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Nearly one in five adult Canadians has high blood pressure, a new survey from Statistics Canada reports. That's about 4.6 million people.

About 61 per cent of Canadians between the ages of 20 and 79 have normal blood pressure, the survey found. But another 20 per cent have readings in the pre-hypertension range, meaning they are at high risk of developing high blood pressure soon.

Men and women are about equal in their rates of high blood pressure: 19.7 per cent of men have the condition, as do 19 per cent of women. But men appear less likely than women to be aware of their condition and many only became aware after they had their blood pressure measured as part of the StatsCan study.

The findings come from the first cycle of the Canadian Health Measure Survey -- the most comprehensive health survey ever carried out in Canada.

Statistics Canada analyst Kathryn Wilkins, who led the survey, says the good news is that hypertension rates don't seem to be rising. In fact, 20 years ago, the rate was slightly higher, at 21 per cent. (The authors note, though, that the surveys used different blood pressure measurement methods.)

"It is encouraging news," she told Â鶹´«Ã½. But she added that it is worrying that there are still so many Canadians who are not aware they have high blood pressure.

The results are based on direct, automated measures of blood pressure taken between March 2007 through February 2009, as well as self-reported use of blood pressure medication. Blood pressure was measured on just 3,514 respondents, aged 20 to 79, but the data were weighted to be representative of the 23.7 million Canadian adults in this age range.

The survey found that about 80 per cent of those adults with high blood pressure are being treated with drugs.

In most of those with the condition (66 per cent), medication has been effective in controlling their blood pressure. But in the remaining third (who account for 6.6 per cent of the adult population), their blood pressure is still too high.

The problem of stubbornly high blood pressure is particularly bad among women. Among women with hypertension  taking medication for their condition, 18 per cent still had blood pressure that was too high. That compares with 10 per cent of men.

This gender gap worsened with age. Among 60- to 69-year-olds who were using blood pressure medication, 19 per cent of women still had blood pressure that was too high, compared with 7 per cent of men.

Still, cardiologist Dr. Christopher Simpson of Queen's University in Kingston says it's heartening to know that so many Canadians are managing their high blood pressure through medication.

"About two-thirds of them have well-controlled hypertension. That stands in stark contrast to the 10 to 15 per cent who had well-controlled hypertension back in 1992. We're doing a much better job getting people well treated," he told CTV.

"The bad news is that one-fifth of Canadians still have high blood pressure."

High blood pressure is defined as systolic pressure (the upper number) of 140 or higher, and diastolic pressure (the lower number) higher than 90. So a reading at or above 140/90 would be considered high. Normal blood pressure is below 120/80 mm Hg.

As well, anyone who reported they had used medication for high blood pressure in the past month was classified as having hypertension.

High blood pressure is the number one risk factor for stroke. And, because high blood pressure can damage blood vessel walls, causes scarring that promotes the build-up of fatty plaque, and strains the heart, the condition is also a major risk factor for heart disease.

The World Health Organization estimates that elevated blood pressure is responsible for about 7.1 million premature deaths each year.

The Heart and Stroke Foundation says that proper treatment of high blood pressure can cut the risk of stroke by up to 40 per cent and heart attack by up to 25 per cent.

High blood pressure typically has no warning signs or symptoms, which is why it is often called a "silent killer."

Blood Pressure Canada, a non-profit group dedicated to the prevention and control of hypertension in Canada, says a number of lifestyle changes can prevent or reduce high blood pressure. They recommend:

• Be physically active for 30 to 60 minutes most days of the week. Even a little bit of physical activity is better than none at all.
• If you are overweight, losing about 10 lbs (5 kg) will lower your blood pressure. Reducing your weight to within a healthy range will lower your blood pressure even more.
• Eat less salt. The usual amounts of sodium in the average Canadian diet are very high and increase blood pressure. One in three Canadians with high blood pressure would have normal blood pressure with a healthy amount of sodium in their diets.
• Buy and eat more fresh foods especially fruit and vegetables.
• Stop smoking. Smoking increases the risk of developing heart problems and many other diseases.
• If you drink alcohol, limit the amount to one to two standard drinks a day or less.