DASH Diet May Substantially Lower Risk for CHD as Well as Blood Pressure

Laurie Barclay, MD

September 01, 2010

September 1, 2010 — The Dietary Approaches to Stop Hypertension (DASH) diet may substantially lower the risk for coronary heart disease (CHD) as well as blood pressure, according to the results of a randomized controlled trial reported August 31 online in Circulation. The effects of the DASH diet were strongest in blacks.

The 2005 US Dietary Guidelines and the American Heart Association have recommended the DASH diet, which emphasizes fruits, vegetables, low-fat dairy products, whole grains, poultry, fish, and nuts, while reducing intake of fats, red meat, sweets, and sugar-containing beverages.

"This study provides further evidence that we can make a significant impact on the heart health of the general population by promoting the DASH eating plan," said study coauthor Nisa M. Maruthur, MD, MHS, an assistant professor of medicine at Johns Hopkins Medical Institutions in Baltimore, Maryland, in a news release.

Using data from the DASH trial, the investigators applied the Framingham risk equations to calculate 10-year risk for the development of CHD among 459 individuals with prehypertension or stage I hypertension who were not taking antihypertensive medication. Participants were randomly assigned to 1 of 3 diets: a control diet, a diet rich in fruits and vegetables (F/V), or DASH, while weight was held constant. The primary outcome of this secondary analysis was estimated 10-year CHD risk.

Mean age was 44.7 ± 10.7 years among 436 participants with complete data; 51% were men, and 60% were black. Median 10-year CHD risk was 0.98% at baseline and was decreased in all groups.

For the F/V diet vs the control diet, the relative risk ratio (RR) comparing 8-week vs baseline 10-year CHD risk was 0.93 (95% confidence interval [CI], 0.85 - 1.02; P = .12). For DASH vs the control diet, however, the relative RR was 0.82 (95% CI, 0.75 - 0.90; P < .001). Relative RR for DASH vs F/V was 0.89 (95% CI, 0.81 - 0.97; P = .012). Findings were similar across subgroups, except for an interaction between dietary pattern and race suggesting a greater risk reduction in black patients vs white patients (P for interaction = .038).

"The blood pressure reduction in blacks seemed to be somewhat greater than in whites," Dr. Maruthur said. "Blacks seem to be particularly sensitive to the blood-pressure-lowering effects of the DASH diet."

In addition, the DASH diet was associated with an average 8% reduction in low-density lipoprotein (LDL) cholesterol levels and a reduction in systolic blood pressure by 6 mm Hg. Glucose levels did not change significantly.

"Compared with control and F/V, the DASH diet reduced estimated 10-year CHD risk by 18% and 11%, respectively," the study authors write. "In addition to reducing blood pressure, the DASH diet should substantially reduce the risk of CHD."

Limitations of this study include reduced sample size and limited power in the subgroup of whites, and estimation of 10-year CHD risk from the Framingham risk equations.

"This is not a diet that is difficult to maintain – [i]t includes all types of foods," Dr. Maruthur concluded. "It is a way of eating recommended in the American Heart Association's 2020 Strategic Goals, in the 2006 American Heart Association diet and lifestyle recommendations, and in the US Dietary Guidelines for Americans. We and others have shown that eating this diet should have great public health benefits given the enormous and persistent burden of coronary heart disease."

There was no project-specific funding for this study. Lead author Steven Chen was supported by the Johns Hopkins Predoctoral Clinical Research Training Program grant from the National Center for Research Resources (NCRR) in Bethesda, Maryland. Dr. Maruthur was supported by a training grant from the National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH). The DASH trial was supported by the NHLBI, the Office of Research on Minority Health, and the NCRR of the NIH. The study authors have disclosed no relevant financial relationships.

Circulation. Published online August 31, 2010.

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