CHICAGO — Few adults with known hypertension are following the DASH diet plan, even though some evidence suggests that it is roughly the equivalent of being on a single blood pressure medication.
Moreover, accordance with the Dietary Approaches to Stop Hypertension (DASH) plan has deteriorated since it was incorporated into in national guidelines, Dr. Philip Mellen said at the annual meeting of the American Society of Hypertension.
“We appear to be improving somewhat with respect to awareness of hypertension and treatment of hypertension,” he said during a press briefing. “But overall, dietary patterns appear to be doing worse over time.”
The landmark 1997 DASH trial showed that a diet rich in fruits, vegetables, grains, and low-fat diary products lowered blood pressure among patients with hypertension by an average of 11.4 mm Hg systolic and 5.5 mm Hg diastolic (N. Engl. J. Med. 1997;336:1117-24).
The dietary guidelines were incorporated into the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure reports in 1998 (JNC 6) and 2003 (JNC 7).
Dr. Mellen and his colleagues at Wake Forest University, Winston-Salem, N.C., used 1999-2004 data from the ongoing National Health and Nutrition Examination Survey (NHANES) IV to generate a DASH score for 4,386 adults with hypertension. Scores were based on self-reported 24-hour intake of nine target nutrients identified in the study (fat, saturated fat, protein, cholesterol, fiber, magnesium, calcium, potassium, and sodium). Individuals with a score of 4.5 or more were considered accordant with the DASH diet. (The data did not indicate whether any of the participants had been instructed to follow the DASH diet.) These results were compared with scores calculated for 4,556 adults with hypertension in the NHANES III 1988-1994 survey.
DASH accordance fell significantly from 29.3% in NHANES III to 21.7% in NHANES IV.
The decline was due largely to significantly fewer Americans in the recent survey reaching targets for total fat, fiber, and magnesium, Dr. Mellen said.
The percentage of patients achieving the DASH goal of reducing total fat intake to less than 27% of calories fell from 43% in NHANES III to 36% in NHANES IV.
Similarly, the percentage of participants on a 2,100-kcal diet eating the DASH recommended 31 grams of fiber daily decreased significantly (20% vs. 12%), as did the percentage ingesting the target 500 mg a day of magnesium (14% vs. 6%).
In a multivariate analysis that adjusted for caloric intake and poverty index ratio, participants were significantly more likely to be DASH-accordant if they were aged 40-59 years (odds ratio 2.75, versus those aged 20-39 years); were aged 60 years or older (OR 3.94, versus those aged 20-39 years); had more than a high school education (OR 1.80); or had diabetes (OR 1.53).
Blacks were significantly less likely than others to follow the DASH diet (OR 0.61), while there was a nonsignificant trend toward higher accordance among Mexican Americans compared with whites, Dr. Mellen said. Accordance did not differ between men and women.
Limited access to fresh fruits and vegetables in urban settings may contribute to poorer accordance among blacks and those with less education, he said in an interview.
Although treatment and awareness are improving, 'overall, dietary patterns appear to be doing worse over time.' DR. MELLEN