An Observational Analysis From the DASH Trial
Background:
The DASH diet has been found to lower blood pressure (BP) and low-density lipoprotein cholesterol levels.
Objective:
To compare diets rich in fruits and vegetables with a typical American diet in their effects on cardiovascular injury in middle-aged adults without known preexisting cardiovascular disease (CVD).
Design:
Observational study based on a 3-group, parallel-design, randomized trial conducted in the United States from 1994 to 1996. (ClinicalTrials.gov: NCT00000544)
Setting:
3 of the 4 original clinical trial centers.
Participants:
326 of the original 459 trial participants with available stored specimens.
Intervention:
Participants were randomly assigned to 8 weeks of monitored feeding with a control diet typical of what many Americans eat; a diet rich in fruits and vegetables but otherwise similar to the control diet; or the DASH diet, which is rich in fruits, vegetables, low-fat dairy, and fiber and has low levels of saturated fat and cholesterol. Weight was kept constant throughout feeding.
Measurements:
Biomarkers collected at baseline and 8 weeks: high-sensitivity cardiac troponin I (hs-cTnI), N-terminal pro–B-type natriuretic peptide (NT-proBNP), and high-sensitivity C-reactive protein (hs-CRP).
Results:
The mean age of participants was 45.2 years, 48% were women, 49% were black, and mean baseline BP was 131/85 mm Hg. Compared with the control diet, the fruit-and-vegetable diet reduced hs-cTnI levels by 0.5 ng/L (95% CI, −0.9 to −0.2 ng/L) and NT-proBNP levels by 0.3 pg/mL (CI, −0.5 to −0.1 pg/mL). Compared with the control diet, the DASH diet reduced hs-cTnI levels by 0.5 ng/L (CI, −0.9 to −0.1 ng/L) and NT-proBNP levels by 0.3 pg/mL (CI, −0.5 to −0.04 pg/mL). Levels of hs-CRP did not differ among diets. None of the markers differed between the fruit-and-vegetable and DASH diets.
Limitation:
Short duration, missing specimens, and an inability to isolate the effects of specific foods or micronutrients.
Conclusion:
Diets rich in fruits and vegetables given over 8 weeks were associated with lower levels of markers for subclinical cardiac damage and strain in adults without preexisting CVD.
Primary Funding Source:
National Institutes of Health, National Heart, Lung, and Blood Institute
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