It afflicts one in three adults and it’s just as deadly as too much artery-clogging cholesterol. Yet we hardly ever hear about high blood pressure, which has often been called the silent killer because there are no symptoms, and the first inkling some people have that they’re suffering from this condition is when they suffer a heart attack or stroke. “There’s an epidemic of high blood pressure,” says Martha Daviglus, MD, a spokesperson for the American Heart Association and a professor of medicine at Northwestern’s Feinberg School of Medicine in Chicago.

Blood pressure is the force of your blood pushing against the walls of your arteries. The more blood your heart pumps and the narrower your arteries, the higher your blood pressure. Each time your heart beats, it pumps blood, and that action is called the systolic pressure. When your heart is at rest between beats, your blood pressure falls, and that’s the diastolic pressure. Blood pressure readings use these two numbers.

Although blood pressure can change from minute to minute, it should normally be less than 120/80 for an adult. Blood pressure that stays in the range of 120–139/80–89 is considered prehypertension. Blood pressure that stays at 140/90 or higher is considered high blood pressure, or hypertension.

When blood pressure is too high, it forces the heart to work harder. That can cause the heart to enlarge, which can lead to congestive heart failure — a condition in which the heart can’t pump enough blood to supply the body’s needs, and this, in turn, can damage other organs. High blood pressure also narrows and thickens the blood vessels, which can trigger heart attacks and strokes, and it interferes with the kidneys’ ability to function, allowing excess waste to accumulate in the blood stream and ultimately causing them to fail. “The arteries lose their tone and elasticity,” Dr. Daviglus says.

While people with kidney abnormalities, adrenal gland tumors, and certain congenital heart defects often suffer from high blood pressure, in some cases, there’s no known cause. But there are several risk factors, including age, race (it’s much more common among African Americans), and family history. However, we’re not at the mercy of our genetic destiny, says Dr. Daviglus, “because our lifestyles exert a much more powerful influence.”

In fact, being overweight or obese, smoking, and not getting enough exercise are major contributors. Probably one of the biggest culprits is ingesting too much sodium. Sodium, also known as salt, absorbs water and thereby increases the volume of blood in your system. That, in turn, spikes blood pressure. Yet most Americans consume double the recommended dose of 2,300 milligrams of sodium (about one teaspoon) per day. Those who are more prone to high blood pressure, which includes people over 40 and all African Americans, shouldn’t exceed 1,500 milligrams per day.

Good health habits can control and prevent high blood pressure. Keep weight down, exercise, don’t smoke, keep stress to a minimum, and drink alcohol sparingly. And even a modest reduction in salt intake can trigger a drop in blood pressure among people suffering from hypertension, according to a 2009 British study. If lifestyle changes aren’t enough, your doctor might prescribe a diuretic, beta blocker, or ACE inhibitor to control your blood pressure. But by making sensible lifestyle choices, Dr. Daviglus says, you can prevent high blood pressure altogether.