Why lower blood pressure?
The World Health Organization estimates that nearly two-thirds of all strokes and half of all cases of heart disease, such as myocardial infarction and heart failure, are caused by high blood pressure. [1]

Factors such as obesity, physical inactivity, and an unhealthy diet are known to contribute to the development of high blood pressure, so avoiding these as much as possible can help reduce the risk of serious heart problems.

Doctors and public health experts have issued guidelines on how best to treat high blood pressure and all of these emphasize the importance of a healthy diet, alongside other lifestyle changes, as a first step towards keeping blood pressure under control. These guidelines also agree that, while some people need medications to lower their blood pressure, in others a healthy diet and lifestyle may be the only treatment necessary.

To find out more about high blood pressure and its treatment, click here.

A normal blood pressure reading

When are dietary changes most effective?
While everyone with high blood pressure will benefit from having a healthy lifestyle there are two groups of people in particular that will benefit from lowering high blood pressure via changes to the diet: 

1. People who are overweight or obese, or have diabetes and who are  therefore at higher risk of heart disease or having higher blood pressure than normal 
   
2. People with borderline or mildly elevated blood pressure, in whom dietary changes may be the only treatment necessary

Even small reductions in blood pressure are associated with a reduced risk of heart disease. Furthermore, dietary changes have no known harmful effects, can improve overall sense of well-being, are inexpensive, and can also enhance the effectiveness of drugs used to lower blood pressure.

Weight matters
Being overweight or obese can cause the blood pressure to rise, putting additional strain on the heart. Sensible weight loss has been shown to reduce blood pressure, however, and has beneficial effects on other risk factors for heart disease, including diabetes and blood cholesterol levels. The blood-pressure-lowering effect of weight reduction may be enhanced by increasing physical exercise levels at the same time, avoiding drinking too much alcohol, and reducing salt intake.

The ideal body weight is often defined as a body mass index in the range 18.5–24.9 kg/m2. To calculate your body mass index click here. 

Weight loss tips Work out a weight-loss program with your doctor or dietician Always aim for steady and gradual weight loss Know your recommended daily calorie intake and stick to it Take up moderate, but regular aerobic exercise, such as walking, jogging, or swimming Avoid heavy physical exercise if your blood pressure is very high or poorly controlled

Limit salt intake
Dietary salt intake is linked to increased blood pressure, so reducing salt intake in the diet can help some people to lower their blood pressure. This can also boost the effectiveness of blood-pressure-lowering medications.

Doctors recommend that people with high blood pressure restrict their salt intake to less than 6 grams per day, equivalent to 2.4 grams per day of dietary sodium.

How to reduce salt intake Get in the habit of checking food labels – you might be surprized to find which foods contain sodium (salt) Choose low-, reduced- or no-added-salt versions of food Limit foods that are cured, pickled, smoked, or in brine Cut down on condiments such as soy sauce, mustard, and ketchup, and eat fewer olives Don’t cook with salt if you can avoid it Don’t have a salt shaker on the table Use spices, herbs, lemon, or vinegar as flavorings instead of salt

Eat a potassium-rich diet
People with high blood pressure should try to include foods that are rich in potassium in their diet, such as many fruits and vegetables. This is because this mineral is important for keeping blood pressure under control, and also reduces the risk of developing kidney stones and bone loss. While potassium is important to include in the diet, you should always check with your doctor before taking any additional supplements, and try to alter the diet first.

Potassium-rich foods Many fruits and vegetables (for example, bananas) Some dairy products Lean meats and poultry (for example, chicken and turkey) Nuts, seeds, and legumes Fish (for example, cod, halibut, rockfish, trout, and tuna)

Eat a healthy and balanced diet

Drink alcohol in moderation
There is a direct relationship between the amount of alcohol consumed and blood pressure, with excess (binge) drinking known to increase the risk of having a stroke. Alcohol can also reduce the ability of some drugs used to lower blood pressure, and is of course high in calories, and associated with other health problems, such as liver disease.

People with high blood pressure should try to limit their alcohol intake to no more than two alcoholic units per day for men and no more than one alcoholic unit per day for women. One unit is equivalent half a pint of normal strength beer (500 ml), a small glass of wine (120 ml), or one measure of spirits (25 ml).

Practical tips to help limit alcohol intake Be aware of how much you normally drink Have at least two drink-free days a week Use a spirit measure at home to avoid over-generous servings Try to substitute every other drink with a non-alcoholic beverage Heavy drinkers (five or more drinks per day) should see their doctor before trying to cut down on alcohol

Other diet tips
The dietary recommendations above have been shown to have a directly beneficial effect on blood pressure. However there are many other ways of changing your diet that will help you stay fit and healthy and reduce your overall risk of developing cardiovascular disease.

Other elements of a healthy eating plan Reduce intake of saturated and total fat Increase consumption of omega-3 fatty acids (found in oily fish such as mackerel, trout, herring, sardines, tuna, and salmon) Eat foods rich in alpha-linolenic acid (for example, tofu, soybeans, canola, walnut, and flaxseed)

Reference

1. World Health Organization. The World Health Report 2002: Risks to Health 2002. Geneva: World Health Organization.

Further reading list

High blood pressure. Patient UK. Accessed 20 December, 2006.

Hypertension. Patient Health International. Accessed 20 December, 2006. 

Lifestyle and risk reduction. American Heart Association. Accessed 20 December, 2006.

Patient Information: Hypertension, diet and weight. UpToDate Patient Information. Accessed 20 December, 2006. Your guide to lowering high blood pressure. National Heart Lung And Blood Institute. Accessed 20 December, 2006.