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What are the symptoms?Essential hypertension is usually without symptoms until complications develop. The symptoms of complications depend on the organs involved. Dietary changes that may be helpfulPrimitive societies exposed to very little salt suffer from little or no hypertension.1 Salt (sodium chloride) intake has also been definitively linked to hypertension in western societies.2 Reducing salt intake in the diet lowers blood pressure in most people.3 The more salt is restricted, the greater the blood pressure-lowering effect.4 Individual studies sometimes come to differing conclusions about the relationship between salt intake and blood pressure, in part because blood pressure-lowering effects of salt restriction vary from person to person, and small to moderate reductions in salt intake often have minimal effects on blood pressure—particularly in young people and in those who do not have hypertension. Nonetheless, dramatic reductions in salt intake are generally effective for many people with hypertension. With the prevalence of salted processed and restaurant food, simply avoiding the salt shaker no longer leads to large decreases in salt intake for most people. Totally eliminating salt is more effective, but is quite difficult to achieve. Moreover, while an overview of the research found “There is no evidence that sodium reduction presents any safety hazards,”5 reports of short-term paradoxical increases in blood pressure in response to salt restriction have occasionally appeared.6 Therefore, people wishing to use salt reduction to lower their blood pressure should consult with a doctor. Vegetarians have lower blood pressure than do people who eat meat.7 This occurs partly because fruits and vegetables contain potassium—a known blood pressure-lowering mineral.8 The best way to supplement potassium is with fruit, which contains more of the mineral than do potassium supplements. However, fruit contains so much potassium that people taking “potassium-sparing”diuretics can consume too much potassium simply by eating several pieces of fruit per day. Therefore, people taking potassium-sparing diuretics should consult the prescribing doctor before increasing fruit intake. In the Dietary Approaches to Stop Hypertension (DASH) trial, increasing intake of fruits and vegetables (and therefore fiber) and reducing cholesterol and dairy fat led to large reductions in blood pressure (in medical terms, 11.4 systolic and 5.5 diastolic) in just eight weeks.9 Even though it did not employ a vegetarian diet itself, the outcome of the DASH trial supports the usefulness of vegetarian diets because diets employed by DASH researchers were related to what many vegetarians eat. The DASH trial also showed that blood pressure can be significantly reduced in hypertensive people (most dramatically in African Americans) with diet alone, without weight loss or even restriction of salt.10 Nonetheless, restricting salt while consuming the DASH diet has lowered blood pressure even more effectively than the use of the DASH diet alone.11 Sugar has been reported to increase blood pressure in animals12 and humans in short-term trials.13 Though the real importance of this experimental effect remains unclear,14 some doctors recommend that people with high blood pressure cut back on their intake of sugar. Right after consuming caffeine from coffee or tea, blood pressure increases briefly.15 16 In trials lasting almost two months on average, coffee drinking has led to small increases in blood pressure.17 The effects of long-term avoidance of caffeine (from coffee, tea, chocolate, cola drinks, and some medications) on blood pressure remain unclear. A few reports have even claimed that long-term coffee drinkers tend to have lower blood pressure than those who avoid coffee.18 Despite the lack of clarity in published research, many doctors tell people with high blood pressure to avoid consumption of caffeine. Several double-blind trials have shown that adding 6.5–7 grams of fiber per day to the diet for several months leads to reductions in blood pressure.19 20 21 However, other trials have not found fiber helpful in reducing blood pressure.22 23 The reason for these discrepant findings is not clear. Food allergy was reported to contribute to high blood pressure in a study of people who had migraine headaches.24 In that report, all 15 people who also had high blood pressure experienced a significant drop in blood pressure when put on a hypoallergenic diet. People who suffer migraine headaches and have hypertension should discuss the issue of allergy diagnosis and elimination with a doctor. Reusing vegetable oils for frying, especially oils with high concentrations of unsaturated fatty acids (such as sunflower or safflower oil) has been associated with an increased risk of high blood pressure.25 Presumably, this increased risk is due to some of the degradation products (such as lipid peroxides or polymers) that result from the excessive heating of these oils. Frying with more stable oils, such as olive oil, is not associated with an increased risk of high blood pressure. Exposure to lead and other heavy metals has been linked to high blood pressure in some,26 but not all, research.27 If other approaches to high blood pressure prove unsuccessful, it makes sense for people with hypertension to have their body’s burden of lead evaluated by a healthcare professional. In a double-blind trial, supplementation with a tomato extract significantly lowered both systolic and diastolic blood pressure, compared with a placebo, in people with hypertension.28 The amount of extract used was 250 mg per day (providing 15 mg per day of lycopene plus other carotenoids) for eight weeks. Lifestyle changes that may be helpfulSmoking is particularly injurious for people with hypertension.29 The combination of hypertension and smoking greatly increases the risk of heart disease–related sickness and death. All people with high blood pressure need to quit smoking. Consumption of more than about three alcoholic beverages per day appears to increase blood pressure.30 Whether one or two drinks per day meaningfully increases blood pressure remains unclear. Daily exercise can lower blood pressure significantly.31 A 12-week program of Chinese T’ai Chi was reported to be almost as effective as aerobic exercise in lowering blood pressure.32 Progressive resistance exercise (e.g., weight lifting) also appears to help reduce blood pressure.33 At the same time, blood pressure has been known to increase significantly during the act of lifting heavy weights; for this reason, people with sharply elevated blood pressure, especially those with cardiovascular disease, should approach heavy strenuous resistance exercise with caution. In general, people over 40 years of age should consult with their doctors before starting any exercise regimen. Most people with high blood pressure are overweight. Weight loss lowers blood pressure significantly in those who are both overweight and hypertensive.34 In fact, reducing body weight by as little as ten pounds can lead to a significant reduction in blood pressure.35 Weight loss appears to have a stronger blood pressure-lowering effect than dietary salt restriction.36 Other therapiesHealthcare practitioners may also recommend lifestyle modifications, such as moderate weight reduction and a decrease in salt intake. Though essential hypertension has no cure, treatment can modify its course and reduce the risk of complications. Vitamins that may be helpfulBoth preliminary37 38 39 and double-blind40 41 trials have reported that supplementation with Coenzyme Q10 (CoQ10) leads to a significant decrease in blood pressure in people with hypertension. Much of this research has used 100 mg of CoQ10 per day for at least ten weeks. EPA and DHA, the omega-3 fatty acids found in fish oil, lower blood pressure, according to an analysis of 31 trials.42 The effect was dependent on the amount of omega-3 oil used, with the best results occurring in trials using unsustainably high levels: 15 grams per day—the amount often found in 50 grams of fish oil. Although results with lower intakes were not as impressive, trials using over 3 grams per day of omega-3 (as typically found in ten 1,000 mg pills of fish oil) also reported significant reductions in blood pressure. One double-blind trial reported that DHA had greater effects on blood pressure than EPA or mixed fish oil supplements.43 DHA is now available as a supplement separate from EPA. Potassium supplements in the amount of at least 2,400 mg per day lower blood pressure, according to an analysis of 33 trials.44 However, potassium supplements greater than 100 mg per tablet require a prescription, and the low-dose potassium supplements available without a prescription can irritate the stomach if taken in large amounts. Moreover, some people, such as those taking potassium-sparing diuretics, should not take potassium supplements. Therefore, the use of potassium supplements for lowering blood pressure should only be done under the care of a doctor. Some,45 but not all,46 trials show that magnesium supplements—typically 350–500 mg per day—lower blood pressure. Magnesium appears to be particularly effective in people who are taking potassium-depleting diuretics.47 Potassium-depleting diuretics also deplete magnesium. Therefore, the drop in blood pressure resulting from magnesium supplementation in people taking these drugs may result from overcoming a mild magnesium deficiency. Calcium supplementation—typically 800–1,500 mg per day—may lower blood pressure. However, while an analysis of 42 trials reported that calcium supplementation led to an average drop in blood pressure that was statistically significant, the actual decrease was small (in medical terms, a drop of 1.4 systolic over 0.8 diastolic pressure).48 Results might have been improved had the analysis been limited to studies of people with hypertension, since calcium has almost no effect on the blood pressure of healthy people. In the analysis of 42 trials, effects were seen both with dietary calcium and with use of calcium supplements. A 12-week trial of 1,000 mg per day of calcium accompanied by blood pressure monitoring is a reasonable way to assess efficacy in a given person. In a double-blind trial, women with low blood levels of vitamin D (measured as 25-hydroxyvitamin D3) were given a calcium supplement, plus either 800 IU of vitamin D per day or a placebo for eight weeks. Compared with the placebo, vitamin D significantly reduced systolic blood pressure by an average of 9.3%, but did not affect diastolic blood pressure.49 In a double-blind study, supplementation with 2 mg of sustained-release melatonin each night for four weeks significantly reduced nighttime systolic blood pressure, compared with a placebo, in people with nocturnal hypertension.50 Normally, blood pressure declines at night. People with hypertension who do not have this nighttime blood pressure decline are at increased risk of developing and dying from heart disease. Melatonin supplementation may therefore be beneficial for this subgroup of people with hypertension. In a double-blind study of postmenopausal women, supplementing with 10 grams of soy protein twice a day for six weeks significantly reduced diastolic blood pressure by an average of 5 mm Hg, compared with a diet not containing soy protein.51 In another study, men and women with mild to moderate hypertension consumed 500 ml (approximately 16 ounces) of soy milk or cow's milk twice a day for three months. After three months, the average systolic blood pressure had decreased by 18.4 mm Hg in the soy group, compared with 1.4 mm Hg in the cow's milk group. The reductions in diastolic blood pressure were 15.9 mm Hg with soy milk and 3.7 mm Hg with cow's milk.52 In another study of people with hypertension who were consuming a low-protein, low-fiber diet, supplementing with a combination of soy protein and psyllium (a fiber source) lowered systolic blood pressure by an average of 5.9 mm Hg.53 The blood pressure reduction with soy protein alone or with fiber alone was less pronounced than that with combination treatment. Other research has also shown a blood pressure–lowering effect of soy protein.54 55 Five double-blind trials have found that vitamin C supplementation reduces blood pressure, but the reduction was statistically significant in only three of the five, and in most cases reductions were modest.56 57 Some doctors recommend that people with elevated blood pressure supplement with 1,000 mg vitamin C per day. In a double-blind study of people with high blood pressure, 200 IU of vitamin E per day taken for 27 weeks was significantly more effective than a placebo at reducing both systolic and diastolic blood pressure.58 This study was done in Iran, and it is not clear whether the results would apply to individuals consuming a Western diet. A deficiency of the amino acid taurine, is thought by some researchers to play an important role in elevating blood pressure in people with hypertension.59 Limited research has found that supplementation with taurine lowers blood pressure in animals60 and in people (at 6 grams per day),61 possibly by reducing levels of the hormone epinephrine (adrenaline). The amino acid arginine is needed by the body to make nitric oxide, a substance that allows blood vessels to dilate, thus leading to reduced blood pressure. Intravenous administration of arginine has reduced blood pressure in humans in some reports.62 In one controlled trial, people not responding to conventional medication for their hypertension were found to respond to a combination of conventional medication and oral arginine (2 grams taken three times per day.)63 Herbs that may be helpfulIn a double-blind trial, people with mild hypertension took a tincture of Achillea wilhelmsii, an herb used in traditional Persian medicine.64 Participants in the trial used 15–20 drops of the tincture twice daily for six months. At the end of the trial, participants experienced significant reductions in both systolic and diastolic blood pressure compared to those who took placebo. No adverse effects were reported. Garlic has a mild blood pressure-lowering effect, according to an analysis of ten double-blind trials.65 All of these trials administered garlic for at least four weeks, typically using 600–900 mg of garlic extract per day. Onion—closely related to garlic—may also have a mild blood pressure-lowering effect, according to preliminary research.66 Two controlled clinical trials have shown that hibiscus can lower blood pressure. In one, people with high blood pressure who went off their medications were given either 2 teaspoons (5 to 6 grams) Hibiscus sabdariffa infused in 1 cup (250 ml) water or black tea three times per day.67 After 12 days the hibiscus group had significantly lower blood pressure than the black tea group. In another trial 10 grams of Hibiscus sabdariffa tea was compared to the drug captopril for four weeks in people with high blood pressure.68 Blood pressures fell an equal amount in both groups, suggesting this herbal tea may be as potent as some blood pressure medications. European mistletoe (Viscum album) has reduced headaches and dizziness associated with high blood pressure, according to preliminary research.69 Mistletoe may be taken as 0.5 ml tincture three times per day.70 The blood pressure-lowering effect of mistletoe is small and may take weeks to become evident. Due to possible serious side effects, European mistletoe should only be taken under the careful supervision of a physician trained in its use. Indian snakeroot (Rauwolfia serpentina) contains powerful alkaloids, including reserpine, that affect blood pressure and heart function. Indian snakeroot has been used traditionally to treat hypertension, especially when associated with stress and anxiety.71 Due to possible serious side effects, Indian snakeroot should only be taken under the careful supervision of a physician trained in its use. In animal studies oleuropein, one of the constituents of olive leaf, has decreased blood pressure and dilated arteries surrounding the heart, when given by injection or intravenously.72 Olive leaf has been used traditionally to treat people with hypertension,73 but controlled human trials are needed before a blood pressure-lowering effect can be established. A double-blind trial reported that reishi mushrooms significantly lowered blood pressure in humans.74 The trial used a concentrated extract of reishi (25:1) in the amount of 55 mg three times per day for four weeks. It is unclear from the clinical report how long it takes for the blood pressure-lowering effects of reishi to be measured. Hawthorn leaf and flower extracts have been reported to have a mild blood pressure–lowering effect in people with early stage congestive heart failure.75 In a double-blind study, supplementation with a hawthorn extract significantly decreased diastolic blood pressure in people with type 2 diabetes. The amount used was 1,200 mg per day of an extract standardized to 2.2% flavonoids corresponding to 6 per day of dried flowering tops.76 Human trials investigating the use of Coleus forskohlii in blood pressure reduction have yet to be conducted. However, forskolin, the active ingredient in Coleus forskohlii, has lowered blood pressure in a small, preliminary trial with people suffering from cardiomyopathy.77 Extracts of coleus standardized to contain 15–20% forskolin are available, but further trials are needed to determine effective levels for treating people with hypertension. Most herbal reference books suggest that ginseng should not be used by people with hypertension. However, the results of a preliminary trial suggest that red ginseng root (Panax ginseng radix rubra) has either no effect on, or may actually slightly lower, blood pressure in hypertensive people.78 However, many herbalists continue to believe that people with hypertension should avoid Asian ginseng and American ginseng, and, while not a true ginseng, Siberian ginseng (eleuthero) as well. Holistic approaches that may be helpfulAnxiety in men (but not women) has been linked to development of hypertension.79 Several research groups have also shown a relationship between job strain and high blood pressure in men.80 81 82 Some researchers have tied blood pressure specifically to suppressed aggression.83 Although some kind of relationship between stress and high blood pressure appears to exist, the effects of treatment for stress remain controversial. An analysis of 26 trials reported that reductions in blood pressure caused by biofeedback or meditation were no greater than those seen with placebo.84 Though some stress management interventions have not been helpful in reducing blood pressure,85 86 those trials that have reported promising effects have used combinations of yoga, biofeedback, and/or meditation.87 88 89 Some doctors continue to recommend a variety of stress-reducing measures, sometimes tailoring them to the needs and preferences of the person seeking help. Preliminary laboratory studies in animals90 and humans91 92 93 suggest that acupuncture may help regulate blood pressure. Most,94 95 96 97 98 99 but not all,100 preliminary trials also suggest that acupuncture may be an effective way to lower blood pressure. Whether blood pressure goes back up after acupuncture is discontinued remains an unsettled question. Auricular (ear) acupressure has been reported to be an effective treatment for hypertension,101 102 103 though in one case the improvement was not significantly better than use of traditional herbal medicines.104 Spinal manipulation may lower blood pressure (at least temporarily) in healthy people, according to most preliminary105 106 107 and controlled108 trials. However, some research suggests the effect is no better than the blood pressure-lowering effect of sham (“fake”) manipulation.109 In hypertensive people, temporary decreases in blood pressure have also been reported after spinal manipulation.110 111 112 However, most,113 114 115 but not all,116 trials suggest that manipulation produces only short-term decreases in blood pressure in hypertensive people. References (To view, roll mouse over the "References" heading; to hide, click on the heading) Copyright © 2008 Healthnotes, Inc. All rights reserved. www.healthnotes.com Learn more about Healthnotes, the company. Learn more about the authors of Healthnotes. The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2009. |
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