context: High blood pressure -- in men and women -- is a big problem. One in every three adult Americans -- about 65 million people -- have high blood pressure, also known as hypertension. Many more are at risk of developing it. Over half of all Americans age 60 and older have it and over a lifetime, the risk of developing high blood pressure is 90%. Typically, blood pressure increases with age. Risk of high blood pressure begins to climb when people hit age 45, although it can occur in younger people. African- Americans tend to develop it younger and have more severe hypertension. Obesity or a family history of high blood pressure also increases risk. High blood pressure is especially dangerous, because people can have it for years without knowing. In fact, one in three Americans with the condition doesn't know it. Despite these gloomy statistics, high blood pressure is not inevitable. There is plenty you can do to prevent, delay, and treat the condition. What is high blood pressure? Blood pumping through the circulatory system is under pressure, much like the water in the pipes of a house. And just as too much water pressure can damage pipes and faucets, high blood pressure can spell trouble. Hypertension occurs when the force exerted against artery walls is abnormally high. Over time, the increased pressure can cause a wide range of problems. Small bulges, called aneurysms, may form in blood vessels. The heart can become enlarged, increasing the danger of heart failure. Damage to blood vessels in the kidneys can cause them to fail. Because tiny blood vessels in the eyes are especially vulnerable to damage, hypertension can lead to vision problems and even blindness. Many factors can lead to high blood pressure. Clearly, diet plays a role. Too much salt, too little potassium, and too much alcohol have all been found to increase the risk of high blood pressure. Too much stress and too little physical activity both increase the danger of developing high blood pressure, as does being overweight or obese. And as with many chronic illnesses, high blood pressure also tends to run in families, suggesting that genetics plays a role. In some patients, high blood pressure is related to other medical problems or can be a side effect of certain drugs. This form of the disease is called secondary hypertension, because it happens secondary to other medical conditions. High blood pressure is usually diagnosed using the familiar blood pressure test that involves a cuff wrapped around the upper arm. The cuff is inflated and then sensors measure the pressure of blood beating against the arteries. Blood pressure is measured using two numbers -- systolic and diastolic pressure. Systolic, the upper number, is the pressure when the heart is beating. Diastolic, the lower number, is the pressure between beats. Normal blood pressure is considered to be anything below 120/80. Prehypertension is defined as a systolic reading between 120 and 129 and a diastolic reading lower than 80. Hypertension is defined as blood pressure of 130/80 or higher. medication is recommended for people over age 65 with blood pressure is defined as 130/80 or higher. How can I prevent high blood pressure? To prevent high blood pressure, first consider your diet. A healthy diet can go a long way toward preventing high blood pressure. Trying following the Dietary Approaches to Stop Hypertension eating plan, also known as the DASH diet, which emphasizes plenty of fruits and vegetables and low-fat or nonfat dairy products. Studies conducted by the National Institutes of Health have shown that the DASH diet can lower blood pressure. And the results show up fast -- often within two weeks. At the same time, cut down on salt (sodium chloride), which can raise blood pressure. The National High Blood Pressure Education Program recommends no more than 2,300 milligrams of sodium a day. The ideal is even lower -- only 1,500. For the average person, who consumes about 4,200 milligrams a day, that requires a big change. But studies show that the lower your salt intake, the lower your blood pressure. Along with a healthier diet, it is smart to be as active as possible to prevent high blood pressure. Researchers at the University of Minnesota published results from a study of almost 4,000 people between the ages of 15 and 30 who were followed over time. The more active they were, the lower their risk of developing hypertension. A few other changes can also keep your blood pressure in check. Both excessive alcohol consumption and smoking can raise blood pressure. People who drink alcohol should stick to no more than two standard drinks a day. And if you smoke, the advice is obvious: Get serious about quitting. How is high blood pressure treated? Doctors have a wide range of high blood pressure medicines available to treat high blood pressure. These high blood pressure treatments include diuretics -- often called "water pills" -- beta-blockers, calcium channel blockers, angiotensin converting enzyme ( ACE) inhibitors, angiotensin II receptor blockers ( ARB), and other types of medication. As effective as these drugs can be at controlling blood pressure, if you get to the point of needing them, you may have to take them for the rest of your life. That is one more good reason to focus on prevention.