol
• avoiding smoking and second hand smoke
• keeping blood levels of hydroxy vitamin D above 30 ng/mL
See Check Your Own Blood Pressure