The DASH diet plan, which scientists originally designed to lower blood pressure, is a healthy eating plan that emphasises vegetables, fruits, whole grains, legumes, lean meats, especially poultry, fish, nuts and seeds. It limits saturated fats, salt and processed foods such as sweets.
High blood pressure (hypertension) is the main risk factor for cardiovascular disease (CVD), the leading cause of premature death worldwide.
While hypertension rates are reducing in developed countries, they are increasing rapidly in developing countries. We now know that the key to reducing hypertension rates is regular exercise and a healthy diet, such as the dietary approaches to stop hypertension (DASH) diet.
Besides lowering blood pressure, health care professionals highly recommend the DASH plan because it also lowers blood glucose, triglycerides, low-density lipoprotein (LDL)-cholesterol and insulin resistance.
Before we take a closer look at what the DASH diet plan entails and how you can make its eating principles a part of your lifestyle, let’s cover explore
Hypertension and its prevalence
Did you know that approximately 54% of strokes and 47% of coronary heart diseases globally are due to hypertension (Wu et al., 2015)?
Shockingly, that is the case! But what exactly is hypertension?
According to the American Heart Association, hypertension is when blood pressure – the force of blood flowing through your blood vessels – is consistently too high. Clinically, hypertension is defined as blood pressure over 140/90 mmHg (Mills et al., 2020).
As of 2010, hypertension affected 31.1% of the world’s population (Mills et al., 2020). Recent data further shows that the number of people aged 30–79 years with hypertension in 2019 was double the number in 1990; 331 million women and 317 million men were affected in 1990 vs. 626 million women and 652 million men in 2019 (NCD Risk Factor Collaboration, 2021)
Hypertension seems to affect men slightly more frequently than women globally and is more prevalent in low- and middle-income countries than high-income countries (Mills et al., 2020). Hypertension rates also differ by race, affecting Black people, particularly women, more significantly than others (Lackland, 2014).
Notably, Blacks develop hypertension at an earlier age with a significantly higher risk of complications including stroke, end-stage kidney disease and heart failure than Whites (Lackland, 2014).
The Origins of the DASH Diet Plan
Scientists have always known that weight control, lower salt and alcohol intake and possibly higher potassium intakes could prevent or lower hypertension. They also knew that diets rich in fibre, potassium, magnesium, and calcium were linked to lower blood pressures.
However, when they gave hypertensive adults individual vitamin or mineral supplements, their blood pressure remained high. Interestingly, they found that vegetarians had lower blood pressures than non-vegetarians.
After critical evaluations, they realised that single nutrients had negligible blood-pressure-lowering effects. It was the combined effect of nutrients interacting together in a healthy diet that produced the blood pressure-lowering effect typically seen in people eating healthy vegetarian diets.
They then decide to investigate if healthy dietary patterns could lower blood pressure. And just like that, the DASH diet trial was born (Appel et al., 1997). Adults with hypertension who were not taking antihypertensive medication were enrolled.
The study was conducted in three phases: screening, run-in and intervention. The screening phase was designed to collect baseline blood pressure and other clinical data.
During the run-in phase, participants were fed a control (standard American) diet for three weeks, and during the last two weeks, their blood pressures were measured. After the run-in phase, the participants were randomised to continue either the control diet, a fruit and vegetable diet or a combination diet for eight weeks. Their blood pressures were measured before and during the last two weeks of the intervention phase.
All diets were prepared by the scientists and contained a similar amount of sodium – approximately three grams. However, there were differences in the composition and nutrient densities of the diets.
The fruit and vegetable diet contained more fruits and vegetables and fewer snacks and sweets than the control diet but was otherwise similar. Conversely, the combination diet was rich in fruits, vegetables and low-fat dairy foods with reduced saturated fat, total fat and cholesterol. The combination diet was also rich in potassium, magnesium, and calcium with high amounts of fibre and protein and low in sodium.
A total of 456 adults participated in the trial. The average age of the participants was 44; 66% were Black and 49% female.
Compared to the control diet, the combination diet reduced systolic and diastolic blood pressure by 5.5 mmHg and 3.0 mmHg more, respectively. The fruits and vegetable diet also reduced systolic and diastolic blood pressures more than the control diet.
Remarkably, the participants achieved these lower blood pressures within two weeks of starting the intervention diets and maintained them for the remaining six weeks of the intervention.
With such astonishing results, many dietary guidelines began and continue to recommend the DASH diet for preventing and resolving hypertension (Williams et al., 2018; Unger et al., 2020).
More Clinical Evidence for the DASH Diet Plan
Further studies have confirmed that the DASH diet can lower blood pressure, aid weight control and lower markers linked to CVD, such as low-density lipoprotein (LDL) cholesterol and HbA1c.
A 2005 study compared the DASH diet and a low-fat diet in 54 men with slightly elevated blood pressure. After 12 weeks, men in the DASH group reduced their weight and blood pressures significantly more than those in the low-fat group (Nowson et al., 2005).
A 2019 umbrella review of 15 meta-analysis and systematic review studies including 942, 140 participants found that the DASH diet effectively reduced blood pressure, body weight and HbA1c levels (Chiavaroli et al., 2019).
A 2020 systematic review and meta-analysis of randomised controlled trials also showed that the DASH diet reduced systolic and diastolic blood pressure by 4.2 mmHg and 2.5 mmHg more than a control diet (Filippou et al., 2020).
However, the DASH diet has produced inconsistent results in different races. Although the DASH diet improved diet quality in African Americans after 12 weeks, it had no significant effect on blood pressure (Whitt-Glover et al., 2010). In Chinese Canadians, the DASH diet significantly reduced both systolic and diastolic blood pressure (Zou, Dennis, and Parry, 2017). After ten weeks, it also significantly lowered systolic and diastolic blood pressure and LDL-cholesterol and increased blood potassium and vitamin C levels in a Korean cohort (Kim et al., 2013).
What can you eat, and should you limit on the DASH diet?
Unlike some restrictive diets, the DASH diet can work for most people. You can eat a diverse range of foods and modify the plan as you wish to fit your dietary preferences. Overall, the DASH diet encourages eating vegetables, fruits, legumes, whole grains, lean meats, fish, and low-fat dairy products. It also requires a low sodium intake – approximately 1500mg/day and minimal consumption of saturated fat and processed foods such as sugary beverages, baked goods, and sweets. Alcohol should be consumed sparingly.
An average person following the DASH diet should aim for the following per day:
| Type of Food | Number of servings | Example serving sizes |
| Vegetables e.g., spinach, kale, broccoli | 4-5 per day | 1 cup cooked vegetables |
| Grains e.g., rice, millet, oats | 6-8 per day | ½ cup cooked rice |
| Fruits e.g. oranges, blueberries, melon, apples | 4-5 per day | 1 medium apple |
| Low-fat dairy e.g., cottage cheese, low-fat cheddar | 2-3 per day | 1 cup milk |
| Lean meats, fish, poultry e.g. chicken breast, salmon, lean beef | 2 or fewer per day | 3-4 ounces cooked |
| Nuts, seeds e.g. sunflower seeds, almonds, cashew, pumpkin seeds | 4-5 per week | 2 tablespoons seeds |
| Fats and oils e.g. olive oil, avocado | 3-4 per day | 2 tablespoons salad dressing |
| High-fat/high-sugar foods | 5 or fewer per week | 1-ounce dark chocolate |
Please note, however, that the exact portions you need depend on your age, lifestyle, physical activity, weight, and gender. Work with a registered nutritionist or dietitian to determine the correct recommendations for you.
So, there you have it! Everything you need to know about the DASH diet and how it can help you lower your blood pressure, weight, LDL-cholesterol levels and HbA1c.
Like all healthy eating plans, you need to follow the DASH plan consistently to get and maintain results. And the only way to achieve this is to commit to changing your eating habits permanently.
I agree that changing your eating habits is challenging! But the great news is that it can be done!
You only need to decide and commit to changing. And once you do, the results you desire will be yours.
On that note, there’s no better time than right now.
Do it!
REFERENCES
- American Heart Association. The facts about high blood pressure. Available: https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure Last accessed: 01 October 2020.
- Wu, C-Y., Hu, H-Y., Chou, Y-J., Huang, N., Chou, Y-C., Li, C-P. (2015) High blood pressure and all-cause and cardiovascular disease mortalities in community-dwelling older adults. Medicine (Baltimore), 94(47): e2160.
- Mills, K.T., Stefanescu, A., He, J. (2020) The global epidemiology of hypertension. Nature Reviews Nephrology, 16: 223-237.
- NCD Risk Factor Collaboration (2021) Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants. The Lancet, 398(10304): 957–980.
- Appel, L.J., Moore, T.J., Obarzanek, E., Vollmer, W.M., Svetkey, L.P., Sacks, F.M., Bray, G.A., Vogt, T.M., Cutler, J.A., Windhauser, M.M., Lin, P-H., Karanja, N. (1997) A clinical trial of the effects of dietary patterns on blood pressure. New England Journal of Medicine, 336: 1117–24.
- Williams, B., Mancia, G., Spiering, W., Rosei, E.A., Azizi, M., Burnier, M., Clement, D.L., Coca, A., de Simone, G., Dominiczak, A., Kahan, T., Mahfoud, F., Rdeon, J., Ruilope, L., Zanchetti, A., Kerins, M., Kjeldsen, S.E., Kerutz, R., Laurent, S., Lip, G.Y.H., McManus, R., Narkiewicz, K., Ruschitzka, F., Schmieder, R.E., Shlyakhto, E., Tsioufis, C., Aboyans, V., Desormais, I. (2018) 2018 ESC/ESH Guidelines for the management of arterial hypertension: the task force for the management of arterial hypertension of the European Society of Cardiology and the European Society of Hypertension. Journal of Hypertension, 36(10): 1953–2041.
- Nowson, C.A., Worsley, A., Margerison, C., Jorna, M.K., Godfrey, S.J., Booth, A. (2005) Blood pressure change with weight loss is affected by diet type in men. American Journal of Clinical Nutrition, 81(5): 983–9.
- Chiavaroli, L., Viguilliouk, E., Nishi, S.K., Mejia, S.B., Rahelic, D., Kahleova, H., Salas-Salvado, J., Kendall, C.W.C., Sievenpiper, J.L. (2019) DASH dietary pattern and cardiometabolic outcomes: an umbrella review of systematic reviews and meta-analyses. Nutrients, 11(2): 338.
- Filippou, C.D., Tsioufis, C.P., Thomopoulos, C.G., Mihas, C.C., Dimitriadis, K.S., Sotiropoulou, L.I., Chrysochoou, C.A., Nihoyannopoulos, P.I., Tousoulis, D.M. (2020) Dietary approaches to stop hypertension (DASH) diet and blood pressure reduction in adults with and without hypertension: a systematic review and meta-analysis of randomised controlled trials. Advances in Nutrition, 11(5): 1150–1160.
- Unger, T., Borghi, C., Charchar, F., Khan, N.A., Poulter, N.R., Prabhakaran, D., Ramirez, A., Schlaich, M., Stergiou, G.S., Tomaszewski, M., Wainford, R.D., Williams, B., Schutte, A.E. (2020) 2020 International Society of Hypertension global hypertension practice guidelines. Journal of Hypertension, 38(6): 982–1004.
- Whitt-Glover, M.C., Hunger, J.C., Foy, C.G., Quandt, S.A., Vitolins, M.Z., Leng, I., Hornbuckle, L.M., Sanya, K.A., Bertoni, A.G. (2013) Translating the dietary approaches to stop hypertension (DASH) diet for use in under-resourced urban African American communities, 2010. Preventing Chronic Diseases, 10: 120088.
- Zou, P., Dennis, C-L., Lee, R., and Parry, M. (2017) Dietary approach to stop hypertension with sodium reduction for Chinese Canadians (DASHNa-CC): a pilot randomised controlled trial. The Journal of Nutrition, Health and Aging, 21(10): 1225–1232.
- Kim, H., Song, H-J., Han, H-R., Kim, K.B., Kim, M.T. (2013) Translation and validation of the dietary approaches to stop hypertension for Koreans intervention: culturally tailored dietary guidelines for Korean Americans with high blood pressure. The Journal of Cardiovascular Nursing, 28(6): 514–23.
- Guo, R., Li, N., Yang, R., Liao, X-Y., Zhang, Y., Zhu, B-F., Zhang, Q., Chen, L.., Zhang, Y-G., Lei, Y. (2021) Effects of the modified DASH diet on adults with elevated blood pressure or hypertension: a systematic review and meta-analysis. Frontiers in Nutrition, https://doi.org/10.3389/fnut.2021.725020
