Most people can't tell when their blood pressure is high, which is why hypertension is called the "silent killer." In this case, what you don't know can hurt you. Elevated blood pressure can lead to a greatly increased risk of heart attack, stroke, and many other serious illnesses. Along with high cholesterol and smoking, hypertension is one of the most important causes of atherosclerosis. In turn, atherosclerosis causes heart attacks, strokes, and other diseases of impaired circulation.

The mechanism by which high blood pressure produces atherosclerosis is somewhat similar to what happens in a hose fitted with a high-pressure nozzle. All such nozzles come with a warning label that states, "Make sure to discharge pressure in hose after using." Unfortunately, many people frequently fail to pay attention to the warning and leave the hose puffed up with full pressure overnight. This rather common practice does not produce any immediate consequences. The hose doesn't develop leaks at the seams or burst outright on the first occasion you leave it untended. However, a garden hose that is frequently left under pressure will begin to age more rapidly than it would otherwise. Its lining will begin to crack, its flexibility will diminish, and within a season or two the hose will be sprouting leaks in all directions.

Similarly, when blood vessels are exposed to constantly high pressure, a similar process is set in motion. Blood pressures as elevated as 220/170 (systolic pressure/diastolic pressure), quite common during activities, such as weight lifting, do no harm. Only when excessive pressure is sustained day and night do blood vessel linings begin to be injured and undergo those unhealthy changes known as atherosclerosis.

Although it is important to lower blood pressure with all deliberate speed, only rarely does it need to be lowered instantly. In most situations, you have plenty of time to work on bringing down your blood pressure. However, that doesn't mean that you should ignore it. Over time, high blood pressure can damage nearly every organ in the body.

The best way to determine your blood pressure is to take several readings at different times during the day and on different days of the week. Blood pressure readings will vary quite a bit from moment to moment; what matters most is the average blood pressure. Thus, if many low readings balance out a few high readings, the net result may be satisfactory. However, it is essential not to ignore a high value by saying, "I was just stressed then." Stress is part of life, and if it raises your blood pressure once, it will do so again. To come up with an accurate number, you must include every measurement in your calculations.

In most cases, the cause of hypertension is unknown. The kidneys play an important role in controlling blood pressure, and the level of squeezing tension in the blood vessels makes a large contribution as well.

Lifestyle changes, such as quitting cigarettes, losing weight, and increasing exercise, can dramatically reduce blood pressure. Regarding exercise, one study found that engaging in aerobic exercise 60 to 90 minutes weekly may be sufficient for producing maximum benefits.69Another study found that taking four 10-minute "exercise snacks" of brisk walking per day significantly improves blood pressure.78

For many years doctors advised patients with hypertension to cut down on salt in the diet. Today, however, the value of this stressful dietary change has undergone significant questioning. Considering how rapidly our knowledge is evolving, we suggest consulting your physician to learn the latest recommendations.

If lifestyle changes fail to reduce blood pressure, or if you can't make these alterations, many effective drugs are available. Sometimes you need to experiment with a few to find one that agrees with you.

There are no herbs or supplements for hypertension with solid scientific support. However, the supplement coenzyme Q 10 (CoQ 10) and extracts from the herbStevia rebaudiana have shown some promise in preliminary trials.

Coenzyme Q 10

The supplement CoQ 10 has shown promise as a treatment for high blood pressure, but the evidence that it works is not yet strong.

An 8-week, double-blind, placebo-controlled study of 59 men already taking medication for high blood pressure found that 120 mg daily of CoQ 10reduced blood pressure by about 9% as compared to placebo.7

In addition, a 12-week, double-blind, placebo-controlled study of 83 people with isolated systolic hypertension (a type of high blood pressure in which only the "top" number is high) found that use of CoQ 10at a dose of 60 mg daily improved blood pressure measurements to a similar extent.53

Also, in a 12-week, double-blind, placebo-controlled trial of 74 people with diabetes, use of CoQ 10at a dose of 100 mg twice daily significantly reduced blood pressure as compared to placebo.62

Antihypertensive effects were also seen in earlier smaller trials, but most of them were not double-blindand, therefore, mean little.8-10

For more information, including dosage and safety issues, see the full CoQ10 article.

Stevia

The herb stevia is best known as a sweetener. Its active ingredients are known as steviosides. In a 1-year, double-blind, placebo-controlled study of 106 people with moderate hypertension (approximately 165/103), steviosides at a dose of 250 mg three times daily reduced blood pressure by approximately 10%.12 Full benefits took months to develop. However, this study is notable for finding no benefits at all in the placebo group. This is unusual and tends to cast doubt on the results.

Benefits were also reported in a 2-year, double-blind, placebo-controlled study of 174 people with milder hypertension (average initial BP of approximately 150/95).70 This study used twice the dose of the previous study: 500 mg three times daily. A reduction in blood pressure of approximately 6%-7% was seen in the treatment group as compared to the placebo group, beginning within 1 week and enduring throughout the entire 2 years. At the end of the study, 34% of those in the placebo group showed heart damage from high blood pressure (left ventricular hypertrophy), while only 11.5% of the stevioside group did, a difference that was statistically significant. No significant adverse effects were seen.

However, once again, no benefits at all were seen in the placebo group. This is a red flag for problems in study design. Both of these studies were performed in China, a country that has a documented history of questionable medical study results.71

Furthermore, a study by an independent set of researchers failed to replicate these findings.129And, another study involving people with diabetes, as well as healthy subjects, found that stevia, at a dose of 250 mg three times daily, had no significant effect on blood pressure after 3 months of treatment.130

Furthermore, a study by an independent set of researchers failed to replicate these findings.129And, another study involving people with diabetes, as well as healthy subjects, found that stevia, at a dose of 250 mg three times daily, had no significant effect on blood pressure after 3 months of treatment.130

For more information, including dosage and safety issues, see the full Stevia article.

Relaxation Therapies

Although it seems intuitive that relaxation should lower blood pressure, the evidence for the benefits of relaxation therapiesfor treating hypertension is far from convincing. In a review of 25 studies investigating various relaxation therapies (totaling 1,198 participants), researchers found that those studies employing a control group had no significant effect on lowering blood pressure compared to sham (placebo) therapies.125

More specifically, biofeedbackis widely advocated for treating hypertension. But, in an analysis of 22 studies, real biofeedback when used alone was found to be no more effective than sham (fake) biofeedback.63A subsequent review of 36 trials with 1,660 participants found inconsistent evidence for the effectiveness of biofeedback for treatment of hypertension in comparison to drug therapy, sham biofeedback, no intervention or other relaxation techniques.141

However, not all studies have been unsupportive. A review of 9 randomized trials concluded that the regular use of transcendental meditation significantly reduced both systolic and diastolic blood pressure compared to a control.126Similarly, an analysis of 17 randomized controlled trials of various relaxation therapies found that only transcendental meditation resulted in significant reductions in blood pressure. Biofeedback, progressive muscle relaxation, and stress management training produced no such benefit.127In addition, a trial of 86 patients with hypertension suggested that daily, music-guided slow breathing reduced systolic blood pressure measured over a 24-hour period.143

Prehypertension is a condition where blood pressure is elevated above what is considered normal, but not the level of a hypertension diagnosis. A small randomized trial involving 43 patients with prehypertension showed that heart rate variability feedback reduced systolic blood pressure compared to slow abdominal breathing and control groups.148