The DASH Diet to lower high blood pressure

The Heart and Stroke Foundation has encouraged Canadians to eat a healthy diet, control salt intake, and be physically active to lower blood pressure. The latest results from the DASH study – Dietary Approaches to Stopping Hypertension – has confirmed these recommendations, providing more encouragement for people to choose a healthier diet. Research has shown that following a plan for healthy eating can reduce the risk of developing high blood pressure and lower already elevated blood pressure.

What are the DASH studies?
The DASH Diet is based on two studies, DASH and DASH-Sodium, that looked at ways of reducing blood pressure through changes in diet. In the DASH study, people were given one of three eating plans: a plan similar in nutrients to what most North Americans eat; the same plan but with extra vegetables and fruit; or the DASH diet, which is rich in vegetables, fruit and low-fat dairy foods and low in saturated fat, total fat and cholesterol.

The results were compelling. The diet higher in vegetables and fruit and the DASH diet both reduced blood pressure. The DASH diet had the greatest effect on blood pressure, lowering levels within two weeks of starting the plan. Not only was blood pressure reduced, but total cholesterol and low-density lipoprotein (LDL) or "bad cholesterol" were lower, too.

In the DASH-Sodium study, participants were given one of three sodium plans: the DASH diet with 3,300 mg of salt (sodium) per day (a normal amount for many North Americans); 2,400 mg of salt (a moderately restricted amount); or 1,500 mg of salt (a more restricted amount, about 2/3 of a teaspoon). Blood pressure was lower for everyone on the DASH diet. However, the less salt people consumed, the greater the decrease in blood pressure. People who already had high blood pressure had the largest decrease in blood pressure.

Why is a healthy blood pressure important?
High blood pressure causes the heart to work harder to pump nutrient- and oxygen-rich blood to the body. The arteries that deliver the blood become scarred and less elastic. Although these changes happen to everyone as they age, they happen more quickly in people with high blood pressure. As the arteries stiffen, the heart has to work even harder, causing the heart muscle to become thicker, weaker and less able to pump blood. When high blood pressure damages arteries, they are not able to deliver enough blood to organs for their proper functioning. As a result, organs may become damaged, too. For example, this type of damage can affect the heart, causing a heart attack, the brain, causing a stroke, and the kidneys, leading to kidney failure.

How is DASH different from Canadian recommendations?
The DASH diet isn’t unique – it is very similar to Canada’s Food Guide produced by Health Canada and endorsed by the Heart and Stroke Foundation. The table below shows how similar the two diets are.

Canada’s Food Guide has a greater range in the number of servings than the DASH diet, which also recommends a higher level of vegetable and fruit intake.

 

 

Canada's Food Guide servings per day

Canada’s Food Guide recommendations

DASH servings per day

Vegetables and fruit

 

Females (age 19-50) 7-8
Males (age 19-50)   8-10
Females (age 51+)  7
Males (age 51+)    7

 

Eat at least one dark green and one orange vegetable each day

Choose vegetables and fruit prepared with little or no added fat, sugar or salt

Have vegetables and fruit more often than juice

   8 to 10

Grain products

Females (age 19-50) 6-7
Males (age 19-50)    8
Females (age 51+)   6
Males (age 51+)     7

Make at least half of your grain products whole grain each day 

Choose grain products that are low in fat, sugar or salt

  7 to 8

Milk and alternatives

Females (age 19-50)    2
Males (age 19-50)        2
Females (age 51+)       3
Adult Males (age 51+)  3

 

Drink skim, 1% or 2% milk each day

Select lower-fat milk alternatives such as soy beverages

  2 to 3

Meat and alternatives

Females (age 19-50)  2
Males (age 19-50)      3
Females (age 51+)     2
Males (age 51+)        3

 

Have meat alternatives such as beans, lentils and tofu often.

Eat at least two Food Guide servings of fish each week. (Health Canada provides advice for limiting exposure to mercury from certain types of fish)

Select lean meat and alternatives prepared with little or no
added fat or salt

   2 to 3

What about medication?
High blood pressure affects approximately a quarter of Canadian adults. Many people require medication to control their blood pressure. Lifestyle modification, which includes healthy eating and regular physical activity, may be the only treatment needed in those with mild high blood pressure. In those that require medication to control their blood pressure, following a healthy lifestyle may reduce the need for, or the amount of, medication required.

What next?
A full healthy lifestyle, including healthy eating, is part of the Canadian recommendations for the management of high blood pressure. The Heart and Stroke Foundation is involved in developing blood pressure guidelines, which are updated every year. To control your blood pressure and reduce the risk of heart disease, the guidelines recommend that you:

  • Be active 30 to 60 minutes most days of the week.
  • Choose the following more often: vegetables, fruit, low-fat dairy products, foods low in saturated and trans fat and salt, whole grains and fish, poultry and lean meat. Limit fast foods, canned or prepared foods, as they usually contain high levels of sodium.
  • If you are overweight, losing about 10 lb (5 kg) will lower your blood pressure. Reducing your weight to within a healthy range for your age and gender will lower your blood pressure even more.
  • Eat less salt by:
    • limiting your use of salt in cooking and at the table
    • avoiding salty foods
    • choosing fresh or frozen food
    • avoiding canned or prepared foods that are high in salt
    • reading labels on food packages for sodium content
    • using other seasonings such as herbs, spices, lemon juice and garlic during food preparation
  • If you drink alcohol, limit the amount to 2 drinks a day or less, with a weekly limit of 14 drinks for men and 9 drinks for women. Guidelines do not apply if you have liver disease, mental illness, are taking certain medication, or have a personal or family history of alcohol abuse, are pregnant, trying to get pregnant or breastfeeding. If you are concerned about how drinking may affect your health, check with your doctor.
  • Be smoke-free. It is important to stop smoking if you have high blood pressure. Smoking increases the risk of developing heart problems and other diseases. Your home and workplace should also be smoke-free.
  • Take your medication as prescribed.
  • Monitor your blood pressure regularly.

Changing your diet means a life-long commitment to healthier lifestyle choices. People who make small changes in their diet over a longer period of time, rather than a dramatic change all at once, are more likely to stay committed to a healthier diet.

If you are considering starting on the DASH diet, discuss it with your healthcare provider first.

How much salt?
The Heart and Stroke Foundation recommends Canadians consume no more than 2,300 mg of sodium (about 1 teaspoon/5 mL of table salt) a day in food preparation and at the table. The amount of salt you eat isn’t just what you shake onto your food – it is already added in large quantities to prepared foods, canned products, snack foods and restaurant meals.

To more information about Canada's Food Guide, go to Health Canada's website or call Health Canada at 1-800-O-Canada (1 800 622-6232) or TTY: 1 800 926-9105.

 

Easy ways to get started on the DASH diet

Change gradually

  • If you now eat one or two vegetables a day, add another serving at lunch and dinner.
  • If you don’t eat fruit now or have only juice at breakfast, add a serving to your meals or have it as a snack.

Treat meat as one part of the whole meal, instead of the main focus.

  • Limit meat and alternatives to about 6 oz (170 g) a day, over two meals (two servings). Each serving is about the size of a deck of cards or the palm of your hand.

Choose fruit or low-fat foods as desserts and snacks.

  • Fruit and low-fat foods offer great taste and variety. Fresh fruit require little or no preparation. Dried fruit is easy to carry with you.

If you would like to create a personalized action plan for healthier living, take the Heart&Stroke Risk Assessment.

Last reviewed February 2008.