Blood pressure diet works, but adherence drops among African-Americans

The findings, which appear online Sept. 19 in the Journal of the Academy of Nutrition and Dietetics, suggest that altering traditional recipes to meet nutritional guidelines rather than eliminating certain foods altogether may result in better adherence among African-Americans.

The DASH diet is recognized as the diet of choice for preventing and managing high blood pressure. The diet is rich in fruits, vegetables, and low fat dairy products, and is low in fats and cholesterol.

"Previous research, including results from our ENCORE study, established the DASH diet as an important approach for lowering blood pressure, and for some individuals, it may be an effective alternative to taking medication for hypertension," said James A. Blumenthal, PhD, professor of behavioral medicine in the Department of Psychiatry and Behavioral Science at Duke University Medical Center. "In this study we were interested in whether dietary adherence was related to blood pressure changes and what factors predicted who would adhere to the diet."

The study was a new analysis of data from the ENCORE trial, led by Duke researchers to evaluate the effectiveness of the DASH diet on cardiovascular health. Participants were 144 sedentary, overweight or obese adults, who had high blood pressure and were not taking medication.

Researchers measured a series of clinical and behavioral factors at the start of the study including blood pressure, weight, and physical fitness, as well as dietary habits. Depression, anxiety and social support were also evaluated as potential predictors of adherence to the regimen.

Participants were randomly assigned to one of three treatment groups: the DASH diet alone; the DASH diet in combination with weight-loss counseling and aerobic exercise; or no change in diet and exercise habits.

After four months, participants in the group that got the DASH diet plus weight-loss counseling and exercise lost an average of 19 pounds, while weight remained stable in the other two groups.

Participants in both the DASH diet alone and DASH diet plus counseling groups had significant reductions in blood pressure, with greater adherence to the DASH diet resulting in the largest drops in blood pressure. The finding suggests that that following the DASH diet lowers blood pressure, independent of exercise and weight loss.

However, the addition of weight loss and exercise to the DASH diet promoted even greater reductions in blood pressure and improved other measures of cardiovascular health. "For overweight or obese patients with high blood pressure, clinicians should recommend the DASH diet in conjunction with exercise and weight loss for the best results," said Alan Hinderliter, MD, a cardiologist at the University of North Carolina at Chapel Hill and an investigator in this study.

The researchers noted that African-American participants were less likely than white participants to eat foods recommended in the DASH diet prior to beginning the study. While both African-American and white participants in the DASH treatment groups increased the amount of DASH foods they ate, African-Americans were less likely to adopt the DASH diet compared to their white counterparts. No other demographic, behavioral, or social variable predicted whether participants would adhere to the DASH diet.

"We need to be aware of cultural differences in dietary preferences in order to help people better adopt a DASH-friendly diet," Blumenthal said. "It is important to take into account traditional food choices and cooking practices when attempting to incorporate more DASH foods into daily meal plans."

Culturally sensitive changes to implementing the DASH diet, such as modifying traditional "soul food" recipes to meet nutritional recommendations rather than eliminating foods altogether, may result in better adherence among African-Americans.

"Given the success of the DASH diet, we know that changing lifestyles can make a significant difference in people's health," Blumenthal said. "And in the long run, if people are able to maintain changes to their diet and exercise habits, it can lead to a lower risk for heart attack and stroke."

In addition to Blumenthal, Duke researchers include Dawn Epstein, Andrew Sherwood, Patrick J. Smith, Carla Caccia, Pao-Hwa Lin, Michael A. Babyak, and Julie J. Johnson. Other researchers include Linda Craighead of Emory University, and Alan Hinderliter of the University of North Carolina at Chapel Hill.

The study was funded with grants from the National Heart, Lung, and Blood Institute (HL074103), and the General Clinical Research Center, National Institutes of Health (M01-RR-30).