The Heart and Stroke Foundation has issued updated guidelines based on new medical evidence for preventing and controlling high blood pressure, one of the leading causes of death among Canadians.

Known as the "silent killer," high blood pressure (hypertension) presents no obvious symptoms to warn people they could be in trouble until it's too late.

Updated recommendations from Heart and Stroke Foundation

High-normal: One in five Canadians has high-normal blood pressure (130-139/85-89). Of those who are overweight and have high normal blood pressure, 40 per cent will develop hypertension within two years and 60 per cent will become hypertensive within four years. Adults with borderline high blood pressure should have it checked once a year, minimum.

Ditch the salt shaker: Reduce your intake of salt and other forms of sodium, which are often sprinkled liberally in prepared foods. Too much sodium can cause high blood pressure.

Get it checked: All Canadian adults should have their blood pressure tested during visits to the doctor. Blood pressure increases with age, so that half of Canadians over 65 have hypertension. More than 90 per cent of those 65-plus will eventually develop the condition.

Other risks: More than 90 per cent of Canadians with high blood pressure have other cardiovascular risks, such as diabetes. Identifying and managing these other factors can reduce the overall risk of cardiovascular disease by more than 60 per cent.

Modify lifestyle: Hypertension can be prevented by taking a number of steps, including adopting a healthy diet, getting regular physical activity, drinking alcohol in moderation, avoiding smoking and reducing stress.

Source: Canadian Press

Uncontrolled, it can lead to heart attack, stroke, kidney failure and dementia, and it is far more common than many people believe.

Almost a quarter of Canadian adults, or about five million, have hypertension — defined as having a blood pressure reading that exceeds 140/90. Normal blood pressure is 120/80 or less. The first number is systolic pressure (when the heart contracts) and the second is diastolic (when the heart relaxes).

The new recommendations are aimed in particular at an estimated 2.5 million Canadians whose blood pressure falls in the "high-normal" range — 130 to 139 systolic/85 to 89 diastolic.

"As the blood pressure increases and gets into the high part of the range, we call that high-normal blood pressure," Dr. Sheldon Tobe, a spokesman for the Heart and Stroke Foundation, said Thursday.

"And the new information we have is that … about half of people with high-normal blood pressure will develop full-blown hypertension in four years," said Tobe, a kidney specialist at Sunnybrook Health Sciences Centre in Toronto, citing findings of a recent U.S. study.

Check for "hidden" sodium

That means an estimated one million more Canadian adults will be living with high blood pressure and all the threats it poses to their health — unless it is diagnosed and treated either with lifestyle changes and/or medications, he said.

The new recommendations also strengthen warnings about sodium intake, advising Canadians to cut back on dousing meals with table salt and ingesting other "hidden" forms of sodium, which can elevate pressure by increasing blood volume.

Daily intake should not exceed 2,300 milligrams, said Tobe, noting that many prepared foods are "loaded with salt." Even healthy foods can contain lots of salt, he said, noting that a 347-millilitre of V-8 juice contains 900 milligrams of sodium.

The Heart and Stroke Foundation advises reading labels on prepared foods because many contain high levels of sodium. Ketchup, mustard, pickles, peanut butter and canned, bottled or packaged convenience foods are big salt offenders, as are many snack foods: think potato chips, popcorn and crackers.

The 2007 guidelines also maintain the well-known but not-always-followed mantra to get regular exercise, eat a low-fat diet rich in fruits and vegetables, achieve or maintain a healthy weight, drink alcohol in moderation, don't smoke, reduce stress and have blood pressure checked at least once a year.

Blood pressure checks

Getting the word out about the updated recommendations should make the public more aware of the need for regular blood pressure testing and for taking steps to control it, said Tobe, and it's also critical for updating doctors on the best ways to do that.

"Hypertension is the No. 1 reason for visits to primary care, so it's very important for family docs" in managing their patients with high blood pressure, he said.

And those who think hypertension is a disease only of older people should think again.

"One in 10 young men aged 18 to 35 have high blood pressure," Tobe said, quoting figures from the most recent Canadian Heart Health Survey. "Many of these young men go undiagnosed because they're otherwise healthy and they often don't see their family doctors."

"And if they do, it's not to have their blood pressure checked."

These young men are at the highest risk for serious health conditions, he said, because "they go the longest with undiagnosed and untreated high blood pressure."

For females, hypertension tends to be a disease related to aging. After age 65, more women than men have high blood pressure, likely as a result of losing the protective effects of estrogen and other sex hormones after menopause.

If people with high-normal blood pressure are identified and change their lifestyle, they may not need medication or delay the need for it by years or decades, Tobe said.