Hypertension, or high blood pressure, is a serious condition that affects 50 million Americans—one in four adults. It is defined as an average systolic blood pressure above 140 mm Hg, a diastolic blood pressure above 90 mm Hg, or both. High blood pressure increases the risk of heart disease and stroke, the first and third most common causes of death among Americans. In the early and middle adult years, men are more likely than women to develop the condition, but as men and women age, the reverse is true; more women older than the age of 55 have high blood pressure than men of the same age. While hypertension generally develops in people older than 20 years of age, more than half of all Americans over the age of 65 have the condition.
Signs and SymptomsMost people who have high blood pressure do not know they have it because they generally experience no symptoms at all. Occasionally, some individuals may experience a mild headache when their blood pressure is high. Serious cases of hypertension, which happen infrequently, may produce the following symptoms:
- Severe headache
- Visual disturbances
CausesThere are two major types of hypertension: essential (primary) and secondary. Essential hypertension is by far the most common, accounting for more than 95% of all cases. The cause of this form of hypertension is not known for certain, but is likely a combination of factors, including:
- Genes for high blood pressure
- Low levels of nitric oxide, a naturally occurring agent responsible for the dilation of blood vessels (African Americans are believed to have low levels of this substance)
- Insulin resistance
- Kidney disorders
- Endocrine disorders, such as Cushing's syndrome
- Obstructive sleep apnea (episodes during sleep when breathing stops due to obstruction of the air passages)
- Chronic heavy alcohol consumption (accounts for 10% of cases of secondary high blood pressure)
- Long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs), particularly in the elderly
- Use of certain medications, including oral contraceptives, pseudoephedrine, hormone replacement therapy, and steroids
- Heavy coffee drinking (5 or more cups per day), particularly in those who have previously had high blood pressure
- Use of cocaine, nicotine, or licorice (Glycyrrhiza glabra) can cause or worsen existing hypertension
Risk FactorsThe following factors increase an individual's risk for high blood pressure:
- Family history of hypertension
- Alcohol abuse
- High sodium intake
- Inactive lifestyle
- Being overweight
- Mood disorders, particularly depression and anxiety (they may have a direct impact on blood vessels or they may lead to unhealthy behaviors such as alcohol and substance abuse or poor weight management)
- Hypertension is more common among African Americans than Whites (this may be due to nitric oxide levels or to social factors such as chronic life stressors)
DiagnosisBlood pressure is the force of the blood pushing against the walls of the arteries. Each time the heart beats, or contracts, it pumps blood into the arteries. Blood pressure is at its maximum at this time; this is known as the systolic blood pressure. When the heart is at rest, between beats, the blood pressure falls; this is known as the diastolic pressure. A person with hypertension has an average systolic blood pressure above 140 mm Hg and/or a diastolic blood pressure above 90 mm Hg (usually written as 140/90).
To diagnose hypertension, a physician will obtain a blood pressure measurement during a routine physical examination. An inflatable cuff is wrapped around the arm, and the person taking the blood pressure listens with a stethoscope over the artery. If blood pressure is elevated, the physician will check the pulse rate, examine the neck for swollen veins or an enlarged thyroid gland, listen to the heart for murmurs, feel the abdomen, and examine the eyes for damaged blood vessels in the retina. If the physician suspects hypertension, additional laboratory and blood tests will help determine if it is secondary hyptertension or essential hypertension.
Preventive CareStudies suggest that the following lifestyle factors can help prevent hypertension:
Maintaining a desirable weight
According to several large-scale, population-based studies, being overweight is one of the strongest predictors of development of high blood pressure, including in adolescents and young adults. Similarly, maintaining a normal body weight is one of the most effective ways to prevent high blood pressure. Weight reduction, therefore, in overweight individuals of any age should be a priority in the prevention of hypertension.
Reducing salt intake
Although population-based studies suggest a link between salt intake and prevalence of high blood pressure in particular groups of people (African Americans, for example), how each individual responds to sodium in his or her diet is quite variable. Since reducing dietary salt is generally considered safe, however, low-salt diets are recommended, particularly for those at risk for developing hypertension or heart disease.
Increasing physical activity
Several studies suggest that physically inactive people may be at an increased risk for developing hypertension. According to some population-based studies, men who lead physically active lives can reduce their risk of developing hypertension by 35% to 70%. Although the duration and frequency of exercise necessary to prevent or treat hypertension is not well established, some evidence suggests that low to moderate intensity exercise may be more effective than higher intensity exercise training.
Limiting alcohol consumption
Studies suggest that people who consume three or more alcoholic beverages per day increase their risk for developing hypertension. If an individual is going to drink alcohol, therefore, intake should be limited to no more than two drinks per day.
Eating a diet rich in fruits and vegetables
People who consume vegetarian diets have significantly lower blood pressure than those who do not. The specific nutrients responsible for lowered blood pressure remain largely unknown, however.
Treatment ApproachThe goal in treating hypertension is to reduce the risk of serious complications, including heart disease and stroke. While the optimum blood pressure is 120/80 mm Hg, even partial reduction in blood pressure is beneficial. Prescription medications are often needed to treat hypertension, but lifestyle modifications, including diet, exercise, and relaxation, are necessary with or without medications. In fact, a National Institute of Health (NIH) statement issued in 1996 asserts that behavioral and relaxation therapies must be integrated into conventional medical treatment of high blood pressure. Examples of relaxation techniques include biofeedback, massage, meditation, and qi gong. Often, in the early stages of hypertension when blood pressure elevation is mild, the doctor will recommend lifestyle modifications alone for a period of 6 to 12 months. After this time, if blood pressure is still high, medication will likely be prescribed.
LifestyleThe same lifestyle modifications that help prevent hypertension are useful in treating it. The following steps are recommended for people with hypertension, regardless of whether they are taking prescription medications.
- Lose weight if overweight.
- Limit alcohol intake to no more than 1 oz of ethanol per day for men (this roughly equals 2 pints of beer, 2 glasses of wine, or 2 shots of 100-proof whiskey) and 0.5 oz for women and lighter-weight individuals.
- Increase and maintain aerobic physical activity (30 to 40 minutes most days per week).
- Reduce salt intake to less than 2,400 mg sodium or 6,000 mg sodium chloride per day.
- Maintain adequate intake of calcium (1,000 to 1,500 mg per day for adults) and potassium (approximately 2,000 mg per day for adults) for optimum health.
- Improve overall cardiovascular health by quitting smoking and reducing saturated fat and cholesterol intake.
- Reduce stress—since ongoing stressful circumstances, such as job dissatisfaction, may contribute to the development of hypertension, stress management may lower elevated blood pressure.
MedicationsMedication is recommended for people with sustained systolic pressure above 160 mm Hg or diastolic pressure above 100 mm Hg. There are several medications available to treat hypertension, and the medications prescribed depend on each individual case. 10% of patients may require as many as three drugs to control their condition.
Some of the most commonly prescribed medications include the following.
Diuretics help the kidneys eliminate sodium and water from the body. This decreases the volume of blood in the body and lowers blood pressure.
There are three types of diuretics: thiazide, loop, and potassium-sparing. The effects of these and other types of medications used to treat hypertension follow.
- Thiazide diuretics (such as hydrochlorothiazide)—tend to deplete potassium and may increase cholesterol and blood sugar; should not be used by people with gout or diabetes
- Loop diuretics (such as furosemide and bumetanide)—also tend to lower potassium levels
- Potassium-sparing diuretics (such as spironolactone)—this class does not lower potassium, but side effects may include excessive breast development in men
- Beta-blockers (such as acebutolol, atenolol, metoprolol, nadolol, and propranolol)—slow the heart rate down (thereby reducing the workload on the heart) and diminish stress hormones in the body (which allows blood vessels to relax); side effects may include depression, insomnia, fatigue, and sexual dysfunction; these medications should not be used in the case of heart failure and airway diseases such as emphysema; they should also be avoided by people with diabetes
- Angiotensin-converting enzyme (ACE) inhibitors (such as benazepril, captopril, enalapril, lisinopril, and ramipril)—by inhibiting a chemical reaction in the body, these drugs decrease production of a substance in the body that, in susceptible individuals, increases blood pressure; side effects may include cough, rash, and loss of taste
- Calcium-channel blockers (such as amlodipine, felodipine, nifedipine, nicardipine, and verapamil)—relax blood vessels, thereby lowering blood pressure; side effects may include constipation, nausea, and headache
- Angiotensin II receptor blockers (such as losartan, valsartan, candesartan, irbesartan, and telmisartan)—block the effects of a particular chemical in the body, thereby preventing it from increasing blood pressure; side effects may include dizziness, nausea, diarrhea, back pain, cough, fatigue, fever, shortness of breath, depression, and anxiety
Nutrition and Dietary SupplementsA landmark study known as the Dietary Approaches to Stop Hypertension (DASH) trial determined that eating a balanced, healthful diet that is rich in fruits, vegetables, and low-fat dairy products is very important for prevention and reduction of high blood pressure. For some, when this diet is combined with low salt intake (less than 2,400 mg per day) the improvement in blood pressure may be as effective as taking a medication. One of the main messages from the DASH trial and other important studies is that dietary changes are essential for achieving and maintaining normal blood pressure and that nutrients from the diet work in a complex manner and are of more value than individual supplements.
Specific nutrients and supplements that have been studied for hypertension include the following.
Eating several servings of fruits and vegetables each day can ensure optimal intake of antioxidants such as vitamin C, vitamin E, and beta-carotene, which may protect against the development of hypertension. However, studies have yet to show whether taking supplements of these nutrients is useful for hypertension.
The DASH study mentioned above also compared a diet rich in fruits and vegetables to a diet rich in fruits and vegetables as well as low-fat dairy products. The addition of low-fat dairy products led to a greater improvement in reducing blood pressure than the typical American diet or a diet rich in fruits and vegetables alone. Some experts believe that the calcium in these low-fat dairy products is responsible for the improvement; however, given that dairy products also contain other nutrients such as modest amounts of potassium and magnesium, that conclusion is not entirely clear. In addition, studies that have investigated calcium as a supplemental treatment for high blood pressure have not been conclusive; in other words, it remains to be seen whether taking supplements of calcium will have the same effect on blood pressure as low-fat dairy products in the diet.
Studies including a small number of people suggest that coenzyme Q10 (a substance found in oily fish, organ meats such as liver, and whole grains) may significantly lower blood pressure, but further research is necessary to confirm its potential use for hypertension.
Dietary magnesium may be associated with lowered blood pressure, but most studies have failed to establish a link between magnesium supplementation and lowered blood pressure. Foods rich in magnesium include legumes, nuts, whole grains, and leafy green vegetables.
Omega-3 Fatty Acids
Recent studies indicate that supplementation with omega-3 polyunsaturated fatty acid (PUFA), a substance found primarily in fatty cold-water fish, such as salmon, mackerel, sardines, and herring, may significantly lower blood pressure in people with hypertension. Available omega-3 supplements include eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), flaxseed, flaxseed oil, and fish oil capsules. Fish high in mercury (such as tuna) should be avoided because this may increase blood pressure.
Some studies have linked low dietary potassium intake with hypertension, but results of clinical trials do not suggest that supplementation with potassium lowers blood pressure. A diet high in potassium from fruits and vegetables, such as potatoes, avocados, bananas, oranges, prunes, and cantaloupe, is generally recommended.
Animal studies suggest that vanadyl sulfate (a form of vanadium) may help improve blood pressure. This has yet to be tested on people. Therefore, until more information is available, use of vanadium for this purpose is not currently recommended.
HerbsGarlic (Allium sativum)
Studies suggest that raw garlic may have beneficial cardiovascular effects, including lowered blood pressure, but further research is necessary before it can be routinely recommended for people with hypertension. Since garlic is relatively safe and has a number of other healthful benefits, a professional herbalist may recommend 5 to 10 minced raw garlic cloves per day or 300 mg of dried garlic extract three times per day for those at risk for heart disease.
Hawthorn (Crataegus monogyna)
Although hawthorn has not been studied specifically for hypertension, considerable evidence supports the cardiovascular benefits of this herb. Studies suggest that hawthorn can be taken safely by people with hypertension who are taking blood pressure medications. A professional herbalist may recommend between 160 and 900 mg of hawthorn leaf and flower extract per day for six weeks or more.
Other preliminary studies have revealed beneficial effects for the following herbs:
- Ginkgo (Ginkgo biloba)
- Red Korean ginseng (Panax ginseng)
Several studies involving small numbers of people with hypertension showed a reduction in blood pressure with the use of acupuncture. While these clinical trials were conducted over a short period of time, the encouraging results suggest that it would be worthwhile for scientists to conduct longer term research of acupuncture for treating high blood pressure.
Preliminary evidence suggests that people with high blood pressure who receive chiropractic spinal manipulation experience a significant reduction in blood pressure, but more research is needed to confirm its use for hypertension. In fact, on rare occasions, a spinal manipulation session may actually cause extremely low blood pressure leading to dizziness or lightheadedness.
Massage and Physical Therapy
Massage may be particularly helpful for people with hypertension brought on by stress. This is because the beneficial effects of massage are due at least in part to a reduction in stress. One recent study revealed that people with hypertension who receive massage showed significant reductions in blood pressure and steroid hormones, an indicator of stress. Although more studies are needed to evaluate the long-term safety and effectiveness of massage, people with hypertension who tend to have high levels of stress in their lives may benefit from massage therapy. In addition, massage tends to help people stick with healthy behaviors such as eating healthfully and not smoking.
Although the association between ongoing life stress and hypertension is complex and somewhat controversial, many believe that relaxation techniques may be helpful in alleviating feelings of stress, which is often a contributing factor to hypertension. While the results of studies investigating this relationship have been mixed, one study of older African Americans living in an urban setting found that those who participated in a transcendental meditation (TM) or progressive muscle relaxation (PMR) program had a significant reduction in blood pressure compared to those who participated in a lifestyle education program. While both techniques were beneficial, TM was twice as effective as PMR.
In addition to TM and PMR, other mind/body techniques such as self-hypnosis and biofeedback have shown promising results in recent studies. Biofeedback in particular may reduce elevated blood pressure from stress and help individuals achieve healthful lifestyle modifications, such as stopping smoking and losing weight.
AyurvedaSnakeroot (Rauwolfia serpentina)
This ancient Hindu Ayurvedic remedy is the natural source of reserpine, one of the first commercially available blood pressure medications. Because of its many adverse effects, however, reserpine has been all but replaced by newer, better-tolerated medications. Snakeroot should be avoided by people with depression, stomach ulcers, or ulcerative colitis. Side effects are similar to prescription reserpine and include drowsiness and an inability to concentrate.
This combination herbal remedy has been shown to significantly reduce diastolic blood pressure in people with hypertension.
Abana contains the following herbs:
- Arjun (Terminalia arjun)
- Ashwagandha or winter cherry (Withania somnifera)
- Guguchi (Tinospora cordifolia)
- Indian gooseberry (Emblica officinalis)
- Hundred husbands (Asparagus racemosus)
- Gotu kola (Centella asiatica)
- Muskroot (Nardostachys jatamansi)
- Saffron (Crocus sativus)
- Myrobalan (Terminala chebula)
- Licorice (Glycyrrhiza glabra)—note that when used alone, this herb may cause high blood pressure
The traditional Chinese practice of qi gong, which combines meditation, pulsing or animal-like movements, breathing exercises, spiritual practices, and self-massage, may be a useful addition to lifestyle modifications and medication in treating hypertension, particularly in the elderly. A 20-year study of people taking medications to treat hypertension revealed that the blood pressure in those who practiced qi gong for 30 minutes two times per day remained stable while the blood pressure progressively worsened in those who did not practice qi gong regularly.
The following herbs have also been used in Traditional Chinese Medicine to lower blood pressure. Results of animal and laboratory studies have thus far supported the traditional use for this purpose.
- King of bitters (Andrographis paniculata)
- Linustrum (Lingusticum wallichii)
Blood pressure is monitored frequently during pregnancy because some women may develop high blood pressure for the first time while pregnant. If this occurs, medication may be needed. In addition, a condition known as preeclampsia is very serious and even life-threatening. Preeclampsia is high blood pressure during pregnancy that occurs along with other symptoms and signs, such as swelling of the ankles and legs, blurred vision, liver test abnormalities, and protein in the urine.
Warnings and Precautions
- Avoid fish high in mercury, which may increase blood pressure.
- The use of cocaine, nicotine, or licorice (Glycyrrhiza glabra) can cause or worsen existing hypertension.
- Caffeine can exacerbate high blood pressure.
Prognosis and ComplicationsIf left untreated, hypertension can cause several serious complications, including:
- Coronary artery disease and heart attack
- Congestive heart failure
- Kidney disorder
- Disorders of the retina, which can ultimately lead to blindness
- Impotence in men and decreased orgasm in women
- Memory impairment and dementia
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