Of the myriad numbers that define you--height, shoe size, ZIP code, weight, age, Social Security and telephone--the most crucial for your health may be the ones that represent your blood pressure. If your numbers are up, you could be courting serious health problems.
About 50 million Americans--one in five--have high blood pressure, or hypertension, as it's more formally known. It ranks alongside high blood-cholesterol levels and cigarette smoking as a major risk factor for heart disease, the nation's leading killer, and stroke (third on the deadly list behind cancer). About 20% of Americans with high blood pressure don't even know they have the condition, and only one-third have it under control.
Fortunately, not all the news is gloomy. Hypertension can be detected easily and painlessly. With the many drugs now available, most cases can be controlled, usually with minimal side effects. And recent studies show that many people with mild hypertension need not rely on drugs: If they have the will power, they can often lower their blood pressure to normal levels through changes in lifestyle.
Blood pressure is the amount of force exerted on the walls of arteries as blood flows through them. It's measured with an instrument called a sphygmomanometer. The higher, or systolic, pressure represents the maximal pressure on the arteries, which is generated during the heart's contraction; the lower number is the diastolic pressure, the force blood exerts as it continues flowing through the arteries while the heart refills between beats. Blood pressure is written as systolic/diastolic, as in 120/80 mm Hg (millimeters of mercury), the classic "normal" blood pressure.
High blood pressure is defined as systolic pressure higher than 140 mm Hg and/or diastolic pressure greater than 90 mm Hg. That cutoff is based on numerous population studies that have shown that hypertension-related deaths and illnesses rise sharply beginning around the 140/90 level.
High blood pressure ranks as the main cause of stroke because it weakens arteries in the brain, paving the way for a rupture or blood clot. It also contributes to coronary atherosclerosis (the buildup of fatty deposits in the arteries that nourish the heart), which increases the risk of a heart attack. It damages tiny vessels in the kidney that are needed for filtering the blood, which can lead to kidney failure. High blood pressure can also cause blindness, by damaging vessels that provide blood to the eye's retina.
Clearly, hypertension runs in families.
"If you have one parent with hypertension, you have about a 25% chance of developing it," said Dr. William Manger, chairman of the board of the National Hypertension Assn. "If both your parents are hypertensive, your risk of developing it rises considerably, probably to more than 60%." Efforts are under way to find the gene or genes involved.
Controllable factors can also bring about hypertension. These include being overweight and consuming a high-salt diet or a lot of alcohol. Then again, these factors may trigger hypertension only among those who are genetically susceptible.
For many people with hypertension, modifying lifestyle factors can control hypertension without recourse to drugs. In fact, in the most important shift in hypertension treatment in recent years, doctors are now emphasizing lifestyle changes rather than drugs. That has special implications for the 35 million people--70% of hypertensive Americans--who have mild hypertension, defined as a diastolic reading between 90 and 104.
Not long ago, such patients were almost invariably treated with drugs. But in its 1988 report, the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure stressed that non-drug therapy should be the initial treatment for mild hypertension and should be used to supplement drug treatment when patients have higher blood pressure.
Four approaches in particular are well worth trying:
* Weight loss. For hypertensives who are overweight--and about half of them are--losing weight rates as the single most useful lifestyle change they can make. An analysis of five studies involving weight loss and hypertension found that on average, losing 20 pounds resulted in a decline of 6.3 mm Hg in systolic pressure and 3.1 mm Hg in diastolic pressure.
* Reducing sodium intake. Salt accounts for most of the sodium in the diet, and cutting back may help lower blood pressure, although usually not as dramatically as weight loss. Up to half of all hypertensives are "sodium sensitive" and will benefit from reducing their salt intake. And the reductions need not be drastic. One recent study shows that hypertensives aged 50 to 59 who reduce salt intake by just three grams per day can lower systolic pressure by about 7 mm Hg and diastolic pressure by about 3 1/2 mm Hg. (Americans on average consume eight to 10 grams of salt, or two to three teaspoons, per day.)
* Drink less alcohol. Studies show that heavy drinkers (those consuming six or seven drinks a day) are twice as likely as teetotalers to have hypertension. According to one estimate, heavy drinking may be the cause of high blood pressure in as many as 11% of men who have it.
* Exercise. It's difficult to study exercise in isolation, because it often causes other beneficial changes, such as weight loss, that also help against hypertension. Nevertheless, some experts believe regular aerobic exercise itself can lower blood pressure.