Hypertension and DASH Diet

Abstract 

Diet has been shown to play a major role in the development of hypertension (high blood pressure). This article introduces the DASH (Dietary Approaches to Stop Hypertension) diet, which was designed to combat high blood pressure and reduce people’s risk of heart disease.

What Is Hypertension?

Blood pressure or hypertension is a measure of the force exerted on your blood vessels and organs as your blood passes through them. It’s counted in two numbers:

• Systolic pressure: The pressure in blood vessels when the heart is in state of contraction.
• Diastolic pressure: The pressure in blood vessels in between contractions or when the heart is at rest.

Normal blood pressure for adults is a systolic pressure below 120 mmHg and a diastolic pressure below 80 mmHg, normally written as 120/80 mmHg. For individuals 40–70 years of age, each increment of 20 mm Hg in systolic BP or 10 mm Hg in diastolic BP doubles the risk of cardiovascular disease across the entire BP range from 115/75 to 185/115 mm Hg.

Hypertension is a major risk factor for,

• Atherosclerosis:the buildup of fats, cholesterol and other substances in and on your artery walls (plaque), which can restrict blood flow.
• Stroke:blood supply to part of your brain is interrupted or reduced, preventing brain tissue from getting oxygen and nutrients.
• Congestive heart failure:a chronic progressive condition that affects the pumping power of your heart muscles.
• Renal failure:a condition when your kidneys become unable to filter waste products from your blood.

What Are The Mechanisms Of Essential Hypertension?

• In the vast majority (90-95%) of cases hypertension results from complex interactions between multiple genetic and environmental influences.
• Genetic factors: contribute to blood pressure regulation, as shown by comparisons of monozygotic and dizygotic twins.
• Insufficient renal sodium excretion: may lead sequentially to an increase in fluid volume, increased cardiac output, and peripheral vasoconstriction, thereby elevating blood pressure.
• Environmental factors: such as obesity, stress, smoking, inadequate physical inactivity, and heavy salt consumption all are implicated in hypertension.

What Is DASH Diet?

The DASH diet (Dietary Approaches to Stop Hypertension) is a dietary pattern promoted by the United States based NHLBI(National Heart, Lung, and Blood Institute) to prevent and control hypertension. It can be regarded as a primordial level of prevention. The DASH diet is one of three healthy diets recommended in the 2015-2020 US Dietary Guidelines, which also include the Mediterranean diet or a vegetarian diet.

In January 2018, DASH was named the number 1 for "Best Diets Overall" for the eighth year in a row,and also as "For Healthy Eating", and "Best Heart-Healthy Diet"; and tied number 2 "For Diabetes"(out of 40 diets tested) in the U.S. News & World Report's annual “Best Diets” rankings.

• The DASH diet is rich in fruits, vegetables, whole grains, legumes, and low-fat dairy foods. 
• It includes lean meat, fish, poultry, nuts, and beans.
• It is limited in sugar-sweetened foods and beverages, red meat, and added fats.
• The regular DASH diet suggests no more than 1 teaspoon (2,300 mg) of sodium per day.
• The lower-salt version promotes intake of no more than 3/4 teaspoon (1,500 mg) of sodium per day.

What Are The Potential Benefits Of DASH Diet?

Lowers Blood Pressure: in both healthy people and hypertensive. 

• Low-salt DASH diet results are most impressive in people who already have high blood pressure, reducing systolic BP by an average of 12 mmHg and diastolic BP by 5 mmHg.
• In people with normal BP, it reduces systolic BP by 4 mmHg and diastolic by 2 mmHg (1).
• May Aid Weight Reduction: As the DASH diet cuts out a lot of high-fat, sugary foods, it automatically reduces their calorie intake and helps in weight loss (2).
• Decreases Cancer Risk:people following the DASH diet have a lower risk of certain cancers, including colorectal and breast cancer.
• Lowers risk of developing metabolic syndrome by up to 81% (3).
• Lowers risk of developing type 2 diabetes mellitus (4).
• Decreases risk of developing heart disease and stroke (5).

What to eat on a DASH diet?

The DASH diet recommends specific servings of various food categories. Below is an example mentioning food portions in a 2000-calorie diet.

Whole Grains: 6–8 Servings per Day

Examples of a serving include:

• 1 slice of multigrain bread
• 28 grams of dry, whole-grain cereal
• 95 grams of cooked brown rice, pasta or cereal

Vegetables: 4–5 Servings per Day

All vegetables are allowed on the DASH diet.Examples of a serving include:

• About 30 grams of raw, leafy dark green vegetables like spinach or kale
• About 45 grams of sliced vegetables (raw or cooked) like broccoli, carrots, or tomatoes.

Fruits: 4–5 Servings per Day

Examples of a serving include:

• 1 medium apple or pear
• About 50 grams of dried apricots
• About 30 grams of fresh, frozen or canned peaches

Dairy Products: 2–3 Servings per Day

Dairy products on the DASH diet should be low in fat. Examples include skim milk and low-fat cheese and yogurt.

Examples of a serving include:

• 240 ml of low-fat milk
• 1 cup (285 grams) of low-fat yogurt
• 1.5 ounces (45 grams) of low-fat cheese

Lean Chicken and Fish: 6 or Fewer Servings per Day

Examples of a serving include:

• 1 ounce of cooked chicken or fish
• 1 egg

Nuts, Seeds and Legumes: 4–5 Servings per Week

Examples of a serving include:

• 50 grams of nuts like almonds, peanuts, hazelnuts and walnuts
• 2 tablespoons (40 grams) of nut butter
• 2 tablespoons (16 grams) of seeds like sunflower seeds and flaxseeds.
• 1/2 cup (40 grams) of cooked legumes like kidney beans, lentils and split peas.

Fats and Oils: 2–3 Servings per Day

Examples of a serving include:

• 1 teaspoon (4.5 grams) of soft margarine
• 1 teaspoon (5 ml) of vegetable oil
• 1 tablespoon (15 grams) of low fat mayonnaise
• 2 tablespoons (30 ml) of light salad dressing

Candy and Added Sugars: 5 or Fewer Servings per Week

Added sugars are kept to a minimum on the DASH diet. Examples of a serving include:

• 1 tablespoon of sugar
• 1 tablespoon of jelly or jam
• 1 cup of lemonade

Take Home Points:

• The DASH diet may offer you an alternative to drug therapy if you are hypertensive and, as a population approach, may prevent hypertension.
• Combining the DASH diet with exercise may make it even more effective.
• It’s possible to align your current diet with the DASH diet by simply eating more fruits and vegetables, choosing low-fat products as well as lean proteins and limit your intake of processed, high-fat and sugary foods.

References:

• Sacks FM, Appel LJ, Moore TJ, Obarzanek E, Vollmer WM, Svetkey LP, et al. A dietary approach to prevent hypertension: a review of the Dietary Approaches to Stop Hypertension (DASH) Study. ClinCardiol. 1999;22(7):III6-10. 
• Blumenthal JA, Babyak MA, Hinderliter A, Watkins LL, Craighead L, Lin PH, Caccia C, et al. Effects of the DASH diet alone and in combination with exercise and weight loss on blood pressure and cardiovascular biomarkers in men and women with high blood pressure: the ENCORE study. Arch Intern Med. 2010;170(2):126-35.
• Saneei P, Fallahi E, Barak F, Ghasemifard N, Keshteli AH, Yazdannik AR, et al. Adherence to the DASH diet and prevalence of the metabolic syndrome among Iranian women. Eur J Nutr. 2015;54(3):421-8.
• Hinderliter AL, Babyak MA, Sherwood A, Blumenthal JA. The DASH diet and insulin sensitivity. CurrHypertens Rep. 2011;13(1):67-73.
• Salehi-Abargouei A, Maghsoudi Z, Shirani F, Azadbakht L. Effects of Dietary Approaches to Stop Hypertension (DASH)-style diet on fatal or nonfatal cardiovascular diseases--incidence: a systematic review and meta-analysis on observational prospective studies. Nutrition. 2013;29(4):611-8.

 

Author

Dr. Utkarsh Sharma

(MBBS, MD Pathology)