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ENCORE: Effects of DASH diet plus weight management equivalent to high-dose antihypertensive drugs
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Results from the first trial to examine the effects of the Dietary Approaches to Stop Hypertension diet in free-living individuals confirmed that overweight or obese participants with above-normal blood pressure benefited from the intervention, and that the addition of other exercise and weight-loss programs enhanced outcomes.
“Our results confirm the findings of the earlier DASH feeding studies: participants who ate the DASH diet achieved significant BP reductions,” researchers from several U.S. sites wrote.
The researchers randomly assigned 144 healthy, overweight participants to one of two intervention programs from October 2003 to July 2008 as part of the ENCORE trial. Those who met inclusion criteria were not taking antihypertensive medications; had a mean systolic BP of 130 mm Hg to 159 mm Hg and mean diastolic BP of 85 mm Hg to 99 mm Hg; BMI of 25 to 40; and were aged 35 years or older.
Participants were randomly assigned to the DASH diet alone (n=46), DASH diet plus a weight management regimen consisting of aerobic exercise and cognitive-behavioral therapy (n=49) or a control group that maintained usual dietary and exercise habits (n=49).
After a four-month treatment period, participants in both the diet group alone and the diet plus weight management group had significantly lowered systolic BP (P<.001) and diastolic BP (P<.001) compared with the control group. Furthermore, these improvements were greater among participants in the diet and weight management group vs. participants in the diet-only group.
From pretreatment to posttreatment, patients in the diet plus weight management group experienced a 16.1 mm Hg reduction in systolic BP (95% CI, 13-19.2) and 9.9 mm Hg reduction in diastolic BP (95% CI, 8.1-11.6). Those who participated in the diet-only group experienced a 11.2 mm Hg reduction in systolic BP (95% CI, 8.1-14.3) and 7.5 mm Hg reduction in diastolic BP (95% CI, 5.8-9.3). Among those who maintained their usual diet, systolic BP was reduced by 3.4 mm Hg (95% CI, 0.4-6.4) and diastolic BP was reduced by 3.8 mm Hg (95% CI, 2.2-5.5).
At the end of treatment, only six patients in the DASH plus weight management group and seven patients in the DASH only group were classified as hypertensive compared with 19 patients in the control group.
The relative reductions in BP observed among participants in the diet and weight management group were “equivalent to the BP-lowering that physicians could expect from a high dose of antihypertensive drug,” the researchers wrote. “Similar BP reductions have been achieved in placebo-controlled treatment trials and have resulted in a lowering of stroke risk by approximately 40% and a reduction in ischemic heart disease events by about 25%.”
Additionally, participants in both DASH diet intervention groups experienced improvements in CV biomarkers including lower pulse wave velocity (P=.001), larger improvements in flow-mediated dilation (P=.06) and lower left ventricular mass index (P=.26) compared with those in the control group.
The relatively small sample size, highly motivated participants and the labor intensiveness of the program may limit the study findings, according to the researchers, who called for a larger prospective trial. A longer-term follow-up of ENCORE patients is ongoing.
Blumenthal JA. Arch Intern Med. 2010;170:126-135.