The simple facts about blood pressure

High blood pressure is one of the leading killers in North America. But what is it? Here are some facts to give you a better idea how it can slowly creep up on you if not kept in check.

It's 5 p.m. on a Friday in the height of summer. You're heading — along with what seems like 300,000 others — from your home in the city to a secluded weekend escape. Two miles out from the city, traffic slows to a crawl. There's no accident, no construction — simply too many cars trying to move on a highway that just can't accommodate that much traffic. So the pressure builds as you sit in your steaming car, waiting and waiting and waiting.Much the same thing happens when you have high blood pressure. With every beat of your heart, oxygen-rich blood is pumped throughout the nearly 100,000 kilometres (60,000 miles) of blood vessels in your body.

Blood pressure describes the force of that blood as it wends its way through your arteries. As long as the walls of your arteries are clean, smooth and flexible, the blood flows smoothly and your pressure remains low.Sometimes, though, artery walls become stiff, so they're unable to contract and expand easily. Or they get clogged with sticky plaque, clots and other gunk, narrowing the space through which blood can flow. Or too much fluid enters them. When any one of these happens, pressure builds inside your blood vessels and, the next thing you know, you're listening to some white-coated professional reading you the riot act about your diet, exercise, weight and health.

Like the unexpected traffic jam, there are no warning signs of high blood pressure. If you don't have regular checkups with your doctor that include blood pressure monitoring, you could walk around for years with dangerously high levels without a clue. No wonder they call hypertension the silent killer.

Make no mistake: blood pressure can kill. Just as the growing rush-hour tension on the expressway increases the likelihood of an accident, so the growing pressure of blood against arterial muscles increases the risk of serious damage. It could be a clot breaking loose from an artery wall that travels to your brain, causing a stroke. It could be microscopic damage to the artery walls themselves that eventually leads to plaque buildup and a heart attack. Or it could be long-term damage to the heart itself as it's forced to pump harder and harder to get blood through narrowed arteries.Overall, a diagnosis of hypertension means that your risk of heart attack, heart failure, stroke and kidney disease has just skyrocketed. Consider this: if you're between 40 and 70 years old, each 20-point increase in systolic blood pressure (the top number) or 10-point rise in diastolic pressure (the bottom number) doubles your risk of cardiovascular disease.If you lower those readings to normal levels, you reduce your risk of stroke by 35 to 40 percent, cut your risk of heart attack by 20 to 25 percent and lower your risk of heart failure by more than 50 percent.

The benefits of following a hypertension reducing dietary plan  are enormous and, as these studies have shown, — it doesn't take long to make a difference.