A smart guide to understanding high blood pressure

Some 5.5 million Canadians have high blood pressure, but only about 58 percent of them know it. This is unfortunate, because this virtually symptomless — but potentially dangerous — condition is easy to treat with the right lifestyle choices and drugs.

High blood pressure is often a complex result of who you are (genetics), what you eat and how you live. There are three main ways your body raises its blood pressure.

1. Your heart can change the rate and strength of its beats.
2. Your small arteries (arterioles) can constrict for various reasons, making higher pressure necessary to circulate your blood.
3. Your kidneys can keep more water in your body, creating more blood volume to pound through your vessels. The kidneys do this by releasing hormones that increase your body’s supply of sodium (and a salty diet provides a ready source).

When someone’s blood pressure is routinely high, doctors diagnose it as hypertension. If you're like most people with high blood pressure, you probably have primary hypertension. Even though its cause is unknown, it accounts for about 90 percent of cases.

• In only a few people (about 10 percent) can high blood pressure be linked to something specific, such as kidney disease or long-term use of certain drugs (NSAIDs, corticosteroids, oral contraceptives). This is known as secondary hypertension, and eliminating the underlying problem is often the only treatment you'll need.

Most people know that their "normal" blood pressure is supposed to be 120/80. The systolic number on the top (120) indicates the highest pressure exerted on your artery walls as the heart contracts to pump the blood out; the diastolic on the bottom (80) reflects the moment of lowest pressure, when it relaxes between contractions.

• It’s natural for blood pressure to fluctuate throughout the day, reflecting what you're doing. It drops during sleep, for instance, and spikes during exercise or in times of stress or pain.

Over time, high blood pressure can inflict lasting damage.

• Your overworked heart muscle may get so big that it becomes flabby and inefficient, causing heart failure.
• Vessels that supply blood to your eyes, brain and various organs may become so stretched or strained that they leak or burst, causing stroke or internal bleeding.

• Lifestyle changes (low-sodium diet, stress reduction, weight loss, regular exercise) to naturally lower your blood pressure.
• If lifestyle measures fail, medications — or combinations of different drugs — to medically lower your blood pressure.
• For more complicated cases, eliminating the cause — whether it’s a drug, illness or other underlying problem.

• Choose nutrients with blood vessels in mind. Omega-3 fatty acids found naturally in oily fish such as salmon will benefit hypertension by keeping your blood vessels flexible. Eat fish three times a week.
• Stay alert for symptoms. Although hypertension has a reputation as a mysterious "silent" condition, some people develop recognizable symptoms. If headaches and vision problems occur, contact your doctor.
• Watch for seasonal changes. The weather affects blood pressure in some people. If you notice a significant increase during cold winter months, talk to your doctor about altering your treatment to compensate.
• Keep an eye on your top number. For years, doctors focussed on the lower number — the diastolic. Now research indicates the top number — the systolic — is even more strongly linked to heart-related illness and death.   

• The Heart and Stroke Foundation of Canada has detailed information about hypertension, blood pressure monitoring devices and drugs; it also compares the DASH diet to Canada’s Food Guide to Healthy Eating (613-569-4361 or www.heartandstroke.ca).

The most effective way to lower your blood pressure is to make healthy lifestyle changes. For more information, be sure to contact your doctor.