Dissecting DASH: What the 1993 study still says about heart health

A secondary analysis of the decades-old DASH-Sodium trial found the popular DASH diet, combined with a reduced sodium intake, successfully lowered systolic blood pressure in a hypertension-prone population, according to a new study published in the Journal of the American College of Cardiology.

For years the DASH (Dietary Approaches to Stop Hypertension) diet, which is rich in fruits, vegetables and low-fat dairy products and reduced in saturated fat and cholesterol, has proven to lower baseline blood pressure for heart patients with high blood pressure. DASH is heralded by clinicians, who recommend the diet to any adults with prehypertension or stage 1 hypertension, as well as the global population. The DASH-Sodium trial was conducted in the late 90s as a follow-up to the original study.

Still, though the effects of DASH and reduced sodium intake have been previously reported, no information exists about the effects of these interventions on different blood pressure (BP) levels, first author Stephen P. Juraschek, MD, PhD, and colleagues wrote in the JACC study. In their own work, Juraschek et al. aimed to quantify the BP-lowering effects of sodium reduction alone, the DASH diet alone with either low or high sodium intake, and a combination of the two.

The researchers evaluated 412 patients from the DASH-Sodium trial, 57 percent of whom were women and 57 percent of whom were black. Patients were an average 48 years old with a mean blood pressure of 135/86 mm Hg. Individuals were randomized to either the DASH diet—a regimen high in whole grains, poultry, fish and nuts and reduced in red meat, sweets and sugary drinks—or a control diet, which was typical of what most Americans eat.

All participants, DASH or otherwise, were fed each of three sodium levels: low, medium and high, Juraschek and co-authors wrote. The high level reflected average sodium intake in the U.S.; the mid-level fell in line with current sodium recommendations.

The authors found the DASH diet lowered systolic blood pressure (SBP) significantly throughout the patient pool, particularly among individuals with higher levels of baseline SBP. In both the control and DASH diets, reducing salt intake from high to low levels lowered SBP in itself, while the effects of the DASH diet differed by sodium level.

“These findings demonstrate that the individual and combined effects from both sodium reduction and the DASH diet are profound, particularly in hypertensive persons with higher BP,” the authors wrote.

They said their findings had important clinical and public health implications, including the reinforcement that the DASH diet, coupled with a decreased salt intake, can significantly lower blood pressure in at-risk patients.

“Our findings suggest that most adults with uncontrolled BP can experience substantial reductions in SBP from dietary changes alone, reinforcing the importance of lifestyle interventions in the management of hypertension,” Juraschek and co-authors wrote. “The SBP reductions observed in those with prehypertension are lesser than those with hypertension, but still should lower the risk of subsequent cardiovascular disease.”