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
Key Clinical Takeaways
Amid an ever-changing landscape of dietary fads and information, it is important to remember that the health benefits of DASH are supported by decades of evidence that demonstrate its benefits for lowering BP, as well as diabetes management, cholesterol management, and cancer prevention. Not all dietary patterns, especially newer ones, have the same level of evidence to back their utility, said Dr Steinberg.
“I would like to reiterate that DASH is not just about sodium. In fact, when it comes to counseling patients who need to lower their BP, reducing salt intake is not always the key to success. When increased consumption of important nutrients like potassium, magnesium, protein, and phosphorous takes center-stage, the synergy between these dietary components may make lowering sodium intake much less necessary in many cases,” she said.
“If the principles of DASH are followed appropriately, DASH can be very beneficial even to patients who consume higher amounts of salt,” she added.
However, Dr Steinberg noted, it is important for dietitians to keep in mind that DASH can be difficult for patients to follow. Population-level data show that less than 1% of the US population fully adhere to DASH, and only 20% get about halfway there.7 In order to fully adhere to the principles and recommendations of DASH, patients often require extra care and support from dietitians to ensure they are able to meet appropriate nutrient targets, she said.
1. DASH eating plan. National Heart, Lung, and Blood Institute. National Institutes of Health. https://www.nhlbi.nih.gov/health-topics/dash-eating-plan. Accessed June 24, 2019.
2. Appel LJ, Moore TJ, Obarzanek E, et al. A clinical trial of the effects of dietary patterns on blood pressure. N Eng J Med. 1997;336:1117-1124. doi:10.1056/NEJM199704173361601.
3. Dietary guidelines for Americans 2015-2020, 8th ed. US Department of Agriculture. https://www.dietaryguidelines.gov/sites/default/files/2019-05/2015-2020_Dietary_Guidelines.pdf. Accessed June 24, 2019.
4. Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018;71:e13-e115. https://doi.org/10.1161/HYP.0000000000000065.
5. Tyson CC, Lin PH, Corsino L, et al. Short-term effects of the DASH diet in adults with moderate chronic kidney disease: a pilot feeding study. Clinical Kidney Journal. 2016;9(4):593-598. https://doi.org/10.1093/ckj/sfw046.
6. Nutrition and dialysis. National Kidney Foundation. https://www.kidney.org/nutrition/Dialysis. Accessed June 24, 2019.
7. Mellen PB, Gao SK, Vitolins MZ, Goff DC Jr. Deteriorating dietary habits among adults with hypertension: DASH dietary accordance, NHANES 1988-1994 and 1999-2004. Arch Intern Med. 2008;168(3):308-14. doi:10.1001/archinternmed.2007.119.