DASH stands for Dietary Approaches to Stop Hypertension.
The DASH diet is designed to reduce blood pressure and improve blood lipids.
It’s typically low in fat and relatively high in carbs, but it’s not clear what role these macronutrients play in the diet’s effectiveness.
For this reason, a group of researchers compared the effects of a higher-fat, lower-carb DASH diet to the conventional DASH diet.
Their results were recently published in the American Journal of Clinical Nutrition.
The DASH diet focuses on fruits, vegetables, whole grains and lean meats.
The diet was designed after researchers noticed that high blood pressure was much less common in those who followed a plant-based diet, such as vegans and vegetarians, than in meat eaters (5, 6).
This led researchers to design a diet that provided liberal amounts of the nutrients that appeared to protect people against high blood pressure.
The result was the DASH diet, which is high in fruits and vegetables and contains some lean protein sources like chicken, fish and beans. The diet is low in red meat, salt, added sugars and fat.
It’s thought that one of the main reasons people with high blood pressure can benefit from this diet is because it reduces the amount of salt they’re eating.
The regular DASH diet program recommends that people eat no more than 2,300 mg of sodium per day (or 1 teaspoon), which is in line with most national guidelines.
The lower-salt version recommends that people eat no more than 1,500 mg of sodium per day (or 3/4 of a teaspoon).
Conclusion: The DASH diet was designed to reduce high blood pressure. It’s rich in fruits, vegetables and lean proteins, but it restricts red meat, salt, added sugars and fat.
Background
It is currently the world’s most popular diet aimed at lowering blood pressure and reducing the risk of heart disease.
The original DASH diet has the following characteristics (1, 2):
- High in fruits and vegetables.
- High in whole grains and fiber.
- Includes nuts, seeds and legumes several times weekly.
- High in low-fat dairy products.
- Relatively low in red meat, poultry and fish.
- Low in saturated fat, cholesterol and sodium.
- Relatively high in potassium, magnesium and calcium.
- Relatively low in refined sugar.
A large, observational study, called the Nurses’ Health Study, found a DASH-type diet to be associated with a reduced risk of heart disease and stroke (3).
Some researchers believe that the DASH diet may reduce heart disease risk because of its low saturated fat content (4, 5).
The DASH Diet Lowers Blood Pressure
Blood pressure is a measure of the force put on your blood vessels and organs as your blood passes through them. It’s counted in two numbers:
- Systolic pressure: The pressure in your blood vessels when your heart beats.
- Diastolic pressure: The pressure in your blood vessels between heartbeats, when your heart is at rest.
Normal blood pressure for adults is a systolic pressure below 120 mmHg and a diastolic pressure below 80 mmHg. This is normally written with the systolic pressure written above the diastolic pressure, like this: 120/80.
People with a blood pressure reading of 140/90 are considered to have high blood pressure.
Interestingly, the DASH diet has been shown to lower blood pressure in both healthy people and those who already have high blood pressure.
Furthermore, it achieved this even though people didn’t lose weight or restrict their salt intake (7, 8).
However, when sodium intake was restricted, they found that the DASH diet lowered blood pressure even further. In fact, the greatest reductions in blood pressure were seen in people with the lowest intakes of salt (9).
These low-salt DASH diet results were most impressive in people who already had high blood pressure, reducing it by an average of 11 points. In people with normal blood pressure, it reduced blood pressure by three points (5).
This is in line with other studies that have found that restricting salt intake can reduce blood pressure, especially in those who have high blood pressure (10).
However, it’s important to note that a decrease in blood pressure does not always translate to a decreased risk of heart disease or death (11).
Conclusion: Following a DASH dietary pattern is effective at lowering blood pressure, especially in people who already have high blood pressure.
Can You Lose Weight on the DASH Diet?
The DASH diet has been shown to reduce blood pressure, regardless of whether people lose weight or not.
However, if you already have high blood pressure, chances are you have been advised to lose weight.
This is because the more you weigh, the higher your blood pressure is likely to be (12, 13, 14).
Additionally, losing weight has been shown to lower blood pressure (15, 16).
Some studies have shown that people can lose weight on the DASH diet (17, 18, 19).
However, those who have lost weight on the DASH diet have been in a controlled calorie deficit, meaning they were told to eat fewer calories than they were using.
Given that the DASH diet cuts out lots of high-fat, sugary foods, people may find that they automatically reduce their calorie intake and lose weight. Other people may have to consciously restrict their intake (20).
Either way, if you want to lose weight on the DASH diet, you’ll still need to reduce your calorie intake so you’re taking in fewer calories than you are using up.
Conclusion: The DASH diet could help you lose weight. However, for weight loss to occur, you still have to make sure you’re eating fewer calories than you’re burning.
Other Potential Health Benefits
It’s well documented that the DASH diet can help lower blood pressure. However, the diet has additional benefits.
Here are some recorded benefits of the DASH diet:
- Decreases cancer risk: A recent review found that people following the DASH diet had a lower risk of some cancers, including colorectal and breast cancer (21).
- Lowers metabolic syndrome risk: Some studies have shown that the DASH diet reduces your risk of developing metabolic syndrome by up to 81% (22, 23).
- Lowers diabetes risk: Following the DASH diet has been linked to a lower risk of developing type 2 diabetes. Some studies have also shown that it can improve insulin resistance (24, 25).
- Decreases heart disease risk: One recent review showed that in women, following a DASH-like diet was associated with a 20% lower risk of heart disease and a 29% lower risk of stroke (26).
Many of these protective effects have been attributed to the high fruit and vegetable content of the DASH diet. This is because, in general, eating more fruits and vegetables is linked to a reduced risk of disease (27, 28, 29, 30).
Conclusion: A DASH dietary pattern could reduce your risk of some cancers, diabetes, heart disease and metabolic syndrome.
Does the DASH Diet Work for Everyone?
One of the key findings of DASH diet studies was that the greatest reductions in blood pressure were seen in those with the lowest intakes of salt.
While this is interesting, the benefits of salt restriction on health and lifespan are not clear cut. For people with high blood pressure, reducing salt intake has been shown to significantly affect blood pressure (6).
However, in people who have normal blood pressure, the effects of reducing salt intake are much smaller (10).
This could partly be explained by the theory that some people are “salt sensitive,” meaning some people are more sensitive to salt and that it has a greater effect on their blood pressure (31).
Conclusion: Lowering salt intake from very high levels is beneficial for most people. Further salt restriction, as advised on the DASH diet, may only be beneficial for people who are “salt sensitive” and have high blood pressure.
Article Reviewed
A team of scientists from the Children’s Hospital Oakland Research Institute, in California, compared the effects of the standard DASH diet and a higher-fat, lower-carb DASH diet on blood pressure and blood lipids.
Basic Study Design
This randomized, controlled trial examined the effects of a modified DASH diet and the standard DASH diet on blood pressure and blood lipids. The modified diet included more dairy fat and fewer carbs.
The participants were healthy men and women with systolic blood pressure less than 160 mm Hg, and diastolic blood pressure between 80 and 95 mm Hg.
The participants were assigned to three groups in random order:
- Standard DASH diet: Participants followed the conventional DASH diet.
- Higher-fat DASH diet: This diet included more dairy fat and less carbs, but was otherwise identical to the standard DASH diet.
- Control diet: The control diet was designed to represent a normal Western diet.
In the higher-fat DASH diet, the saturated fat content was increased from 8% to 14% of daily calories. To keep the calorie content the same, the carb content was also reduced by 12% of daily calories.
Each of these diets lasted for 3 weeks. The study had a crossover design, meaning that all of the participants followed all three diets during different study periods, separated by a 2-week washout period.
At the beginning and end of each of the three diets, the researchers measured blood pressure, blood lipids, body weight and body fat.
A total of 36 participants completed the study.
Conclusion: This randomized, crossover trial examined the effects of a higher-fat, lower-carb DASH diet on blood pressure and blood lipids.
Finding 1: Dairy Fat Did Not Adversely Affect Blood Pressure
Both the standard DASH diet and the higher-fat DASH diet reduced blood pressure to a similar extent, compared to the control diet, as shown in the chart below.
However, blood pressure was significantly lower two weeks after the participants had finished the higher-fat DASH diet, suggesting delayed effects.
This means that eating more saturated dairy fat on the DASH diet does not adversely affect blood pressure.
Other studies have found that modifying the standard DASH diet by replacing carbs with unsaturated fat or protein yields similar or greater improvements in blood pressure (6, 7, 8).
Conclusion: The standard DASH diet and the higher-fat DASH diet reduced blood pressure to a similar extent, compared to the control diet.
Finding 2: Higher-Fat DASH Diet Reduced Triglycerides
The DASH diet and the higher-fat DASH diet had different effects on the blood lipid profile. The higher-fat DASH diet reduced the levels of triglycerides, as shown in the chart below.
This modest reduction in triglycerides may be explained by the lower amounts of carbs in the higher-fat DASH diet, compared to the standard DASH diet (9).
Conclusion: The higher-fat DASH diet reduced triglycerides, compared to the standard DASH diet, due to the lower carb content of the higher-fat diet.
Finding 3: Effects on LDL Peak Diameter
High levels of small, low-density lipoproteins (LDL) have been associated with an increased risk of heart disease (10).
In the present study, the conventional DASH diet reduced the peak diameter of the LDL particles, but the higher-fat DASH diet increased the peak diameter, compared to the control diet.
This means that the higher-fat DASH diet may have caused a modest increase in LDL particle size.
In fact, there was a trend for higher levels of large LDL particles with the higher-fat DASH diet, but the findings were not significant.
Previous studies have shown that reduced carb and sugar intake may cause a shift from smaller to larger LDL particles, explaining the present findings (11, 12).
Conclusion: The higher-fat DASH diet increased LDL peak diameter, whereas the standard DASH reduced the LDL peak diameter. Large LDL size has been associated with a reduced risk of heart disease.
Finding 4: No Increase in LDL-Cholesterol
The higher-fat DASH diet did not increase levels of LDL-cholesterol, compared to the standard DASH diet.
This is inconsistent with studies showing that replacing carbs or unsaturated fats with saturated fats increases LDL-cholesterol (9, 13).
The authors speculate that the DASH diet may have characteristics that prevent the rise in LDL-cholesterol typically associated with a higher intake of saturated fats.
Conclusion: The higher-fat DASH diet did not increase LDL-cholesterol, compared to the standard DASH.
Limitations
This study appears to have been designed and implemented well.
It was a crossover trial, meaning that all participants were on all three diets during different study periods, separated by a 2-week washout period.
The purpose of the washout period was to prevent the previous diet from affecting the results of the next diet.
This washout, however, doesn’t appear to have worked in all cases, since there were some prolonged effects of the higher-fat DASH diet on blood pressure. The reason for this is unexplained.
Other limitations include a small number of participants and a relatively short study period.
Conclusion: This study did not have any serious limitations. However, the 2-week washout period between diets may not have been long enough with respect to blood pressure.
How to Make Your Diet More DASH-Like
Because there are no set foods on the DASH diet, 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.
Outside of measured fresh fruit juice portions, this diet recommends you stick to low-calorie drinks like water, tea and coffee.
Conclusion: It’s possible to adapt your current diet to align with the DASH diet. Simply eat more fruits and vegetables, choose low-fat products and lean proteins and limit your intake of processed, high-fat and sugary foods.
Frequently Asked Questions
If you’re thinking about trying the DASH approach for your blood pressure, then you might have a few questions about other aspects of your lifestyle.
The most commonly asked questions are addressed below.
Can I Drink Coffee on the DASH Diet?
The DASH diet doesn’t prescribe specific guidelines for coffee. However, some people worry that caffeinated beverages like coffee may increase their blood pressure.
It’s well known that caffeine can cause a short-term increase in blood pressure (33).
Furthermore, this rise is greater in people with high blood pressure (34, 35).
However, a recent review found that despite coffee causing a short-term (1–3 hours) increase in blood pressure, it didn’t increase the long-term risk of high blood pressure or heart disease (33).
For most healthy people with normal blood pressure, 3–4 regular coffees per day are considered safe (36).
However, the slight rise in blood pressure (5–10 mm Hg) caused by caffeine means that people who already have high blood pressure probably need to be more careful with their coffee consumption.
Do I Need to Exercise on the DASH Diet?
The DASH diet has been shown to be even more effective at lowering blood pressure when people are also active (18).
Given the independent benefits of exercise on health, this is not surprising.
It’s recommended to do 30 minutes of moderate activity most days, and it’s important to choose something you enjoy, as you will be more likely to keep it up.
Examples of moderate activity include:
- Walking (15 min/mile)
- Running (10 min/mile)
- Cycling (6 min/mile)
- Swimming laps (20 mins)
- Housework (60 mins)
Can I Drink Alcohol on the DASH Diet?
Drinking too much alcohol can increase your blood pressure (37).
In fact, regularly drinking more than three drinks per day has been linked to an increased risk of high blood pressure and heart disease (38).
On the DASH diet, it’s recommended that you drink alcohol sparingly and don’t exceed the national government guidelines — two or fewer drinks per day for men and one or fewer drinks per day for women.
: You can drink coffee and alcohol in moderation on the DASH diet. Combining the DASH diet with exercise may make it even more effective.
Summary and Real-Life Application
In short, this study shows that eating slightly more saturated dairy fat while on the DASH diet does not affect its beneficial effects on blood pressure.
Also, it did not have any adverse effects on the blood lipid profile.
A lower-carb, higher-fat DASH diet is a healthy, equally effective option, which may be easier to follow than the standard DASH diet.
For some people, the DASH diet may be easy to stick to and an effective way to reduce blood pressure.
However, it’s worth noting that reducing salt intake to 1,500 mg or less has not been linked to any hard health benefits, such as a reduced risk of heart disease or death, despite the fact that it can lower blood pressure.
Moreover, the DASH diet is very similar to the standard low-fat diet, which large controlled trials have not shown to reduce the risk of death (39, 40).
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