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Hypertension is the medical term for high blood pressure. Each time the heartbeats, it forces blood into the arteries. Blood pressure is the force created when blood moving through the body’s arteries pushes against the artery walls. Arteries are the blood vessels that carry blood from the heart throughout the body. Though many factors can cause hypertension, diet plays a major role in controlling high blood pressure.
(Illustration by GGS Information Services/Thomson Gale.).
Blood pressure is measured as it pushes against the inside of artery walls. The low blood pressure point, when the heart is at rest, is called diastolic pressure. Blood pressure is measured in millimeters of mercury (mm Hg) and the systolic reading is read and recorded first, with the diastolic pressure reading following. For example, if a person’s high, or systolic, pressure is 118 and his or her low pressure is 70, the blood pressure would be announced and recorded as 118/70 mm Hg, or “118 over 70.” This would fall into the normal range, according to the American Heart Association (AHA). The association’s recommended blood pressure levels are less than 120 mm Hg for systolic pressure and less than 80 mm Hg for diastolic pressure.
If a person’s systolic pressure rises above 120 mm Hg and up to 139 mm Hg or diastolic pressure rises to a level of 80-80 mm Hg, the person is considered “prehypertensive.” High blood pressure is defined as a reading above 140 mm Hg systolic or 90 mm Hg diastolic. If the systolic raises above 160 mm Hg or the diastolic goes above 100, the person is considered in the Stage 2 high blood pressure range. High blood pressure can have serious health consequences. In particular, it is a major risk factor for stroke and heart attack.
Diet is an important part of controlling high blood pressure. A diet to control hypertension consists of eating fewer calories, reducing salt, eating more potassium, reducing alcohol consumption and eating lots of fruits and vegetables. Eating fewer calories and reducing fat, especially saturated fat, will help keep weight down. And lowering weight to normal range usually helps lower blood pressure. Salt is well known as a problem for people with high blood pressure. Most diets for hypertension includes decreasing use of table salt and sodium in processed foods.
Potassium can do the opposite of sodium; it can help lower blood pressure. Potassium is best found in foods rather than in supplements. Foods rich in potassium include apricots, avocados, bananas, melons, kiwis, lima beans, oranges, prunes, spinach, tomatoes, squash, potatoes, and whole grains. Fresh fruits and vegetables are low in sodium, rich in potassium and fiber, as well as vitamins and minerals.
Plant proteins also may help lower blood pressure; the best sources of proteins come from soy products, beans, peas, lentils, peanuts, brown rice, broccoli, and potatoes. A hypertension diet may be supplied by a physician, a center that specializes in heart healthy lifestyles, a nutritionist, or be based on the “DASH” or Dietary Approaches to Stop Hypertension eating plan.
The DASH diet emphasizes lean meats, fish, chicken, low-fat dairy, fruits, vegetables, whole grains, legumes, nuts, and seeds. Vegetarian diets also may help keep blood pressure low. The OmniHeart diet is similar to DASH but may emphasize a particular food group, such as protein, more. Other lifestyle changes, such as quitting cigarette smoking and increasing activity by regularly exercising also may be recommended.
Nearly one in three adults, or about 65 million people, in the United States have high blood pressure. Of these, about one-third do not know they have the disease because there are no real symptoms. The American Heart Association reports that in 2002, high blood pressure killed more than 49,000 Americans and was listed as a primary or contributing cause of death in more than 261,000 deaths in the United States. Blacks get high blood pressure more often than whites. Men are more likely to develop the disease between age 35 and 55, while women are more at risk for hypertension after menopause. In 2003, a report found that high blood pressure incidence was even rising among children and was most likely due to the increased number of overweight and obese children and adolescents.
For years, physicians have known that controlling the amount of salt one eats could help control hypertension. But this can be difficult, since much of the sodium people eat today comes from prepared and pre-packaged foods. Other dietary factors also contribute to high blood pressure. In the 1990s, scientists from the National Heart, Lung, and Blood Institute (NHLBI) conducted key studies to look at the effects of diet on blood pressure. These trials, called “DASH”, showed that an eating plan low in saturated fat, cholesterol and total fat, but high in fruits, vegetables and low-fat dairy foods helped lower blood pressure. DASH trials also followed the effects of a reduced sodium diet on blood pressure. As a result, a comprehensive eating plan was developed with specific suggestions from each food group.
The American Heart Association revised its dietary guidelines in 2000 to build upon the Step 1 Diet, also created by the NHLBI to reduce risk of cardiovascular disease. Later research found that eating fiber could lower blood pressure. In 2006, scientists also recommended that as long as people were on a healthy diet, replacing some of the carbohydrates recommended in diets such as DASH, with proteins and monounsaturated fats can further lower blood pressure.
High blood pressure cannot be cured and is a condition that lasts a lifetime. People with hypertension must work throughout their lives to control their blood pressure and keep it within normal ranges. Many will do so with careful monitoring of blood pressure and a combination of lifestyle and diet changes, as well as possible use of medications.
Since manufacturers add sodium to preserve canned fish and poultry, choosing fresh fish and poultry instead can make a big difference in the level of sodium in the diet. Alternatives to canned and instant products include Fresh vegetables and pastas and rice.
Not everyone is sensitive to salt; some people have high blood pressure for other reasons such as heredity. But it is estimated that about one-half of people with high blood pressure are “salt-sensitive”. When they eat excessive amounts of salt, their blood pressure rises. Overweight and obesity are other factors affecting blood pressure control; therefore, developing dietary and lifestyle habits aimed at maintaining or losing weight are encouraged. Closely following a diet such as DASH or one prescribed by a physician to keep weight in the normal range will help control blood pressure. In addition to controlling blood pressure, people who follow eating plans that consist of controlled portions, balanced intake from all food groups, and reduced sodium will enjoy other heart-healthy benefits, such as lower cholesterol.
Eating plans such as DASH or those suggested by a physician must be followed carefully in order to work. Learning how to read labels and to recognize hidden salt in prepared dishes is as important as pushing away the saltshaker at meals. People who begin the DASH eating plan may want to gradually work up to the increased amount of fiber to prevent bloating and potential diarrhea. People with kidney trouble or heart failure should talk with their physicians before starting a diet that boosts potassium.
A diet for hypertension helps prevent high blood pressure or is one tool to control blood pressure. Diet is not a substitute for prescribed medications, so patients should never stop taking medicines prescribed for high blood pressure without checking with their physicians.
It is important to involve a physician or registered dietitian in diet planning for high blood pressure and to check the advice of credible organizations such as the American Heart Association, the American Dietetic Association, or the National Heart, Lung, and Blood Institute for information on diets recommended by those other than physicians and health care providers.
People with high blood pressure should not rely on “fad” diets for quick weight or blood pressure fixes.
In a clinical trial the DASH diet lowered systolic blood pressure for patients with high blood pressure by an average of 11 mm Hg and diastolic blood pressure by an average of 5.5 mm Hg. A review of research also shows that patients with high blood pressure who lost 3% to 9% of their body weight experienced a drop of 3 mm Hg in both systolic and diastolic blood pressure measurements.
Research shows that decreased use of sodium helps lower blood pressure. A review of 17 clinical trials showed that people with hypertension who ate a reduced-sodium diet had reductions of 5 mm Hg in systolic blood pressure and 3 mm Hg in diastolic blood pressure. Research also has shown a link between increased sodium intake and obesity in the United States. Reducing alcohol consumption by nearly two-thirds resulted in improvements of between 2.5mm Hg and 4 mm Hg in blood pressure. Research has shown that vegetarians in industrialized countries generally have lower blood pressures, but in clinical trials, the vegetarian diets reduced systolic blood pressure but had no real effect on diastolic blood pressure.
Heller, Marla. The DASH Diet. Amidon Press, 2005.
American Heart Association. 7272 Greenville Ave., Dallas,.
TX 75231. (800) 242-8721. http://www.americanheart.org>
National Heart, Lung, and Blood Institute. P.O. Box 30105, Bethesda, MD 20284. (301) 592-8573. <http://www.nhlbi.nih.gov>
Teresa G. Odle