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The DASH diet

This HEART UK Nutrition Academy webpage has been funded by Novartis Pharmaceuticals UK Ltd who have had no input into the content or development of this material.
 

The DASH diet is highly effective for managing hypertension and blood lipids and is supported by a compelling body of research.

Take home messages

  • The DASH diet was specifically developed to lower high blood pressure.
  • High blood pressure is a significant risk factor for cardiovascular disease and is responsible for almost half of coronary heart disease deaths in the UK.
  • DASH is a plant-based diet that prioritises fruit, vegetables, whole grains, nuts, seeds and legumes. It contains moderate amounts of low fat dairy and limits red and processed meat.
  • The DASH diet:
    • is rich in fibre
    • is rich in minerals associated with lowering blood pressure - potassium, calcium and magnesium
    • has a positive unsaturated fat to saturated fat ratio
    • is low in sugars and salt (sodium).
  • Randomised controlled trials have consistently demonstrated DASH to be highly effective at:
    • lowering systolic blood pressure by 5.5mmHg and diastolic blood pressure by 3.0 mmHg
    • improving blood lipids by as much as -0.35mmol/L for total and -0.28mmol/L for LDL cholesterol.  This is attributed the higher unsaturated fat and lower saturated fat content, as well as the inclusion of whole grains, fruit, vegetables, nuts and legumes.
  • Cohort studies have also demonstrated a strong inverse association between compliance with the DASH diet and CVD incidence and mortality.

The Dietary Approaches to Stop Hypertension (DASH) diet was developed in 1995 in the US and has since been through several variations1,2. The aim of the diet is to tackle one of the main modifiable risk factors for cardiovascular diseases (CVD) – hypertension1,2. According to the latest Global Burden of Disease data, high systolic blood pressure is the underlying cause of over half of CVD deaths globally3.

Why lower high blood pressure?

High blood pressure, along with dyslipidaemia, is one of the key risk factors for CVD13 . In the UK, hypertension is responsible for3:

  • 44% of all CVD deaths
  • almost half of deaths from coronary heart disease (CHD)
  • 40% of stroke deaths.

High blood pressure contributes significantly to years of ill health and premature deaths – measured as disability-adjusted-life-years (DALYs)3 .

High blood pressure alone is responsible for 1.3 million CVD-related DALYs in the UK, most of which are caused by CHD3,13. This means 1.3 million years of poor quality of life, inability to work, and years of life lost due to premature death.

High blood pressure incidence in the UK13

  • One in three adults have high blood pressure – that's approximately 16 million people.
  • Over a third of those are undiagnosed and at least half are not receiving the most effective treatment.
  • Half of all heart attacks in the UK have been attributed to high blood pressure.

What is the DASH diet?

The DASH diet is predominantly made up of healthy plant foods which have been specifically selected for their blood pressure-lowering potential. It discourages red and processed meat and foods high in saturated fats and/or sugars1,2,4,5.

The DASH diet has been shown to be successful in lowering blood pressure and other metabolic risk factors, as well as the risk of CVD incidence and mortality4,6–12.

The nutrient profile of DASH

The DASH diet was originally developed without salt restrictions and focused on the impact of healthy plant foods, low fat dairy and unsaturated fats with limited red and processed meat, saturated fats and sugary foods and drinks1,7. Later versions also began to incorporate salt restrictions2.

The diet was designed to incorporate the right balance of different foods to deliver a plan that:
  • is high in fibre
  • is high in the minerals associated with lowering blood pressure: calcium, magnesium and potassium
  • is high in antioxidant vitamins such as vitamin C and folate
  • provides moderate quantities of protein
  • prioritises plant foods over animal foods
  • has a favourable fat profile with a higher proportion of unsaturated fats and low saturated fats (saturated fats were halved)
    contains usual salt levels.
Table 1. Nutritional composition of DASH – daily intakes 1,2 
 

Control diet

(usual US intakes)

DASH
Total fat (% total energy) 37% 27%
Saturated fat (% total energy) 16% 6%
PUFA (% total energy) 8% 8%
Carbohydrates (% total energy) 48% (refined) 55% (whole grain)
Protein (% total energy) 15% 18%
PUFA:Sat fat ratio 0.5 1.5
Cholesterol (mg) ≤300 150
Fibre (g) 9 31

Minerals

   
Potassium (mg) 1700 4700
Magnesium (mg) 165 500
Calcium (mg) 450 1240
Salt (g) 7.5

Without salt restrictions: 7.5

With salt restrictions: ≤6

How the DASH diet changes food intakes

Table 2. Key food components of the DASH diet compared to usual US intakes1,7,14
  No. of daily servings
Food group US usual intakes DASH
Fruit and vegetables 3.6 8-10
Grains 8.2 (refined) 7.5 (whole)
Low-fat dairy 0.5 2.7
Nuts, seeds and legumes 0 0.7
Red meat and processed meat 1.5 0.5
Poultry 0.8 0.6
Fish 0.2 0.5
Fats and oils 5.8 2.5
Snacks (high in salt and sat fat) & foods/ beverages high in sugars 4.1 0.7
Compared to the usual US diet (similar to a Western diet), those on the DASH diet consumed (table 2): 
  • more than double the amount of fruit and vegetables
  • similar servings of carbohydrates, but these were mainly whole grains rather than the refined carbohydrates in the typical US diet
  • more dairy servings (mainly low fat)
  • two thirds fewer servings of red and processed meat: half a serving per day down from 1.5 servings
  • double the amount of fish
  • more plant protein rather than animal proteins
  • half the quantity of fats and oils, with a switch from saturated to unsaturated fats
  • less than one serving daily of snacks and sweetened products, down from four servings.

The evidence for DASH and blood pressure lowering

The first DASH study

The first study of the DASH diet was a randomised controlled study. It included 456 US adults with no history of CVD and with normal to mildly raised blood pressure (<160 mmHg systolic blood pressure (SBP) and 80-95 mmHg diastolic blood pressure (DBP)). They were randomised to three different diets which they followed for eight weeks1:

  1. One group ate their usual North American diet (control group).
  2. One group followed the DASH diet, without sodium restrictions.
  3. One group was advised to increase their fruit and vegetable intake to at least 5-a-day in place of high saturated fat, salt and/or sugary foods (F&V-HFSS), thus HFSS foods were significantly reduced.

After eight weeks, both the DASH diet and the F&V-HFSS groups had significantly reduced blood pressure compared to the control group. The DASH diet reduced blood pressure the most7:

  • DASH diet vs control: SBP -5.5 mmHg & DBP -3.0 mmHg
  • F&V-HFSS vs control: SBP -2.7 mmHg & DBP -1.9 mmHg

Sodium intakes were similar across all three diets. This study highlighted that displacing HFSS foods with higher intakes of fruit and vegetables alone can bring about modest but significant reductions in blood pressure. The DASH diet resulted in significantly greater reductions, demonstrating that all the components of the DASH diet have a greater effect on blood pressure than just increasing fruit and vegetables.

In addition, the blood pressure-lowering effects were significantly greater in African Americans than Caucasians, and in those with higher baseline blood pressure levels.

The low salt DASH diet: bigger blood pressure reductions

A 1999 study investigated the impact of the DASH diet combined with salt restrictions2. The trial involved 412 American adults, with 50% being African American, randomly assigned to either the typical American diet or the DASH diet. Each diet had three levels of salt restrictions: 9g, 6g or 3g daily, each maintained for 30 days. The intervention lasted over 100 days including  wash-out periods in between the different salt intakes. 

Both the control and DASH groups had reduced blood pressure with salt reductions, however, the DASH arm had significantly greater reductions, showing the importance of other elements of the diet.

The most substantial difference in blood pressure reduction was seen between the usual American diet without salt restrictions and the DASH diet with salt restricted to 3g daily, the lowest salt group. Notably, individuals with higher baseline blood pressure and African Americans had the greatest benefits from the DASH diet intervention.

A 2023 re-analysis of the data showed that, compared to the typical American diet, the DASH diet reduced cardiac injury11 and resulted in a more than 10% reduction in the 10-year risk of atherosclerotic CVD (ASCVD)12.

Systematic reviews and meta-analyses

Systematic reviews and meta-analyses of randomised controlled trials confirm the blood pressure lowering effect of the DASH diet.

  • A 2015 meta-analysis of 20 RCTs demonstrated that, compared to the control diet (usual Western diet), DASH lowered SBP by 5.2mmHg and DBP by 2.6 mmHg (p<0.001)9.
  • A more recent meta-analysis of 54 RCTs compared the impact of the DASH diet on various metabolic outcomes4. The analysis reaffirmed DASH's blood pressure lowering effect. Compared to the control diet, DASH reduced SBP by 3.94mmHg and DBP by 2.44mmHg. The analysis also demonstrated greater reductions in body weight and waist circumference in the DASH diet group.

The evidence for lipid-lowering

The nutrient profile of the DASH diet is conducive to lowering blood lipids. Its emphasis on low saturated fat and higher unsaturated fat content has been firmly established to decrease LDL cholesterol levels15,16, which is now undisputed to be a causal factor in the development atherosclerotic CVD17,18.  Furthermore, the consumption of whole grains – particularly oats and barley19–21 – along with fruit and vegetables22–25, nuts26,27, and legumes28,29 have individually been shown to significantly improve blood lipid profiles.

  • One of the first DASH trials demonstrated that individuals following the DASH diet had significantly greater reductions in total and LDL cholesterol compared to the control group, -0.35mmol/L and -0.28mmol/L, respectively, p<0.000130.
  • A recent re-analysis of the original DASH data, involving 459 normotensive to mildly hypertensive adults without CVD, confirmed these findings12. After an eight-week intervention, participants randomised to the DASH diet group had a 0.34mmol/L greater reduction in total cholesterol than the control group (95% CI: -0.47, -0.2; p < 0.05) and a 10.3% lower risk of atherosclerotic CVD.
  • In a 2023 cross-sectional study, researchers examined the adherence to the DASH diet and its impact on cardiovascular risk factors among 2,831 Iranian overweight adults, averaging 41 years of age5. Those with higher adherence had significantly lower median total and LDL cholesterol levels compared to the lowest adherence.

Meta-analyses of RCTs re-affirm DASH's lipid lowering impact

  • A 2015 meta-analysis of 20 RCTs with 1,917 participants found that total and LDL cholesterol levels were 0.20mmol/L and 0.10mmol/L lower in the DASH diet group compared to the control group9.
  • An umbrella review of 31 RCTs also demonstrated that following the DASH diet lowered blood lipids.Total cholesterol fell by 0.20 mmol/L and LDL cholesterol fell by 0.10 mmol/L compared to the control group31.
  • A more recent meta-analysis of 54 RCTs confirmed earlier findings. Compared to the control group, individuals randomised to the DASH diet had significantly lower total and LDL cholesterol levels, -0.13 (p=0.008) and 0.08 mmol/L (p=0.04), respectively4.

The evidence for reduced CVD risk

Several cohort studies have investigated the impact of the DASH diet on CVD outcomes in the long-term10,31. A 2019 systematic review and meta-analysis of 15 prospective cohort studies, with over 900,000 participants in total, found that those consuming diets with the highest adherence to the DASH diet had a31:

  • 20% reduced risk of CVD
  • 21% reduced risk of CHD
  • 19% reduced risk of stroke
  • 18% reduced risk of diabetes.

A 2020 meta-analysis of 17 prospective cohort studies found that a stronger adherence to the DASH diet was linked to lower mortality rates from CVD, stroke and cancer10. Diets were scored for degree of adherence to the DASH diet with a score ranging from 8 (lowest adherence) to a maximum of 40 (highest adherence). The analysis demonstrated that every 5-point increase in adherence resulted in a:

  • 5% reduced risk of all-cause mortality
  • 3% lower risk of CVD and stroke mortality
  • 3% lower risk of stroke mortality.
Only studies with poor data collection and/or patient selection show no benefit of DASH

Two publications found no correlation between DASH and improved CVD outcomes5,32. One used data from a large Dutch cohort study whose primary aim was to investigate omega-3 supplementation on CVD events32. After a 12-year follow-up they found no correlation between adherence to the DASH diet and mortality from all causes or CVD. However, this study involved much older adults (60-80 years) with a history of CVD who were on lipid-lowering and blood pressure-lowering medication.

Another cohort study of 2,813 Iranian adults found no correlation between DASH adherence and blood pressure5. However, blood pressure results were available for less than 10% of the subjects and all had normal blood pressure ≤120 mmHg SBP and DBP ≤80.

In summary

Randomised controlled trials confirm that the DASH diet lowers high blood pressure and improves blood lipids, both established key metabolic risk factors for CVD. Cohort studies also show that diets closely aligned with the DASH diet reduce the risk of CVD mortality.

The DASH diet’s benefits have been attributed to the combined effects of its components: it is rich in fruits, vegetables, legumes, nuts and whole grains, coupled with low-fat dairy and limited red and processed meat, snacks and sugary foods. This results in a diet low in saturated fat and more unsaturated fats, and high in fibre, antioxidant vitamins and minerals (potassium, calcium and magnesium).  This nutrition profile is well established to lower both blood pressure and lipids.

References

  1. Sacks FM, Obarzanek E, Windhauser MM, et al. Rationale and design of the Dietary Approaches to Stop Hypertension trial (DASH): A multicenter controlled-feeding study of dietary patterns to lower blood pressure. Annals of Epidemiology. 1995;5(2):108-118. doi:10.1016/1047-2797(94)00055-X
  2. Svetkey LP, Sacks FM, Obarzanek E, et al. The DASH Diet, Sodium Intake and Blood Pressure Trial (DASH-Sodium): Rationale and Design. Journal of the American Dietetic Association. 1999;99(8):S96-S104. doi:10.1016/S0002-8223(99)00423-X
  3. IHME, Global Burden of Disease Collaborative Network. Global Burden of Disease Study 2019 (GBD 2019) Results. Institute for Health Metrics and Evaluation (IHME). Published 2020. https://vizhub.healthdata.org/gbd-results/
  4. Lari A, Sohouli MH, Fatahi S, et al. The effects of the Dietary Approaches to Stop Hypertension (DASH) diet on metabolic risk factors in patients with chronic disease: A systematic review and meta-analysis of randomized controlled trials. Nutrition, Metabolism and Cardiovascular Diseases. 2021;31(10):2766-2778. doi:10.1016/j.numecd.2021.05.030
  5. Shoaibinobarian N, Danehchin L, Mozafarinia M, et al. The Association between DASH Diet Adherence and Cardiovascular Risk Factors. Int J Prev Med. 2023;14:24. doi:10.4103/ijpvm.ijpvm_336_21
  6. Sahebkar A, Heidari Z, Kiani Z, et al. The Efficacy of Dietary Approaches to Stop Hypertension (DASH) Diet on Lipid Profile: A Systematic Review and Metaanalysis of Clinical Controlled Trials. Current Medicinal Chemistry. 2023;31:1-16.
  7. Appel LJ, Moore TJ, Obarzanek E, et al. A Clinical Trial of the Effects of Dietary Patterns on Blood Pressure. New England Journal of Medicine. 1997;336(16):1117-1124. doi:10.1056/NEJM199704173361601
  8. 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. New England Journal of Medicine. 2001;344(1):3-10. doi:10.1056/NEJM200101043440101
  9. 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. British Journal of Nutrition. 2015;113(1):1-15. doi:10.1017/S0007114514003341
  10. Soltani S, Arablou T, Jayedi A, Salehi-Abargouei A. Adherence to the dietary approaches to stop hypertension (DASH) diet in relation to all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective cohort studies. Nutrition Journal. 2020;19(1):37. doi:10.1186/s12937-020-00554-8
  11. Belanger MJ, Kovell LC, Turkson-Ocran RA, et al. Effects of the Dietary Approaches to Stop Hypertension Diet on Change in Cardiac Biomarkers Over Time: Results From the DASH-Sodium Trial. J Am Heart Assoc. 2023;12(2):e026684. doi:10.1161/JAHA.122.026684
  12. Jeong SY, Wee CC, Kovell LC, et al. Effects of Diet on 10-Year Atherosclerotic Cardiovascular Disease Risk (from the DASH Trial). American Journal of Cardiology. 2023;187:10-17. doi:10.1016/j.amjcard.2022.10.019
  13. BHF. Heart Statistics - UK CVD Fact Sheet. British Heart Foundation; 2024:21. Accessed February 14, 2024. https://www.bhf.org.uk/-/media/files/for-professionals/research/heart-statistics/bhf-cvd-statistics-uk-factsheet.pdf?rev=5c76af77f68e4c43b19f957890005bbe&hash=D31DB43089AAD361320212D15D4B70FB
  14. Conlin PR. The Dietary Approaches to Stop Hypertension (DASH) Clinical Trial Implications for Lifestyle Modifications in the Treatment of Hypertensive Patients. Cardiology in Review. 1999;7(5):284.
  15. Mensink RP, World Health Organization. Effects of Saturated Fatty Acids on Serum Lipids and Lipoproteins: A Systematic Review and Regression Analysis. World Health Organization; 2016. Accessed October 16, 2023. https://iris.who.int/handle/10665/246104
  16. SACN. Saturated fats and health. GOV.UK. Published August 2019. Accessed October 16, 2023. https://www.gov.uk/government/publications/saturated-fats-and-health-sacn-report
  17. Christensen JJ, Arnesen EK, Rundblad A, et al. Dietary fat quality, plasma atherogenic lipoproteins, and atherosclerotic cardiovascular disease: An overview of the rationale for dietary recommendations for fat intake. Atherosclerosis. 2024;389:117433. doi:10.1016/j.atherosclerosis.2023.117433
  18. Visseren FLJ, Mach F, Smulders YM, et al. 2021 ESC Guidelines on cardiovascular disease prevention in clinical practice: Developed by the Task Force for cardiovascular disease prevention in clinical practice with representatives of the European Society of Cardiology and 12 medical societies With the special contribution of the European Association of Preventive Cardiology (EAPC). European Heart Journal. 2021;42(34):3227-3337. doi:10.1093/eurheartj/ehab484
  19. Ho HVT, Sievenpiper JL, Zurbau A, et al. A systematic review and meta-analysis of randomized controlled trials of the effect of barley β-glucan on LDL-C, non-HDL-C and apoB for cardiovascular disease risk reductioni-iv. Eur J Clin Nutr. 2016;70(11):1239-1245. doi:10.1038/ejcn.2016.89
  20. Ho HVT, Sievenpiper JL, Zurbau A, et al. The effect of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for CVD risk reduction: a systematic review and meta-analysis of randomised-controlled trials. British Journal of Nutrition. 2016;116(8):1369-1382. doi:10.1017/S000711451600341X
  21. Public Health England. SACN Carbohydrates and Health Report. GOV.UK. Published 2015. Accessed December 15, 2023. https://www.gov.uk/government/publications/sacn-carbohydrates-and-health-report
  22. Mellendick K, Shanahan L, Wideman L, Calkins S, Keane S, Lovelady C. Diets Rich in Fruits and Vegetables Are Associated with Lower Cardiovascular Disease Risk in Adolescents. Nutrients. 2018;10(2):136. doi:10.3390/nu10020136
  23. Chung GKK, Yu RHY, Ho SSY, Woo J, Ho SC. Associations of consuming specific fruit and vegetable subgroups with LDL-C status in early postmenopausal Chinese women. Menopause. 2018;25(4):436-443. doi:10.1097/GME.0000000000001008
  24. Brouns F, Theuwissen E, Adam A, Bell M, Berger A, Mensink RP. Cholesterol-lowering properties of different pectin types in mildly hyper-cholesterolemic men and women. Eur J Clin Nutr. 2012;66(5):591-599. doi:10.1038/ejcn.2011.208
  25. Becerra-Tomás N, Paz-Graniel I, Tresserra-Rimbau A, et al. Fruit consumption and cardiometabolic risk in the PREDIMED-plus study: A cross-sectional analysis. Nutrition, Metabolism and Cardiovascular Diseases. 2021;31(6):1702-1713. doi:10.1016/j.numecd.2021.02.007
  26. Kim Y, Keogh J, Clifton PM. Nuts and Cardio-Metabolic Disease: A Review of Meta-Analyses. Nutrients. 2018;10(12):1935. doi:10.3390/nu10121935
  27. Del Gobbo LC, Falk MC, Feldman R, Lewis K, Mozaffarian D. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis, and dose-response of 61 controlled intervention trials 123. The American Journal of Clinical Nutrition. 2015;102(6):1347-1356. doi:10.3945/ajcn.115.110965
  28. Doma KM, Dolinar KF, Dan Ramdath D, Wolever TMS, Duncan AM. Canned Beans Decrease Serum Total and LDL Cholesterol in Adults with Elevated LDL Cholesterol in a 4-wk Multicenter, Randomized, Crossover Study. J Nutr. 2021;151(12):3701-3709. doi:10.1093/jn/nxab323
  29. Ha V, Sievenpiper JL, de Souza RJ, et al. Effect of dietary pulse intake on established therapeutic lipid targets for cardiovascular risk reduction: a systematic review and meta-analysis of randomized controlled trials. CMAJ. 2014;186(8):E252-262. doi:10.1503/cmaj.131727
  30. Obarzanek E, Sacks FM, Vollmer WM, et al. Effects on blood lipids of a blood pressure-lowering diet: the Dietary Approaches to Stop Hypertension (DASH) Trial. Am J Clin Nutr. 2001;74(1):80-89. doi:10.1093/ajcn/74.1.80
  31. 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):338. doi:10.3390/nu11020338
  32. Bonekamp NE, Cruijsen E, Visseren FL, Schouw YT van der, Geleijnse JM, Koopal C. Compliance with the DASH diet and risk of all-cause and cardiovascular mortality in patients with myocardial infarction. Clinical Nutrition. 2023;42(8):1418-1426. doi:10.1016/j.clnu.2023.06.033

 

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