Effect Of Dash Diet On Pre- And Stage-1 Hypertensive Individuals In A Free-living Environment

Abstract

BACKGROUND: Dietary Approaches to Stop Hypertension (DASH) has been shown to successfully reduce systolic (SBP) and diastolic blood pressure (DBP) when evaluated in clinically controlled environments but little is known about the efficacy of the DASH diet when it is applied in a free-living environment. PURPOSE: To determine if following the DASH diet in a free-living environment for a 4-week duration decreased SBP and DBP. METHODS: Twenty, pre- and stage-1 hypertensive participants were split into 2 groups; DASH (males N = 5, females N = 5, age = 38.1 ± 11.1) and control (males N = 7, females N = 3, age = 38.5 ± 10.5). The DASH group was instructed how to follow the DASH diet on their own for a 4-week duration while the control group continued their normal diet. SBP, DBP, bodyweight, 3-day food diaries and physical activity questionnaire data were collected pre and post intervention. RESULTS: Group (DASH, control) by gender (males, females) by time (pre, post-intervention) ANCOVAs, with weight change as a co-variate, demonstrated a significant group by time interaction for changes in SBP (p = 0.003) and no significant effects for DBP. The interaction was due to a significant reduction (p = 0.001) in SBP in DASH (pre: 141.3 ± 11.3 mmHg vs. post: 130.7 ± 9.1 mmHg) with no change in SBP in control (pre: 133.5 ± 6.6 mmHg vs. post: 131.9 ± 8.9 mmHg). Bodyweight change was entered as a covariate to ensure significant changes in SBP and DBP were independent of weight loss. Chi-square demonstrated no significant differences in the number of participants per group (n = 4 DASH, n = 1 control) who indicated increasing physical activity during the intervention. Group by time ANOVAs demonstrated significant interactions for K+, total and saturated fat (p ≤ 0.02). These interactions were the result of a significantly greater increase in dietary intake of K+ and decrease in dietary intake of total and saturated fat (p ≤ 0.02) in DASH (D 1267.8 ± 1103.2mg K+, -68.4 ± 35.9g total fat, -22.1 ± 13.1g saturated fat) relative to control (D -40.0 ± 1103.2mg K+, -18.8 ± 19.7g total fat, -3.1 ± 10.0g saturated fat). CONCLUSION: DASH diet followed in a free-living environment significantly reduced SBP independent of weight loss and without significant differences in self-reported physical activity. These changes may be due to differences in K+, total and saturated fat intake.