Compared with following a traditional Western diet, adherence with both the DASH (Dietary Approaches to Stop Hypertension) diet and a dietary pattern rich in fruits and vegetables reduced 10-year risk for atherosclerotic cardiovascular disease (ASCVD) by approximately 10% in a group of adults from the original landmark DASH trial.
The benefit, however, was not consistent across demographics, according to authors of the analysis, who report that effects were greater among women and Black adults.
The observation could have significant implications for diet as a therapeutic intervention, according to the investigators from Beth Israel Deaconess Medical Center (BIDMC), in Boston.
“While physicians and patients rely on the extensive data available when choosing appropriate pharmacologic therapy to prevent atherosclerotic cardiovascular disease, there's limited evidence to inform expectations for risk reductions from established lifestyle interventions," said study investigator Stephen Jurashcek, MD, PhD, a clinician-researcher in the department of medicine at BIDMC, in a statement from BIDMC.
"Our study suggests that the benefits associated with these diets may vary by sex and race.” Jurashcek explained that while the fruit and vegetable diet prescribed in the study reduced risk for women and Black participants, “the effect with the DASH diet was twice as large in women and 4 times as large in Black adults."
The original National Heart, Lung, and Blood Institute-sponsored DASH trial, launched in 1993, reflected a dearth of evidence on the impact of nutrition on cardiovascular health and was designed to evaluate the differential effects of specific diets on lowering blood pressure. Participants in the multicenter trial were randomized to 1 of 3 dietary approaches: a typical “Western” diet (control; low in fiber, high in fat and sodium), a diet heavy in fruit and vegetables, or the DASH diet, which encouraged high intake of fruits, vegetables, and low-fat dairy products, and had a favorable macronutrient profile. The DASH trial cohort numbered 459 adults aged 22 to 75 years. The group was approximately half women, and half the cohort was black.
The original findings demonstrated greater reductions in both systolic and diastolic blood pressure (5.5 and 3.0 mm Hg, respectively) with the DASH diet vs the Western control diet and larger decreases as well (systolic blood pressure [SBP] of 2.8 mm Hg greater and diastolic blood pressure [DBP] reductions of 1.1 mm Hg) with the fruits and vegetables diet compared with the control diet.
The research team’s objective for the current analysis of the DASH trial data was to evaluate effects of the 3 dietary approaches on 10-year risk of ASCVD based on blood pressure and lipid measurements made before and after the intervention period of 8 weeks.
Using the American College of Cardiology/American Heart Association Pooled Cohort Equation the researchers found that adherence to the DASH diet vs the control diet during the trial was associated with a -10.3% (95% CI, -14.4 to -5.9) reduction in 10-year ASCVD risk. Findings were similar when they compared the results of following the control diet with following the fruits and vegetables diet with the latter associated with a -9.9% (95% CI, -14.0 to -5.5) reduction in 10-year ASCVD risk score. The impact of both regimens, the team observed, was greater among women and Black adults in the cohort.
Other differences by demographic were pronounced, with DASH-related risk reduction of approximately 13% among women vs slightly more than 6% among men, according to the BIDMC statement. The difference in impact of the DAHS diet between Black and non-Black participants was even more stark at nearly 14% among Black adults and 3% among non-Black adults.
There were no significant differences in effect on 10-year ASCVD risk when investigators compared adherence to the DASH diet with following the fruits and vegetable diet (-0.4% [95% CI, -6.9 to 6.5]).
When they looked more closely at the relative contribution to risk reduction of changes in blood pressure and lipid measures the BIDMC researchers found decreases attributable to differences in SBP alone with the DASH diet were -14.6% (95% CI, -17.3 to -11.7) and -7.9% (95% CI, -10.9 to -4.8) with the fruits and vegetables diet. When compared with the Western control diet, the net relative advantage was higher (7.2%) for the DASH regimen compared to the fruits and vegetables diet.
However, investigators pointed out this reduction was offset by the impact of the DASH diet on high-density lipoprotein, which increased 10-year risk score by 8.8% (95% CI, 5.5 to 12.3) versus the more neutral effect of -1.9% (95% CI, -5.0 to 1.2) observed with the fruits and vegetables diet.
"The findings could have major implications for clinical practitioners and policy makers alike," said lead investigator Sun Young Jeong, MD, MPH, an internal medicine resident at BIDMC, in BIDMC statement. "Cardiovascular disease is the leading cause of death in women and hypertension is also more strongly linked with heart failure and death in women than men.”
"Similarly, disparities in access to healthy foods has been a major focus of policy efforts to promote higher intake of fruits and vegetables among Black adults," said Juraschek. "Our study suggests that the DASH dietary pattern may offer Black adults more prevention benefits than the emphasis on fruits and vegetables alone. This is particularly relevant as dietary pattern has been identified as one of the most important mediators of hypertension risk among Black adults."
Reference: Jeong SY, Wee CC, Kovell LC, et al. Effects of diet on 10-year atherosclerotic cardiovascular disease risk (from the DASH trial). Am J Cardiol. 2023;187:10-17. Published online ahead of print. doi:10.1016/j.amjcard.2022.10.019