The DASH Diet And Why It Works

Foods that would be ideal for the DASH diet.
Image by Steve Buissinne, c/o Pixabay.

The DASH Diet is an acronym meaning ‘Dietary approaches to stop hypertension’. It was originally devised to prevent or treat high blood pressure. It is a diet promoted and endorsed by the National Heart, Lung, and Blood Institute (NHLBI). The US Department of Health and Human Services has issued an extremely useful guide for lowering blood pressure which includes plenty of information about this diet.

What Is This Diet?

The idea of the diet is to prevent or at least stop the development of high blood pressure (hypertension). It is still being extensively researched and has been identified as a key diet for preventing hypertension (high blood pressure) (Bazzano et al., 2013). It also appears to benefit in other areas too. It can help those with diabetes, with reducing depression and even reduce the risk of developing hearing loss.

The premise is very simple. It recommends us eating fruit and vegetables, various low-fat dairy foods but foods high in saturated fat is reduced and it is essential to limit your intake of salt.

A Diet For Reducing Blood Pressure

Blood pressure is an important aspect of our health especially our cardiovascular health. In the USA the American Heart Association estimated that 103 million adults in the USA have high blood pressure.

Blood pressure is a measure of the force placed on both blood vessels and organs as blood passes through them. There are two key numbers to think of:

The systolic pressure: the pressure in your blood vessels when the heart is beating

The diastolic pressure: the pressure in the blood vessels when the heart is at rest and between heartbeats.

The normal blood pressure for any healthy adult is a systolic pressure measured below 120 mmHg with a diastolic pressure below 80 mgHg. On your medical charts it is written as 120/80. If you have a blood pressure reading or 140/90 then you are considered to have high blood pressure although we can often suffer white coat syndrome which raises the blood pressure to these values.

There is plenty of evidence being acquired which demonstrates that the DASH diet can reduce blood pressure in healthy people but particularly in those with high blood pressure. The diet has been tested against other diets in plenty of randomized controlled trials in specific populations.

If you have normal blood pressure the systolic blood pressure drops by 4 mmHg and the diastolic pressure by 2 mmHg (Sacks et al., 1999).

It also works for people when they actually do not lose weight or start reducing or restricting their salt intake (Appel et al., 1997; Bray et al., 2004; Saneei et al., 2014).  It works even better in reducing blood pressure when the sodium intake is restricted too.

The diet works well with those who suffer from type 2 diabetes 

What Does The DASH Diet Involve?

The types of food suggested have always been those that dieticians and clinicians would recommend. These are foods full of fruits and vegetables, various whole grains, nuts, some lean protein coming from chicken and fish, and low-fat dairy. All the foods selected are meant to be high in those nutritional factors which help reduce blood pressure such as calcium, potassium, fiber and protein.

The DASH plan is well structured. The meal plan includes three whole-grain products on a daily basis, four to six servings of fruit, two to four servings of dairy products. It also suggests seeds, nuts, legumes and lean meat can be a part of the diet.

The National Heart, Lung, and Blood Institute which is part of the National Institutes of Health have produced a guideline based on a 2,000 calorie per day. This diet is described in the Harvard Health Publishing blog:

Food group Daily servings Examples of one serving
Whole grains 6–8 1 slice bread; 1/2 cup cooked rice; pasta; 1 ounce dry cereal
Vegetables 4–5 1 cup raw, leafy vegetables; 1/2 cup cooked vegetable
Fruit 4–5 1 medium apple; 1 cup melon
Low-fat/fat-free dairy 2–3 1 cup milk or yogurt; 1 1/2 ounces cheese
Lean meat, poultry, fish 6 or less 1 ounce cooked lean meat, fish, poultry; 1 egg
Nuts, legumes, seeds 4–5 per week 1/3 cup nuts; 2 tablespoons peanut butter; 1/2 cup cooked legumes
Fats and oils 2–3 1 teaspoon healthy oil (olive); 2 tablespoons salad dressing
Sweets 5 or less per week 1 tablespoon sugar; 1 cup soda; 1/2 cup sorbet
Adapted from the National Heart, Lung, and Blood Institute, National Institutes of Health

What is not encouraged in the DASH diet ?

Any foods high in saturated fat, so fatty meats, red meat (I guess), the full-fat dairy foods, tropical oils including coconut oil, all the beverages and confectionary full of sugar.

The sodium content is capped at 2.3 grams every day and then reduced to 1.5 grams. Sodium is a mineral which helps with water retention and in so doing will elevate blood pressure. Potassium generally will reverse the effect.

Potassium rich foods include avocados, bananas, white beans, black beans, orange juice, watermelon juice, edamame, beets, sweet potatoes  and canned salmon without added sodium.

One of the reasons the diet works is because it provides for a balanced diet and is sustainable over the long-term. The diet compares favourably with many others especially the Okinawan diet and the Mediterranean Diet.

Ranking Of The DASH Diet Versus The Rest 

The US News and World Report has been ranking it either at number 1 or 2 in the overall charts. It trumps the Mediterranean diet which is widely regarded throughout the world. Up to 2018 it had been the number one diet for eight consecutive years. It is one of the best for healthy eating and for heart health in particular.

A number of studies have shown it to be good for lowering blood pressure, and reducing what we would call bad cholesterol which is usually LDL. It also seems to be a good one for reducing body weight but over the long term.

Reduction Of Depression using The DASH Diet

Following the diet according to medical research is said to reduce depression later in life. The study was published in April 2018 and presented at the American Academy of Neurology’s 70th Annual Meeting in the same month. The study found that the odds of becoming depressed over time dropped by 11 per cent amongst those adults who were following the DASH diet plan. 

The lead author Laurel Cherian, MD, of Rush University Medical Center in Chicago stated in a press release:-

“Depression is common in older adults and more frequent in people with memory problems, vascular risk factors such as high blood pressure or high cholesterol, or people who have had a stroke.”

“Making a lifestyle change such as changing your diet is often preferred over taking medications, so we wanted to see if diet could be an effective way to reduce the risk of depression.”

The study examined 1,000 adults with an average age of 81. They were followed for and average of 6.5 years. They were assessed for depression. Each participant completed an annual survey on their diet. The type of diet was compared to the DASH diet, Mediterranean diet and traditional Western diets. The traditional Western diet is usually high in saturated fats and red meat but low in vegetables and fruits. This diet was the worst in the study for those who were most likely to develop depression.

The DASH Diet Might Reduce Hearing Loss

Hearing loss is an issue for the elderly in particular but dieting can help reduce that risk. 

Researchers at Brigham and Women’s Hospital in Boston, Massachussets, USA measured the hearing of  middle-aged and senior women in various U.S. test sites over a three year period (Curhan et al., 2019). These scientists also looked at 20 years of dietary data to understand how closely the participant’s diets followed three well-known types of diet. The three diets looked at were the Dietary Approaches to Stop Hypertension (DASH) diet, the Alternate Mediterranean diet, and the Alternate Healthy Index-2010.

It appears that those women who followed any of these diets or a mix of them has a 30% lower risk of decline in mid-frequency hearing sensitivity compared to those women who did not follow these diets. Here, the DASH diet showed positive benefits in this regard.

The lead author, Sharon Curhan, M.D. stated:

“The benefits of adherence to healthful dietary patterns have been associated with numerous positive health outcomes and eating a healthy diet may also help reduce the risk of hearing loss.”

Products

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There are plenty of books out there which cover the DASH diet as well some which do combinations of DASH with the Mediterranean diet. All of them tend to focus on recipes although one or two include a diet plan.

One of them is the ‘Dash Diet Cookbook For Beginners: the Complete Diet Guide With 500 Delicious And Simple Recipes‘. It has plenty of useful recipes. Another that we can recommend because it is up to date is: ‘The Big Dash Diet Cookbook for Beginners: Low Sodium Recipes and 4 Weeks meal Plan to Improve Your Health‘. There is even a a version called DASH Diet for Dummies which contains a 14-day diet meal plan for weight loss as well as being healthy.

References

Appel, L. J., Moore, T. J., Obarzanek, E., Vollmer, W. M., Svetkey, L. P., Sacks, F. M., … & Lin, P. H. (1997). A clinical trial of the effects of dietary patterns on blood pressure. New England Journal of Medicine336(16), pp. 1117-1124 (Article)

Azadbakht L, Fard NR, Karimi M, Baghaei MH, Surkan PJ, Rahimi M, et al. (2011) Effects of the Dietary Approaches to Stop Hypertension (DASH) eating plan on cardiovascular risks among type 2 diabetic patients: a randomized crossover clinical trial. Diabetes Care. 34(1) pp. 55–7. doi: 10.2337/dc10-0676 (Article)

Bazzano, L. A., Green, T., Harrison, T. N., & Reynolds, K. (2013). Dietary approaches to prevent hypertension. Current Hypertension Reports15(6), pp. 694-702 (Article)

Curhan, S. G., Halpin, C., Wang, M., Eavey, R. D., & Curhan, G. C. (2019). Prospective Study of Dietary Patterns and Hearing Threshold Decline. American Journal of Epidemiology. (Article)

Svetkey, L. P., Sacks, F. M., Obarzanek, E. V. A., Vollmer, W. M., Appel, L. J., Lin, P. H., … & Proschan, M. A. (1999). The DASH diet, sodium intake and blood pressure trial (DASH-sodium): rationale and design. Journal of the American Dietetic Association99(8), S96-S104 (Article)

Sacks, F. M., Moore, T. J., Appel, L. J., Obarzanek, E., Cutler, J. A., Vollmer, W. M., … & Bray, G. A. (1999). A dietary approach to prevent hypertension: a review of the Dietary Approaches to Stop Hypertension (DASH) Study. Clinical Cardiology22(S3), pp. 6-10 (Article)

Saneei, P., Salehi-Abargouei, A., Esmaillzadeh, A., & Azadbakht, L. (2014). Influence of Dietary Approaches to Stop Hypertension (DASH) diet on blood pressure: a systematic review and meta-analysis on randomized controlled trials. Nutrition, Metabolism and Cardiovascular Diseases, 24(12), pp. 1253-1261 (Article)

Revised: 5th August 2022. Updated references, added extra sections on the diet and removed old links to books.

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