Introduction
Most people cannot tell when their blood pressure is high, which is why
hypertension is called the “silent killer.” 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
a major cause 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 that pressure in the hose should be discharged after use. Many people, however, leave the hose with full pressure after using it. This rather common practice does not produce any immediate consequences. The hose does not develop leaks at the seams or burst outright on the first occasion it is left 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 develop and show leaks.
When human blood vessels are exposed to constant high pressure, a similar process is set in motion. Blood pressure that elevates to, for example, a reading of 220/170 (systolic pressure/diastolic pressure), which is quite common during certain physical activities such as weight lifting, do no harm. Only when excessive pressure is sustained do blood vessel linings begin to be injured and undergo the unhealthy changes known as atherosclerosis.
Although it is important to lower blood pressure, only rarely does it need to be lowered instantly. In most situations, a person has plenty of time to work on bringing down blood pressure. However, this does not mean that one should ignore it. Over time, high blood pressure can damage nearly every organ in the body.
The best way to determine one’s 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 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 that may have been caused by stress, for example. To record an accurate number, all measurements must be included in the 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 also makes a large contribution.
Lifestyle changes, such as quitting cigarettes, losing weight, and increasing exercise, can dramatically reduce blood pressure. One study found that engaging in aerobic exercise sixty to ninety minutes weekly may be sufficient for producing maximum benefits. Another study found that taking ten-minute brisk walks four times per day significantly improves blood pressure.
For many years doctors advised persons with hypertension to cut down on salt in the diet. Today, however, the value of this dietary change has undergone significant questioning. Considering how rapidly knowledge is evolving, it is suggested that one consult a physician to learn the latest recommendations.
If lifestyle changes fail to reduce blood pressure, or if one cannot make these alterations, many effective drugs are available. Sometimes experimentation with a few drugs helps in finding the most effective one.
Principal Proposed Natural Treatments
There are no herbs or supplements for hypertension with solid scientific support. However, the supplement coenzyme Q10 and extracts from the herb Stevia rebaudiana have shown some promise in preliminary trials.
Coenzyme Q
10. The supplement coenzyme Q10
(CoQ10) has shown promise as a treatment for high blood pressure,
but the evidence that it works is not strong. An eight-week, double-blind,
placebo-controlled study of fifty-nine men already taking medication for high
blood pressure found that 120 milligrams (mg) daily of CoQ10 reduced
blood pressure by about 9 percent compared with placebo. In addition, a
twelve-week, double-blind, placebo-controlled study of eighty-three people with
isolated systolic hypertension (a type of high blood pressure in which only the
“top” number is high) found that the use of CoQ10 at a dose of 60 mg
daily improved blood pressure measurements to a similar extent.
Also, in a twelve-week, double-blind, placebo-controlled trial of seventy-four people with diabetes, the use of CoQ10 at a dose of 100 mg twice daily significantly reduced blood pressure compared with placebo. Antihypertensive effects were also seen in earlier smaller trials, but most of them were not double-blind, so they mean little.
Stevia rebaudiana. The herb Stevia rebaudiana is best known as a sweetener. Its active ingredients are known as steviosides. In a one-year, double-blind, placebo-controlled study of 106 people in China with moderate hypertension (approximate blood pressure of 165/103), steviosides at a dose of 250 mg three times daily reduced blood pressure by approximately 10 percent. Full benefits took months to develop. However, this study is notable for finding no benefits in the placebo group. This is unusual and tends to cast doubt on the results.
Benefits also were reported in a two-year, double-blind, placebo-controlled study, also in China, of 174 people with milder hypertension (average initial blood pressure of approximately 150/95). This study used twice the dose of the previous study: 500 mg three times daily. A reduction in blood pressure of approximately 6 to 7 percent was seen in the treatment group compared with the placebo group, beginning within one week and enduring throughout the two years of the study. At the end of the study, 34 percent of those in the placebo group showed heart damage from high blood pressure (left ventricular hypertrophy), while only 11.5 percent of the stevioside group did, a difference that was statistically significant. No significant adverse effects were seen. However, once again, no benefits were seen in the placebo group. This is a red flag for problems in study design. Furthermore, a study by an independent set of researchers failed to replicate these findings.
Another study involving people with diabetes and healthy persons found that
stevia, at a dose of 250 mg three times daily, had no
significant effect on blood pressure after three months of treatment. A study by
an independent set of researchers failed to replicate these findings.
Relaxation therapies. Although it seems intuitive that relaxation
should lower blood pressure, the evidence for the benefits of relaxation
therapies for treating hypertension is far from convincing.
In a review of twenty-five studies investigating various relaxation therapies
(totaling 1,198 participants), researchers found that those studies employing a
control group reported no significant effect on lowering blood pressure compared
to sham (placebo) therapies.
More specifically, biofeedback is widely advocated for
treating hypertension. However, in an analysis of twenty-two studies, real
biofeedback when used alone was found to be no more effective than sham (fake)
biofeedback. A subsequent review of thirty-six 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.
However, some studies have been supportive. A review of nine randomized trials
concluded that the regular use of Transcendental Meditation significantly
reduced both systolic and diastolic blood pressure compared to a control.
Similarly, an analysis of seventeen 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. In addition, a trial of eighty-six persons with hypertension
suggested that daily, music-guided, slow breathing reduced systolic blood pressure
measured in a twenty-four-hour period.
Other Proposed Natural Treatments
The Iranian herb Achillea wilhelmsii was tested in a
double-blind trial of sixty men and women with mild hypertension. The results
showed that treatment with an A. wilhelmsii extract significantly
reduced blood pressure readings. Also, in a double-blind study of forty-three men
and women with hypertension, the use of a proprietary Ayurvedic herbal combination
containing Terminali arjuna and about forty other herbs proved
almost as effective for controlling blood pressure as the drug methyldopa.
Although the research record is mixed, it appears that fish oil may
reduce blood pressure, at least slightly. Fish oil contains two major active
ingredients, DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). Some
evidence suggests that it is the DHA in fish oil, not the EPA, that is responsible
for this benefit.
Several studies have found that glucomannan, a dietary fiber derived
from the tubers of Amorphophallus konjac, may improve high blood
pressure. Other forms of fiber also may be helpful.
Milk fermented by certain probiotics (friendly bacteria) may provide a small blood-pressure-lowering effect. Also, growing evidence supports the use of a green coffee bean extract for high blood pressure. Three preliminary double-blind studies found that chocolate (high in polyphenols) might help mild hypertension. A review including several additional studies drew a similar conclusion.
Numerous studies have found weak evidence that garlic lowers blood pressure slightly, perhaps 5 to 10 percent more than placebo. It remains unclear whether garlic supplements can help persons with high blood pressure safely eliminate or avoid antihypertensive medications.
People who are deficient in calcium may be at great risk of developing high blood pressure. Among people who already have hypertension, increased intake of calcium might slightly decrease blood pressure, according to some studies. In an extremely large, randomized, placebo-controlled trial involving 36,282 postmenopausal women, 1,000 mg of calcium plus 400 international units of vitamin D given daily did not significantly reduce blood pressure in seven years in women with or without hypertension. Weak evidence hints that the use of calcium by pregnant women might reduce the risk of hypertension in their children. Also, study results are mixed on whether magnesium or potassium supplements can improve blood pressure. At most, the benefit is likely quite small.
In a thirty-day, double-blind, placebo-controlled study of thirty-nine people
taking medications for hypertension, treatment with 500 mg of vitamin C
daily reduced blood pressure by about 10 percent. Smaller benefits were seen in
studies of people with normal blood pressure or borderline hypertension. One
double-blind study compared 500, 1,000, and 2,000 mg of vitamin C and found an
equivalent level of benefit in all three groups. (Because of the lack of a placebo
group, this study cannot be used as proof of effectiveness, only as a
demonstration of the equivalence of the doses.) However, other studies have failed
to find evidence of benefit with vitamin C. This mixed evidence suggests, on
balance, that if vitamin C does have any blood-pressure-lowering effect, it is at
most quite modest.
Unexpectedly, one study found that a combination of vitamin C (500 mg daily)
and grape seed oligomeric proanthocyanidins (1,000 mg daily) slightly increased
blood pressure. Whether this was a fluke of statistics or a real combined effect
remains unclear.
Other studies suggest possible benefit with the Ayurvedic herb Eclipta alba (also known as Bhringraja or Keshraja), beta-hydroxy-beta-methylbutyrate, theanine from black tea, blue-green algae products, chitosan, concord grape juice, garlic, gamma-aminobutyric acid, various forms of the herb hawthorn, kelp, lipoic acid combined with carnitine, quercetin, Salvia hispanica (a grain), and sweetie fruit (a hybrid between grapefruit and pummelo, high in citrus bioflavonoids). However, the supporting evidence cannot be considered reliable for any of these treatments.
There is mixed evidence on whether soy protein and its associated isoflavones are helpful for blood pressure. A comprehensive review of studies investigating the influence of phytoestrogens (including soy) on blood pressure found no meaningful effect. However, another review found that soy protein alone could significantly reduce blood pressure.
Three small, double-blind, placebo-controlled studies found evidence that melatonin may slightly reduce nighttime blood pressure. Getting adequate vitamin D may help prevent the development of hypertension. The vitamin folate may help decrease blood pressure (and might provide other heart-healthy effects) in smokers.
The herbs astragalus, barberry, Coleus forskohliibacailin, hibiscus, maitake, maca, and olive leaf, and the supplements beta-carotene, Cordyceps, flaxseed oil, royal jelly, and taurine, are sometimes recommended for high blood pressure, but there is no meaningful evidence that they work. Also, reducing homocysteine with B vitamins does not appear to reduce blood pressure in healthy people with high homocysteine.
One study was quoted as having showed that a traditional Chinese herbal formula
can reduce blood pressure, but the study actually failed to find any effect on
blood pressure. In a review of twenty-six published studies examining the
effectiveness of Tai Chi for high blood pressure, 85 percent demonstrated a
reduction in blood pressure. However, only five of these twenty-six studies were
of acceptable quality.
A substantial study (192 participants) failed to find acupuncture helpful for high blood pressure. However, another study, this one enrolling 160 people, did report benefit, but the study was small and had problems in its use of statistics. In a review of eleven randomized-controlled trials on the subject, researchers determined that acupuncture’s ability to lower blood pressure remains inconclusive.
The alternative therapies hatha yoga, qigong, and
Tai Chi have shown some potential benefit for high blood pressure, the mechanism
of action probably being similar for each. A later review of multiple studies
investigating the effectiveness of self-practiced qigong, for example, concluded
that this therapy was more effective at lowering blood pressure than no- treatment
controls. However, it was no more effective than standard treatments for
hypertension: antihypertensive medications or conventional exercise.
In a twelve-week study of 140 men and women with stage I hypertension, chiropractic spinal manipulation plus dietary change did not produce any greater benefit than dietary change alone. For many years, the American Heart Association and other major foundations have recommended reducing saturated fat and increasing carbohydrates in one’s diet. However, growing evidence suggests that it is preferable to keep carbohydrate levels relatively low while replacing saturated fat with monounsaturated fats such as olive oil.
Herbs and Supplements to Use Only with Caution
There is one highly credible case report of severe, dangerous hypertension caused by consumption of isoflavones made from soy during the course of a clinical trial on this supplement. This is most likely a rare, highly individual response, but if it could occur with one person, it also could occur with another.
As noted, in one study, a combination of vitamin C and grape seed oligomeric proanthocyanidins mildly increased blood pressure. In another study, the use of vitamin E raised blood pressure in people with type 2 diabetes.
The herb
Citrus aurantium
(bitter orange) may increase blood pressure. In addition, various herbs and supplements may interact adversely with drugs used to treat hypertension.
Bibliography
Anderson, J. W., C. Liu, and R. J. Kryscio. “Blood Pressure Response to Transcendental Meditation.” American Journal of Hypertension 21 (2008): 310–16. Print.
Erkkila, A. T., et al. “Effects of Fatty and Lean Fish Intake on Blood Pressure in Subjects with Coronary Heart Disease Using Multiple Medications.” European Journal of Nutrition 47 (2008): 319–28. Print.
Greenhalgh, J., R. Dickson, and Y. Dundar. “Biofeedback for Hypertension.” Journal of Hypertension 28 (2010): 644–52. Print.
Heather, O. D., et al. “Relaxation Therapies for the Management of Primary Hypertension in Adults.” Cochrane Database of Systematic Reviews (2008): CD004935. EBSCO DynaMed Systematic Literature Surveillance. Web. 27 Jan. 2016.
“High Blood Pressure.” MedlinePlus. US Natl. Lib. of Medicine, 6 Oct. 2015. Web. 27 Jan. 2016.
Hooper, L., et al. “Flavonoids, Flavonoid-Rich Foods, and Cardiovascular Risk.” American Journal of Clinical Nutrition 88 (2008): 38–50. Print.
Lee, H., et al. “Acupuncture for Lowering Blood Pressure.” American Journal of Hypertension 22 (2009): 122–28. Print.
Margolis, K. L., et al. “Effect of Calcium and Vitamin D Supplementation on Blood Pressure.” Hypertension 52 (2008): 847–55. Print.
Modesti, P. A., et al. “Psychological Predictors of the Antihypertensive Effects of Music-Guided Slow Breathing.” Journal of Hypertension 28 (2010): 1097-1103.
Ried, K., et al. “Effect of Garlic on Blood Pressure.” BMC Cardiovascular Disorders 9 (2008): 13. Print.
Rogers, P. J., et al. “Time for Tea: Mood, Blood Pressure, and Cognitive Performance Effects of Caffeine and Theanine Administered Alone and Together.” Psychopharmacology 195 (2008): 569–77. Print.
Wahabi, H. A., et al. “The Effectiveness of Hibiscus sabdariffa in the Treatment of Hypertension.” Phytomedicine 17 (2010): 83–86. Print.
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