What You May Not Know About DASH
Dietary Approaches to Stop Hypertension (DASH) is a well-known dietary pattern with a central goal of lowering blood pressure (BP).1
Although DASH is often regarded as a low-sodium diet, the original conception of DASH was not low-sodium.2 In fact, when appropriate nutrient needs are met, many DASH followers may not need to place as much emphasis on lowering their sodium intake, according to Dori Steinberg, PhD, RD, associate professor at the Duke School of Nursing and director of the Duke Global Digital Health Science Center in Durham, North Carolina.
The original DASH trial, which was performed just over 20 years ago, aimed to test dietary patterns that hit specific targets for a variety of nutrients while simultaneously allowing participants around 3000 mg of sodium daily2 – a much higher allowance than what current guidelines recommend.3
Participants’ diets consisted of high fruit, vegetable, legume and low-fat dairy intake, coupled with reduced consumption of saturated fat, total fat, and cholesterol.2 Potassium, magnesium, and calcium were consumed in amounts near the 75th percentile of US consumption, and high amounts of fiber and protein were also emphasized.2
The trial found that this dietary approach was associated with substantially reduced blood pressure compared with the control diet, which consisted of low fruit, vegetable, and dairy intakes and a fat intake consistent with that of a typical Western diet.2
“Although the synergy between these components is not yet fully understood, the combination of high potassium, magnesium, calcium, and fiber consumption, as well as reduced total fat and saturated fat intake, has been shown to help DASH followers obtain optimum BP benefits rather than focusing primarily on reduced sodium intake,” Dr Steinberg told Nutrition411.
These nutrients can be obtained from a variety of different foods, including fruits, vegetables, legumes, nuts, low-fat dairy products, low-fat protein sources, and whole grains, Dr Steinberg said.
Although reduced sodium intake is not necessarily the primary focus of DASH, as evidenced by the original DASH trial, current dietary guidelines from the US Department of Agriculture note that some patients with elevated BP or hypertension may benefit from limiting sodium intake to 2300 mg or even 1500 mg of sodium per day.3
Indications, Special Populations, and Contraindications
In 2017, the American Heart Association and American College of Cardiology issued hypertension guidelines that lowered the threshold for normal BP to below 120/80 mm Hg for the general population.4 “Individuals who once met criteria for ‘prehypertension’ are now considered to have ‘elevated BP,’ and according to the guidelines, providers should discuss lifestyle approaches with individuals who have a systolic BP between 120 and 130 and a diastolic BP of 80 to 90 mm Hg,” Dr Steinberg told Nutrition411.
When it comes to lifestyle interventions for BP, myriad evidence supports the role of DASH not only among patients with hypertension but also those whose BP falls in the lower range of what is considered “elevated.” In addition, evidence has shown that DASH can be beneficial for the management and prevention of other chronic diseases, including type 2 diabetes, elevated cholesterol, and cancer.
However, because DASH is high in potassium, protein, and phosphorous, this dietary pattern may not be conducive for certain patients with chronic kidney disease (CKD), Dr Steinberg noted.
“My colleague at Duke University, Crystal Tyson, MD, who recently examined special populations in DASH, found that patients with lower stages of CKD may benefit from DASH because it can lower BP, but more research on the long-term safety of DASH in this patient population is still needed,” she said.5
Among patients with advanced CKD, DASH is likely not a viable option. DASH should also not be considered for patients on dialysis, who should instead adhere to dialysis dietary guidelines.6