What’s the effect of a particular diet on lowering blood pressure? That’s the question researchers set out to answer in the ’90s when they randomly assigned 456 people to one of three diets:
1. What they called “a standard American diet,” emphasizing red and processed meats; refined grains like white rice and white bread; sweets and sugar-sweetened beverages.
2. A diet similar to the standard American diet, except with more fruits and vegetables and fewer snacks and sweets.
3. A diet high in fruits, vegetables and whole grains; moderately high in lean protein such as low-fat dairy, fish and chicken; and high in minerals and fiber.
Each of the three diets provided around 3,000 milligrams (mg) of sodium per day, which is more than what’s recommended in the Dietary Guidelines for Americans, but less than the average sodium intake for Americans (3,400 mg). Diets number 2 and 3, however, were richer in fiber as well as nutrients like potassium, magnesium, calcium and protein — all of which are thought to help lower blood pressure.
The landmark study, which was published in 1997 in The New England Journal of Medicine, found that the third diet — the one chock full of fruits, veggies, whole grains and some lean protein — was more effective in reducing blood pressure than the other two. What’s more, participants with high blood pressure (hypertension) who were assigned to the third diet showed greater decreases in blood pressure than those without hypertension.
In the years since, researchers have found that what’s known as the dietary approaches to stop hypertension (DASH) diet has also been shown to lower LDL cholesterol (the “bad” cholesterol), which along with high blood pressure is a major risk factor for cardiovascular disease. No surprise, then, that DASH tops the list of the American Heart Association’s top 10 heart-healthy diets.