Can the Dietary Approaches to Stop Hypertension (DASH) diet lower my blood pressure?

The DASH diet promotes fruit, vegetable, and low-fat dairy food consumption while reducing saturated fat and cholesterol intake.¹ It is recommended for the management of hypertension based on the extensive evidence of its blood pressure lowering effects. Studies have found that the DASH leads to lower systolic blood pressure (SBP) and diastolic blood pressure (DBP).^1-10 Furthermore, people with greater adherence to the diet^5,8 or higher baseline blood pressures^1,2,6 saw larger benefits.

The Dietary Approaches to Stop Hypertension (DASH) Trial was conducted by Appel et al. in 1997.² They enrolled 459 adults with a systolic blood pressure less than 160 mm Hg and a diastolic blood pressure between 80 to 95 mm Hg. Participants were randomized to a control diet (American diet), a fruits-and-vegetables diet, or a combination (DASH) diet for eight weeks. Sodium intake and body weight were controlled for throughout the study. After the eight weeks, the authors discovered an evident gradient across the diets with regards to SBP and DBP. Compared to the control diet, the DASH diet led to a significant reduction in SBP of 5.5 mm Hg (97.5% confidence interval [CI] [7.4 – 3.7], p<0.001) and in DBP of 3.0 mmHg (97.5% CI [4.3 – 1.6], p<0.001).   Compared to the fruits-and-vegetables diet, the DASH diet reduced SBP by 2.7 mm Hg more (p=0.001) and DBP by 1.9 mm Hg more (p=0.002). The reduction in blood pressure on the DASH diet held true both for subjects with hypertension at baseline and for subjects without hypertension. However, subjects with hypertension experienced a greater reduction in blood pressure.

A 2015 meta-analysis by Siervo et al. analyzed randomized controlled trials of adult participants adhering to a DASH diet.¹ In twenty articles reporting on 1917 individuals SBP and DBP of participants following a DASH diet were compared to those of participants following a standard diet, which was the typical American diet in the majority of the studies. Participants following the DASH diet had a significant reduction in SBP of 5.2 mmHg (95% CI [7.0 – 3.4], p<0.001) and in DBP of 2.6 mmHg (95% CI [3.5 – 1.7], p<0.001). Furthermore, those with higher baseline blood pressures had greater responses to the DASH diet in terms of blood pressure reduction.

The diet’s blood pressure lowering effects are greater for those with greater adherence to the diet. In a prospective study of 1409 participants, Maddock et al. assessed the long-term associations between the DASH diet and cardiovascular risk factors over a span of 24 to 28 years.⁵ Data from the Medical Research Council National Survey of Health and Development was used to take a sample of babies born in one week in March 1946. Dietary intake was evaluated at 36, 43, 53, and 60-64 years using 5-day food diaries.The participants were separated into quintiles based on adherence to the diet with the higher quintiles assigned for greater adherence. After adjusting for BMI, smoking, socio-economic status, and physical activity, the authors found a significant trend in reduction for SBP (p=0.01) and a beneficial but nonsignificant trend in reduction for DBP (p=0.08) in favor of the higher quintiles.

Overall, evidence indicates that the DASH diet can lower both SBP and DBP although the evidence for reduction in DBP is somewhat weaker.

^References

1. Siervo M, Lara J, Chowdhury S, Ashor A, Oggioni C, Mathers JC. Effects of the Dietary Approach to Stop Hypertension (DASH) diet on cardiovascular risk factors: a systematic review and meta-analysis. Br J Nutr. 2015;113(1):1-15.
2. Appel LJ, Moore TJ, Obarzanek E, et al. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med. 1997;336(16):1117-1124.
3. Chiavaroli L, Viguiliouk E, Nishi SK, et al. DASH dietary pattern and cardiometabolic outcomes: an umbrella review of systematic reviews and meta-analyses. Nutrients. 2019;11(2).
4. Hashemi R, Rahimlou M, Baghdadian S, Manafi M. Investigating the effect of DASH diet on blood pressure of patients with type 2 diabetes and prehypertension: Randomized clinical trial. Diabetes Metab Syndr. 2019;13(1):1-4.
5. Maddock J, Ziauddeen N, Ambrosini GL, Wong A, Hardy R, Ray S. Adherence to a Dietary Approaches to Stop Hypertension (DASH)-type diet over the life course and associated vascular function: a study based on the MRC 1946 British birth cohort. Br J Nutr. 2018;119(5):581-589.
6. Juraschek SP, Miller ER, 3^rd, Weaver CM, Appel LJ. Effects of sodium reduction and the DASH diet in relation to baseline blood pressure. J Am Coll Cardiol. 2017;70(23):2841-2848.
7. Kucharska A, Gajewska D, Kiedrowski M, et al. The impact of individualised nutritional therapy according to DASH diet on blood pressure, body mass, and selected biochemical parameters in overweight/obese patients with primary arterial hypertension: a prospective randomised study. Kardiol Pol. 2018;76(1):158-165.
8. Najafi A, Faghih S, Hojhabrimanesh A, et al. Greater adherence to the dietary approaches to stop hypertension (DASH) dietary pattern is associated with lower blood pressure in healthy Iranian primary school children. Eur J Nutr. 2018;57(4):1449-1458.
9. Sacks FM, Svetkey LP, Vollmer WM, et al. Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group. N Engl J Med. 2001;344(1):3-10.
10. Ndanuko RN, Tapsell LC, Charlton KE, Neale EP, Batterham MJ. Dietary patterns and blood pressure in adults: a systematic review and meta-analysis of randomized controlled trials. Adv Nutr. 2016;7(1):76-89.