High blood pressure, or hypertension, is a prevalent health issue affecting nearly half the world's population. It significantly elevates the risk of severe conditions like heart disease, kidney failure, and stroke. The likelihood of developing hypertension increases with age, affecting over 60% of individuals over 60. Given the significant role diet plays in hypertension, the Dietary Approaches to Stop Hypertension (DASH) diet has been developed as a dietary strategy to help reduce it. This article delves into the DASH diet, examining its benefits and potential risks, especially when modified to be low-carb.
Understanding the DASH Diet
The DASH diet emerged from observations that individuals consuming plant-based diets, such as vegans and vegetarians, exhibited lower rates of high blood pressure. Consequently, the DASH diet emphasizes fruits, vegetables, and lean protein sources like chicken, fish, and beans. It is intentionally low in red meat, salt, added sugars, and fats. A key element of the DASH diet is limiting salt intake, ideally to no more than 3/4 teaspoon (1,500 mg) of sodium per day, as scientists believe this reduction significantly benefits individuals with high blood pressure.
The DASH diet is based on the following foods: fruits, vegetables, low fat milk, whole grains, fish, poultry, beans, and nuts. It recommends reducing sodium, foods and beverages with added sugars, and red meat. The diet is heart-friendly as it limits saturated and trans fat, while increasing the intake of potassium, magnesium, calcium, protein, and fiber, nutrients believed to help control blood pressure.
Adapting to DASH Guidelines
You can adapt your current diet to the DASH guidelines by doing the following:
- Eat more vegetables and fruits.
- Swap refined grains for whole grains.
- Choose fat-free or low fat dairy products.
- Choose lean protein sources like fish, poultry, and beans.
- Cook with vegetable oils.
- Limit your intake of foods high in added sugars, like soda and candy.
- Limit your intake of foods high in saturated fats like fatty meats, full-fat dairy, and oils like coconut and palm oil.
DASH Diet Serving Recommendations
The diet suggests a specific number of servings of the recommended foods listed above. The sample plans provided by the National Heart Lung and Blood Institute (NHLBI) are based on 1600, 2000, or 2600 calories daily. For 2000 calories a day, this translates to about 6-8 servings of grains or grain products (whole grains recommended), 4-5 servings vegetables, 4-5 fruits, 2-3 low fat dairy foods, 2 or fewer 3-ounce servings of meat, poultry, or fish, 2-3 servings of fats and oils, and 4-5 servings of nuts, seeds, or dry beans per week. It advises limiting sweets and added sugars to 5 servings or less per week.
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The number of servings you can eat depends on how many calories you consume. Below is an example of food portions based on a 2,000-calorie diet:
Whole grains: 6-8 servings per day
Examples of a serving include:
- 1 slice of whole-grain bread
- 1 ounce (oz) or 28 g of dry, whole-grain cereal
- 1/2 cup (95 g) of cooked rice, pasta or cereal
Vegetables: 4-5 servings per day
All vegetables are allowed on the DASH diet. Examples of a serving include:
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- 1 cup (about 30 g) of raw, leafy green vegetables like spinach or kale
- 1/2 cup (about 45 g) of sliced vegetables - raw or cooked - like broccoli, carrots, squash or tomatoes
Fruits: 4-5 servings per day
If you’re following the DASH approach, you’ll be eating a lot of fruit. Examples of fruits you can eat include apples, pears, peaches, berries, and tropical fruits like pineapple and mango.
Examples of a serving include:
- 1 medium apple
- 1/4 cup (50 g) of dried apricots
- 1/2 cup (30 g) 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, low-fat cheese, and yogurt.
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Examples of a serving include:
- 1 cup (240 ml) of low fat milk
- 1 cup (285 g) of low fat yogurt
- 1.5 oz (45 g) of low fat cheese
Lean chicken, meat, and fish: 6 or fewer servings per day
Choose lean cuts of meat and try to eat a serving of red meat only occasionally - no more than once or twice a week.
Examples of a serving include:
- 1 oz (28 g) of cooked meat, chicken or fish
- 1 egg
Nuts, Seeds, and Legumes: 4-5 Servings per Week
Examples of a serving include:
- 1/3 cup (50 g) of nuts
- 2 tbsp (40 g) of nut butter
- 2 tbsp (16 g) of seeds
- 1/2 cup (40 g) of cooked legumes
Fats and Oils: 2-3 Servings per Day
The DASH diet recommends vegetable oils over other oils. These include margarine and oils like canola, corn, olive, or safflower. It also recommends low fat mayonnaise and light salad dressing.
Examples of a serving include:
- 1 tsp (4.5 g) of soft margarine
- 1 tsp (5 milliliters (ml)) of vegetable oil
- 1 tsp (15 g) of mayonnaise
- 2 tsp (30 ml) of salad dressing
Candy and Added Sugars: 5 or Fewer Servings per Week
Added sugars are kept to a minimum on the DASH diet, so limit your intake of candy, soda, and table sugar. The DASH diet also restricts unrefined sugars and alternative sugar sources, like agave nectar.
Examples of a serving include:
- 1 tablespoon (tbsp) (12.5 g) of sugar
- 1 tbsp (20 g) of jelly or jam
- 1 cup (240 ml) of lemonade
Commonly Asked Questions About DASH Diet
- Are eggs ok to eat on a DASH diet? Yes, eggs are ok to eat on a DASH diet. Here is an example of a meal you might eat for breakfast that includes eggs: 2 boiled eggs, 2 slices of turkey bacon with 1/2 cup (38 g) of cherry tomatoes, 1/2 cup (80 g) of baked beans, and 2 slices of whole-wheat toast, plus 1/2 cup (120 ml) of fresh orange juice.
- Are potatoes ok to eat on a DASH diet? Yes, you can include potatoes in a DASH diet. For example, you might plan to eat one of the following: 3 oz (85 g) of salmon cooked in 1 tsp (5 ml) of vegetable oil with 1 cup (300 g) of boiled potatoes and 1.5 cups (225 g) of boiled vegetables; 6 oz (170 g) of cod fillet, 1 cup (200 g) of mashed potatoes, 1/2 cup (75 g) of green peas and 1/2 cup (75 g) of broccoli.
- Is peanut butter ok to eat on the DASH diet? Yes. For example, for breakfast, you might make 2 slices of whole-wheat toast with 2 tbsp (40 g) of peanut butter, 1 medium banana, 2 tbsp (16 g) of mixed seeds, and 1/2 cup (120 ml) of fresh orange juice.
Benefits of the DASH Diet
Beyond its primary goal of reducing blood pressure, the DASH diet offers a spectrum of potential health benefits:
- Blood Pressure Reduction: Numerous studies affirm the DASH diet's effectiveness in lowering blood pressure. A consistent body of research has found that DASH lowers blood pressure in people with high blood pressure but also normal blood pressure even without lowering sodium intake. It can produce greater reductions in blood pressure if sodium is restricted to less than 2300 mg a day, and even more so with a 1500 mg sodium restriction. [6, 7]
- Weight Loss: Research indicates that the DASH diet can aid in weight management. A 2020 study found that following DASH containing at least 126 grams (g) of lean protein helped older adults over 65 with obesity reduce body fat. A 2023 study also suggests DASH can be helpful in lowering belly fat.
- Cancer Risk Reduction: A 2019 review linked the DASH diet to a lower risk of certain cancers, including breast, hepatic, endometrial, and lung cancer. Similar results were found in a study looking at colorectal cancer and DASH.
- Metabolic Syndrome Risk Reduction: Research suggests that the DASH diet reduces the risk of metabolic syndrome by nearly 50%. Other research confirms there may be an inverse relationship between following DASH and the chance of developing metabolic syndrome.
- Diabetes Management: The diet has been linked to a lower chance of diabetes. Research also demonstrates that it may improve insulin resistance as well. Adherence to the DASH-style pattern may also help prevent the development of diabetes, as analyzed in a recent meta-analysis
- Heart Disease Prevention: A 2019 review found that following DASH may be linked to a lower chance of developing heart disease. Specifically, research suggests this diet may help lower various risk factors for heart disease, such as blood cholesterol, sugar, and fats. The DASH diet was found to lower cardiovascular risk in a controlled 8-week trial looking at participants randomized to consume either a DASH diet (low in total/saturated fat with whole grains, poultry, fish, nuts, fruits and vegetables), a fruit and vegetable-rich diet (more fruits/vegetables than control diet but same amount of fat), or control diet (standard American diet high in fat and cholesterol). [9] The researchers estimated a 10-year reduction in risk for cardiovascular disease based on the participants’ blood pressure and cholesterol levels before and after the diet intervention.
- Kidney Disease Prevention: Adherence to the DASH-style pattern may also help prevent the development of kidney disease as found in the Atherosclerosis Risk in Communities (ARIC) cohort that followed more than 3700 people who developed kidney disease. [11] Dietary components of DASH that were protective in the ARIC cohort included a high intake of nuts, legumes, and low-fat dairy products.
Many of these protective effects are attributed to the diet’s high fruit and vegetable content. In general, eating more fruits and vegetables can help reduce the chance of developing disease.
The Low-Carb DASH Diet: A Modified Approach
While the traditional DASH diet emphasizes whole grains, a modified version, the low-carb DASH diet, reduces carbohydrate intake while increasing protein or unsaturated fats. Eating less carbohydrate but more protein or unsaturated fats may also benefit the heart. The OmniHeart (Optimal Macronutrient Intake Trial to Prevent Heart Disease) clinical trial found that swapping out about 10% of calories from carbohydrates with protein (especially plant proteins like legumes, nuts, seeds) or monounsaturated fats (olive oil, canola oil, nuts, seeds) lowered blood pressure, LDL cholesterol, and triglycerides among adults with early or stage 1 hypertension. [4] Swapping carbohydrates specifically with unsaturated fats also helped to increase “good” HDL cholesterol. The benefit did not come from simply eating more fats and protein, but swapping an equal amount of calories so that the total calorie level stayed about the same.
A modified version of a diet known to lower blood pressure is also effective at lowering glucose in adults with type 2 diabetes, according to a clinical trial led by researchers at the Johns Hopkins Bloomberg School of Public Health. The study builds on the DASH diet-Dietary Approaches to Stop Hypertension-developed in the mid-1990s by an interdisciplinary team of researchers supported by National Institutes of Health funding to address high blood pressure in the general population. The DASH diet emphasizes fruits, vegetables, and low-fat dairy products, and is low in saturated fat and cholesterol. To understand the DASH diet’s impacts in patients with diabetes, a team led by Johns Hopkins researchers modified the diet for people with type 2 diabetes. The DASH for Diabetes-DASH4D-diet is similar to the DASH diet but lower in carbohydrates and higher in unsaturated fats. Participants’ blood glucose levels were measured using wearable continuous glucose monitoring (CGM) devices. The new study, named DASH4D CGM, found that when participants consumed the DASH4D diet, they had a clinically meaningful reduction of average blood glucose level and an increase in average time spent with blood glucose in the recommended range compared to when they consumed a standard diet. Participants eating the DASH4D diet had blood sugar levels that were on average 11 mg/dL lower than when eating the standard diet and stayed in the optimal blood glucose range for an extra 75 minutes a day. Both effects are considered clinically meaningful for people with diabetes, as they may lower risks of heart disease, kidney disease, and other long-term adverse consequences of diabetes.
Benefits of a Low-Carb DASH Diet
- Enhanced Blood Sugar Control: For individuals with type 2 diabetes, a low-carb DASH diet can lead to significant improvements in blood sugar control. The DASH4D CGM study found that participants on the DASH4D diet experienced a clinically meaningful reduction in average blood glucose levels and increased time spent within the recommended glucose range.
- Improved Cholesterol Levels: The OmniHeart trial demonstrated that replacing carbohydrates with protein or monounsaturated fats could lower LDL cholesterol and triglycerides while increasing HDL cholesterol.
- Weight Management: By reducing carbohydrate intake and increasing protein and healthy fats, the low-carb DASH diet can promote satiety and support weight loss efforts.
Potential Risks and Considerations
While the DASH diet is generally safe and beneficial, some considerations are worth noting:
- Sodium Restriction: While studies on the DASH diet determined that the greatest reductions in blood pressure occurred in those with the lowest salt intake, the benefits of salt restriction on health and lifespan are not clear-cut. The theory that some people are more salt sensitive - meaning that salt exerts a greater influence on their blood pressure - could partly explain this. One 2020 suggests that it’s unclear whether there are any benefits to reducing salt intake this low, and that the chance of heart disease begins to rise only after consuming more than 5,000 mg of sodium daily. For this reason, healthy individuals may have little reason to follow this diet. That said, this target can be achieved easily by reducing the amount of highly processed food in your diet and eating mostly whole foods.
- Dietary Planning: DASH requires each person to plan their own daily menus based on the allowed servings. The types of foods listed are not comprehensive. For example, avocados are not included so it is not clear if they would be categorized as a fruit or a fat serving. Certain foods are placed into questionable categories: pretzels are placed in the grain group even though they have fairly low nutrient content and no fiber; frozen yogurt is placed in the dairy group even though most brands contain little calcium and vitamin D and are high in added sugar.
- Digestive Issues: Some people may experience gas and bloating when starting the diet due to the high fiber content of plant foods like fruits, vegetables, and whole grains.
- Individual Needs: Effectiveness can vary among individuals. People with certain health conditions may need to modify the standard DASH diet.