• Borderline high blood pressure (prehypertension): 130–139/85–89 mm Hg
• Mild high blood pressure (stage 1): 140–159/90–99 mm Hg
• Moderate high blood pressure (stage 2): 160–179/100–109 mm Hg
• Severe high blood pressure (stage 3): 180 or over/110 or over mm Hg
Elevated blood pressure (hypertension) is a major risk factor for a heart attack or stroke. In fact, it is generally regarded as the most significant risk factor for a stroke. More than 60 million Americans have high blood pressure (high BP), including more than half (54.3%) of all Americans ages 65 to 74 and almost three-quarters (71.8%) of all American blacks in the same age group.
Individuals with a normal diastolic pressure (under 85 mm Hg) but significantly elevated systolic pressure (over 158 mm Hg) have what is termed isolated systolic hypertension. It is usually an indication of significant hardening of the aorta and carries with it a twofold increase in cardiovascular death rates when compared with a systolic pressure under 130 mm Hg).
Causes
High BP is most often the result of factors that affect the degree of blood vessel constriction and fluid volume. Although genetic factors play a role, there is little debate that dietary, lifestyle, psychological, and environmental factors are the underlying causes in most cases of high BP. Dietary factors include excessive calorie consumption; high sodium-to-potassium ratio; low-fiber, high-sugar diet; high consumption of saturated fat and low consumption of omega-3 fatty acids; and a diet low in calcium, magnesium, and vitamin C. Important lifestyle factors that may cause high BP include stress, lack of exercise, and smoking. The dietary factor that has received the greatest attention is salt intake. Between 40 and 60% of people with high blood pressure are salt-sensitive (as discussed later).
Exposure to heavy metals such as lead, mercury, cadmium, and arsenic may also be a significant factor in some patients. The kidneys take the primary role in the elimination of heavy metals, so these metals concentrate there and disrupt the kidneys’ ability to regulate the body’s fluid volume; this disruption results in sodium and water retention. Although studies of blood lead levels have not consistently shown an association with high blood pressure, it is important to point out that blood lead levels reflect primarily acute exposure.1–3 Studies looking at bone lead levels, for example, have clearly documented that exposure to heavy metals is associated with an increased risk for high BP.4
Classification of Blood Pressure
• Optimal: systolic under 120, diastolic under 80 mm Hg
• Normal: systolic 120–129, diastolic 80–85 mm Hg
• Borderline high blood pressure (prehypertension): systolic 130–139, diastolic 85–89 mm Hg
• Mild high blood pressure (stage 1): systolic 140–159, diastolic 90–99 mm Hg
• Moderate high blood pressure (stage 2): systolic 160–179, diastolic 100–109 mm Hg
• Severe high blood pressure (stage 3): systolic 180 or over, diastolic 110 mm Hg or over
“White-Coat Hypertension”
“White-coat hypertension” has been defined as the elevation of blood pressure in a clinic or doctor’s office only. The prevalence of white-coat hypertension may be as high as 20 to 45% of people diagnosed as having high BP.5 It appears to be more frequent in women and older patients. The current conventional wisdom among naturopathic physicians is to treat white-coat hypertension as if it were real, as results from recent studies suggest that it is not an innocent phenomenon.6,7 To rule out white-coat hypertension a patient wears a device to measure blood pressure continuously (ambulatory blood pressure monitoring).8 In patients with confirmed white-coat hypertension, drug treatment is usually not indicated; instead, treatment should consist of counseling for better stress management, lifestyle and dietary modification, weight reduction, regular exercise, smoking cessation, and correction of blood sugar and cholesterol elevations.
High Blood Pressure
Therapeutic Considerations
Because more than 80% of patients with high BP are in the borderline-to-moderate range, most cases of high BP can be brought under control through changes in diet and lifestyle. In fact, in head-to-head comparisons, many nondrug therapies such as diet, exercise, and relaxation therapies have proved superior to drugs in cases of borderline to mild high BP. For moderate through severe hypertension, drug therapy may be necessary. Ideally, drug treatment should be used only until the dietary, lifestyle, and supplement strategies take hold. However, sometimes long-term drug therapy is required.
Lifestyle
High BP is closely related to lifestyle and dietary factors. The important lifestyle factors include smoking, stress, and lack of exercise. The most important dietary factors include excessive calorie intake; high sodium-to-potassium ratio; low-fiber, high-sugar diet; high consumption of saturated fat and low consumption of essential fatty acids; a diet low in calcium, magnesium, or vitamin C; and excessive alcohol or caffeine intake.
In addition to the following discussions, several of these dietary and lifestyle factors are also discussed in the chapter “Heart and Cardiovascular Health,” because the health of the arteries is critical to maintaining normal blood pressure.
Stress
Stress can be the cause of high BP in many instances, although, as in other health conditions, this has more to do with the response to and processing of stress than with stress itself. Relaxation techniques such as deep breathing exercises, biofeedback, transcendental meditation, yoga, progressive muscle relaxation, and hypnosis have all been shown to have some value in lowering blood pressure.9 Although the effect may be only modest in some cases, a stress reduction technique is nonetheless a necessary component in a natural blood-pressure-lowering program.
One of the most powerful ways to manage stress and have more energy is diaphragmatic breathing. Regular, short sessions of slow and regular diaphragmatic breathing have also been shown to lower blood pressure in several studies.10–12 In one study, volunteers with normal blood pressure were taught shallow breathing. Measurement of the amount of sodium and potassium excreted in the urine indicated that shallow breathing led to the retention of sodium in the body. It was suggested that this breathing pattern may play a causative role in some cases of high BP.13 In contrast, deep, slow breathing (six breaths per minute) has been shown to improve oxygen saturation, exercise tolerance, and blood pressure monitoring by the body’s pressure sensors.14
RESPeRATE is a medical device that interactively guides the user toward slow and regular breathing by voluntarily synchronizing respiration to musical tones. When used for 15 minutes per day, this device can lead to significant reduction in blood pressure. In one eight-week study, systolic BP was reduced by 10.0 mm Hg and diastolic BP by 3.6 mm Hg in the subjects who used RESPeRATE, but not in the controls; greater BP reduction was observed with increased compliance with device usage.15
Exercise
Population-based studies have consistently demonstrated an inverse association between physical activity (or fitness) and blood pressure. The more fit a person is, the less likely he or she is to have high BP. In addition, clinical trials involving hypertensive patients have clearly established regular exercise as an effective treatment for high BP.16–20 Although it is generally thought that the greater the intensity of aerobic exercise, the greater the blood-pressure-lowering effect, recently it was shown that even as little as 20 minutes of mild to moderate aerobic exercise three times per week can lower blood pressure.20The degree of blood pressure reduction achieved by adopting a regular exercise program is typically in the range of 5 to 10 mm Hg for both the systolic and the diastolic readings. Patients with borderline and mild hypertension typically can bring blood pressure readings into the normal range with regular exercise.
Diet
The most important dietary goal for most patients with any form of high BP is achieving normal body weight. Weight loss can lead to significant improvement in and even complete elimination of the problem; it can also reduce the number of prescription drugs a person needs to take.21,22
Next to attaining ideal body weight, perhaps the most important dietary recommendation is to increase the proportion of plant foods in the diet. Vegetarians generally have lower blood pressure and a lower incidence of high BP and other cardiovascular diseases than nonvegetarians.23 Although dietary levels of sodium do not differ significantly between these two groups, a vegetarian’s diet typically contains more potassium, complex carbohydrates, beneficial oils, fiber, calcium, magnesium, and vitamin C and less saturated fat and refined carbohydrate; all of these factors have a favorable influence on blood pressure.
Increasing fruit and vegetable intake has been shown to lower blood pressure.24 This effect may be the result of increasing antioxidant concentrations. People with high BP have been shown to have increased oxidative stress, and dietary antioxidants have been shown to produce some benefits in high BP.25,26
The most useful foods for people with high BP include the following:
• Celery
• Garlic and onions
• Nuts and seeds or their oils
• Cold-water fish (e.g., salmon, mackerel)
• Green leafy vegetables, for their rich content of calcium and magnesium
• Whole grains and legumes
• Foods rich in vitamin C, such as broccoli and citrus fruits
• Foods rich in flavonoids, including berries, cherries, grapes, and red kidney beans
Celery is a particularly interesting recommendation for high BP. It contains 3-n-butylphthalide, a compound that has been found to lower blood pressure. In animals, a small amount of this compound lowered blood pressure by 12 to 14% and cholesterol by about 7%.27 The equivalent dose in humans can be supplied by about four to six ribs of celery. The research was prompted by the father of one of the researchers, who, after eating 1/4 lb of celery per day for one week, observed that his blood pressure had dropped from 158/96 to 118/82.
Garlic and onions are also important foods for lowering blood pressure. Although most recent research has focused on the cholesterol-lowering properties of garlic and onions, both have been shown to lower blood pressure in people with high BP. In addition, commercial garlic supplements may be of benefit. In a meta-analysis of published clinical trials of garlic preparations that included a total of 415 subjects, subjects who were given a dried garlic powder standardized to contain 1.3% alliin at a dosage of 600 to 900 mg per day (corresponding to 7.8 or 11.7 mg alliin, the equivalent of approximately 1.8 to 2.7 g fresh garlic per day) saw a typical drop of 11 mm Hg in systolic blood pressure and 5 mm Hg in diastolic blood pressure over a period of one to three months.28
The Dietary Approaches to Stop Hypertension (DASH) Diet
The Dietary Approaches to Stop Hypertension (DASH) clinical studies were funded by the National Heart, Lung, and Blood Institute to fully evaluate the efficacy of a system of dietary recommendations in the treatment of high BP. The DASH diet is rich in fruits, vegetables, and low-fat dairy foods and low in saturated and total fat. It is also low in cholesterol; high in dietary fiber, potassium, calcium, and magnesium; and moderately high in protein.
The first study showed that a diet rich in fruits, vegetables, and low-fat dairy products can reduce blood pressure in the general population and people with high BP.29 The original DASH diet did not require either sodium restriction or weight loss—the two traditional dietary tools to control blood pressure—to be effective.30 The second study from the DASH research group found that coupling the original DASH diet with sodium restriction is more effective than either the DASH diet alone or restricting sodium alone.31 In the first trial, the DASH diet produced a net blood pressure reduction of 11.4 and 5.5 mm Hg systolic and diastolic, respectively, in patients with high BP. In the second trial, sodium intake was also quantified at a “higher” intake of 3,300 mg per day, an “intermediate” intake of 2,400 mg per day, and a “lower” intake of 1,500 mg per day. Compared with the control diet, the DASH diet was associated with a significantly lower systolic blood pressure at each sodium level. The DASH diet with the lower sodium level led to a mean systolic blood pressure that was 7.1 mm Hg lower in participants without hypertension and 11.5 mm Hg lower in participants with hypertension. These results are clinically significant and indicate that a sodium intake below 1,500 mg per day can significantly and quickly lower blood pressure.
|
Components of the DASH Eating Plan |
||||
|
FOOD GROUP |
SERVINGS PER DAY |
SERVING SIZE |
EXAMPLES |
SIGNIFICANCE OF EACH FOOD GROUP IN THE DASH DIET |
|
Vegetables |
4–5 |
1 cup raw leafy vegetables |
Tomatoes, potatoes, carrots, peas, squash, broccoli, turnip greens, collards, kale, spinach, artichokes, sweet potatoes, beans |
Rich sources of potassium, magnesium, and fiber |
|
Fruits |
4–5 |
6 fl oz fruit juice |
Apricots, bananas, dates, oranges, orange juice, grapefruit, grapefruit juice, mangoes, melons, peaches, pineapples, prunes, raisins, strawberries, tangerines |
Important sources of potassium, magnesium, and fiber |
|
Low-fat or nonfat dairy foods |
2–3 |
8 fl oz milk |
Skim or 1% milk, skim or low-fat buttermilk, nonfat or low-fat yogurt, part-skim mozzarella cheese, nonfat cheese |
Major sources of calcium and protein |
|
Meats, poultry, and fish |
2 or less |
3 oz cooked meats, poultry, or fish |
Select only lean; trim away visible fats; broil, roast, or boil, instead of frying; remove skin from poultry |
Rich sources of protein and magnesium |
|
Nuts, seeds, and legumes |
4–5 per week |
1.5 oz or 1/3 cup nuts |
Almonds, filberts, mixed nuts, peanuts, walnuts, sunflower seeds, kidney beans, lentils |
Rich sources of energy, magnesium, potassium, protein, and fiber |
Potassium and Sodium
Considerable evidence indicates that a diet low in potassium and high in sodium is associated with high BP and plays a major role in the development of cancer and heart disease.32,33 There is overwhelming evidence that dietary sodium chloride (salt) is a major cause of raised blood pressure, and that a modest reduction in salt intake lowers blood pressure; this is predicted to reduce cardiovascular disease, as there is a direct relation between salt intake and cardiovascular risk.34 Conversely, a diet high in potassium and low in sodium is protective against these diseases. In the case of high BP, as evident in the second DASH study and others, this type of diet can be therapeutic.
It is a well-established fact that excessive consumption of dietary sodium chloride, coupled with diminished dietary potassium, is a common cause of high BP in many people. Some people are sensitive to salt and others are not, but as of 2012 there is no way to identify those who are salt sensitive except by restricting salt intake and seeing the effect. However, while salt restriction is important, numerous studies have shown that sodium restriction alone does not significantly improve blood pressure control in many cases—it must be accompanied by a high potassium intake. In a typical Western diet only 5% of sodium intake comes from the natural constituents in food. Prepared foods contribute 45% of the sodium intake, 45% is added during cooking, and another 5% is added as a condiment.
Most Americans have a potassium-to-sodium (K:Na) ratio of less than 1:2. Epidemiological and experimental research suggests that a dietary K:Na ratio greater than 5:1 is necessary to maintain health. However, even this level may not be optimal. A natural diet rich in fruits and vegetables can produce a K:Na ratio greater than 100:1, as most fruits and vegetables have a K:Na ratio of at least 50:1.
Many studies have now shown that increasing dietary potassium intake can lower blood pressure.35 In addition, several studies have shown that potassium supplementation alone can produce significant reductions in blood pressure in hypertensive subjects. In a meta-analysis of 33 randomized, controlled trials totaling 2,609 participants, potassium supplementation was associated with a reduction in mean systolic and diastolic blood pressure of 4.44 and 2.45 mm Hg, respectively. The effects of potassium supplementation appeared to be enhanced in subjects who had a high intake of sodium, indicating that potassium is important for prevention and treatment of high BP in those who are unable to reduce their intake of sodium. The dosage of potassium typically used in the studies ranged from 2.5 to 5 g per day.
In one study, 37 adults with mild hypertension received either 2.5 g per day of potassium, 2.5 g per day of potassium plus 480 mg per day of magnesium, or a placebo for eight weeks, and then were crossed over to receive one of the other treatments for another eight weeks and then crossed over again to receive the third treatment for an additional eight weeks.36 The potassium supplementation lowered systolic blood pressure an average of 12 mm Hg and diastolic blood pressure an average of 16 mm Hg. Interestingly, the addition of magnesium offered no further reduction in blood pressure; nonetheless, other studies have showed magnesium supplementation to be helpful (this is discussed later).
Potassium supplementation may be especially useful in the treatment of high BP in people older than 65, who often do not fully respond to BP-lowering drugs. In one double-blind study, 18 untreated elderly patients (average age 75 years) with a systolic blood pressure greater than 160 mm Hg or a diastolic blood pressure greater than 95 mm Hg, or both, were given either potassium chloride (2.5 g potassium) or a placebo each day for four weeks.37 After this relatively short treatment period, the group receiving the potassium experienced a drop of 12 mm Hg in systolic blood pressure and 7 mm Hg in diastolic blood pressure. These results compare quite favorably with the reduction of blood pressure produced by drug therapy, but without the side effects.38
Potassium supplements are available by prescription as well as over the counter. However, the FDA restricts the amount of potassium available in over-the-counter potassium supplements to a mere 99 mg per dose because of problems associated with high-dosage prescription potassium salts. Yet salt substitutes such as the popular brands NoSalt and Nu-Salt are, in fact, potassium chloride and provide 530 mg potassium per 1/6 tsp. Potassium salts are commonly prescribed in the dosage range of 1.5 to 3 g per day, but at these high dosages they can cause nausea, vomiting, diarrhea, and ulcers when given in pill form. These effects are not seen when potassium levels are increased through the diet or through the use of potassium-based salt substitutes. This difference highlights the advantages of using foods or food-based potassium supplements rather than pills to meet the human body’s high potassium requirements.
Potassium supplementation is relatively safe, except for patients with kidney disease. Their inability to excrete excess potassium may result in heart arrhythmias and other consequences of potassium toxicity. Potassium supplementation is also contraindicated when a patient is using any of a number of prescription medications including digitalis, potassium-sparing diuretics, and the ACE inhibitor class of antihypertensive drugs.
Caffeine
Caffeine consumption from coffee, tea, and other sources can produce an immediate, short-lived increase in blood pressure, and regular coffee drinking has been associated with a slight increases in blood pressure, but it is generally thought that habitual coffee or tea drinkers develop a tolerance to the hypertensive effects of caffeine.39–41 However, some studies showed that repeated administration of caffeine produced a persistent blood-pressure-increasing effect. For example, in 11 short-term trials looking at the effect of caffeine consumption (ranging from 14 to 79 days), average consumption was five cups of coffee per day, and this was associated with an increase of 2.4 mm Hg in systolic blood pressure and 1.2 mm Hg in diastolic blood pressure.42 Although the overall benefit of long-term avoidance of caffeine (from coffee, tea, chocolate, cola drinks, and some medications) on blood pressure is unclear, it appears that because some patients seem to respond quite favorably to caffeine avoidance, it should at least be attempted in patients with hypertension.
Nutritional Supplements
Magnesium
Potassium interacts in many body systems with magnesium, and low intracellular potassium levels may be the result of low magnesium intake. It is therefore appropriate to use supplemental magnesium (400 mg to 1,200 mg per day in divided dosages) along with potassium. This supplementation may also lower blood pressure.
A meta-analysis of 14 clinical trials that tested the effects of magnesium supplementation on high BP demonstrated clear dose-dependent blood pressure reductions—a drop of 4.3 mm Hg systolic and 2.3 mm Hg diastolic for each 10 mmol/day increase in magnesium dose.43
In one double-blind clinical study 21 male patients with high BP were given 600 mg per day of magnesium (as magnesium oxide) or a placebo.44 Mean blood pressure (the average between systolic and diastolic) decreased from 111 to 102 mm Hg. The patients who responded the best were those with reduced red blood cell potassium. After therapy with magnesium, the levels of intracellular sodium, potassium, and magnesium normalized, suggesting that one of the ways magnesium lowers blood pressure is through activation of the cellular membrane pump, which pumps sodium out of, and potassium into, the cell.
Considerable evidence indicates that in population studies a high intake of magnesium is associated with lower blood pressure. The principal source of magnesium in early studies was water. Water that is high in minerals such as magnesium is often referred to as “hard.” Numerous studies have demonstrated an inverse correlation between water hardness and high BP.45
These early studies gave way to more extensive dietary studies looking at the association of magnesium with high BP. These dietary studies found the same results as the studies of hard water. In one of the most extensive studies—the Honolulu Heart Study—systolic blood pressure was 6.4 mm Hg lower and diastolic blood pressure 3.1 mm Hg lower in the highest magnesium intake group compared with the lowest magnesium intake group.46
The studies of magnesium supplementation in the treatment of high BP have yielded mixed results. Although the overall results in a very detailed analysis of the data are quite favorable, the hypertensive patients who respond best appear to be those taking a diuretic, those with low RBC magnesium, or those with elevated intracellular sodium or decreased intracellular potassium.
The recommended intake for magnesium in cases of high BP appears to be approximately 6 to 10 mg/kg per day. Magnesium is available in several different forms. Although most are equally well absorbed, magnesium bound to organic compounds (aspartate, malate, succinate, fumarate, or citrate) is usually preferable to magnesium bound to mineral salts (oxide, gluconate, sulfate, or chloride).47,48 In addition, magnesium aspartate, malate, succinate, fumarate, or citrate may also help with fatigue, as the binding compounds are involved in the Krebs cycle, the final common pathway for the conversion of glucose, fatty acids, and amino acids to chemical energy. Minerals chelated to the Krebs cycle intermediates are better absorbed, used, and tolerated compared with inorganic mineral salts. In addition, although inorganic magnesium salts often cause diarrhea at higher dosages, organic forms of magnesium usually do not.
Like potassium, magnesium supplementation must be used with great care in patients with kidney disease.
Calcium
Population-based studies have suggested a link between high BP and a low intake of calcium. However, the association is not as strong as the one for magnesium and potassium. In addition to the epidemiological data, several clinical studies have demonstrated that calcium supplementation can lower blood pressure in cases of high BP, but the results have been inconsistent.49
To clarify the effectiveness of calcium supplementation for patients with high BP, one double-blind, placebo-controlled study was performed on 46 patients with either salt-sensitive or salt-resistant hypertension.50 During the calcium supplementation phase, patients received 1.5 g per day of calcium (as calcium carbonate) for eight weeks. The calcium supplementation was found to effectively reduce blood pressure in blacks and in patients who were salt-sensitive, but not in patients who had salt-resistant hypertension. Better results have been found for calcium citrate vs. calcium carbonate.51
Another group that appears to respond to calcium supplementation is the elderly with high BP. One study used monitoring of blood pressure to evaluate the effect of calcium supplementation on mild to moderate hypertension in elderly hospitalized patients. The mean systolic and diastolic blood pressures over a period of 24 hours declined by 13.6 mm Hg and 5 mm Hg, respectively, in patients whose diets were supplemented with 1 g elemental calcium.52
Vitamin C
Population-based and clinical studies have shown that the higher the intake of vitamin C, the lower the blood pressure. The results from several preliminary studies showing a modest blood-pressure-lowering effect with vitamin C supplementation in people with mild elevations of blood pressure have been confirmed in two recent double-blind trials.53,54 One of the key findings of these studies was that a daily dosage of 500 mg produced the same benefit as higher dosages (1,000 and 2,000 mg per day). Vitamin C supplementation can produce decreases of up to 4.5 mm Hg in systolic pressure and 2.5 mm Hg for diastolic pressure.
One of the ways vitamin C exerts this antihypertensive effect is by promoting the excretion of lead. Chronic exposure to lead from environmental sources including drinking water is associated with hypertension and increased cardiovascular mortality. Areas with a soft water supply often have an increased lead concentration in drinking water due to the greater acidity of the water, and people living in these areas may be predisposed to hypertension. It should be noted that soft water is also low in calcium and magnesium, two minerals that have been shown to protect against hypertension.
Vitamin C is likely to be more effective when used with other antioxidant nutrients. The combination of 500 mg vitamin C, 600 mg alpha-tocopherol, 200 mg zinc sulfate, and 30 mg beta-carotene per day produced mild reductions in systolic blood pressure compared with a placebo both in subjects receiving antihypertensive therapy and in those who had normal blood pressure.55
Folic Acid and Vitamin B6
Folic acid and vitamin B6 reduce levels of plasma homocysteine, a known contributor to atherosclerosis. A two-year trial of folic acid and B6 therapy to lower homocysteine was associated with a 3.7-mm-Hg lower systolic and a 1.9-mm-Hg lower diastolic blood pressure.56 Vitamin B6 supplementation alone has also been shown to lower blood pressure. In one study, vitamin B6 supplementation at a single oral daily dosage of 5 mg/kg for four weeks in 20 people with hypertension demonstrated significant reductions in blood pressure (systolic pressure dropped from 167 to 153 mm Hg, and diastolic pressure dropped from 108 to 98 mm Hg) as well as in serum norepinephrine levels.57
Omega-3 Fatty Acids
Increasing the intake of omega-3 fatty acids can lower blood pressure. More than 60 double-blind studies have demonstrated that fish oil supplements are effective in lowering blood pressure.58,59 However, the effect is modest. Typically, fish oils produced a reduction of 2.1 mm Hg for systolic blood pressure and 1.6 mm Hg for diastolic blood pressure at a typical dosage of 3,000 mg EPA + DHA per day. Flaxseed oil may also lower BP. The key to getting results with flaxseed oil may require reducing the intake of saturated fat and omega-6 fatty acids. In one study 1 tbsp per day of flaxseed oil along with a reduction in the intake of saturated fat resulted in a drop of up to 9 mm Hg in both the systolic and the diastolic readings.60 Another study found that for every absolute 1% increase in body alpha-linolenic acid content, there was a decrease of 5 mm Hg in the systolic, diastolic, and mean blood pressures.61
Arginine
Arginine is important for the formation of nitric oxide, a compound that plays a central role in relaxing blood vessels, thereby improving blood flow, and in improving kidney function. Normally, the body makes enough arginine, even when it is lacking in the diet. However, in some instances the body may not be able to keep up with increased requirements, and supplementation may prove useful. In high BP, even in mild cases, there appears to be a problem with nitric oxide production, especially in the kidneys.
Arginine supplementation has been shown to be beneficial in a number of cardiovascular diseases, including hypertension. By increasing nitric oxide levels, arginine supplementation improves blood flow, reduces blood clot formation, and improves blood fluidity. In hypertension, the degree of improvement offered by arginine supplementation can be quite significant in some cases,62,63 but in general a dosage of 4 g three times per day will produce only modest decreases (e.g., 5 mm Hg) in systolic BP with little meaningful change in diastolic BP.64 Arginine supplementation may prove to be most beneficial in younger subjects with high BP, as older subjects appear to have less effective nitric-oxide-dependent mechanisms. In a study of younger and older subjects with high BP, intravenous arginine induced a significant increase in kidney blood flow, filtration rate, and sodium excretion in the younger subjects.65 These effects were not observed in older subjects.
Anti-ACE Peptides
Various naturally occurring peptides have been shown to inhibit angiotensin-converting enzyme (ACE), which plays in role in processes that constrict large blood vessels and cause the kidneys to hold on to more sodium. The most thoroughly studied of these peptides is derived from a fish called bonito (a member of the tuna family).66–69 Anti-ACE bonito peptides do not appear to produce the side effects typical of ACE inhibitor drugs, according to human safety studies, and do not lower blood pressure in people with normal blood pressure—even when administered at levels 20 times greater than the dosage that reduces blood pressure in people with high BP. A possible reason is that their mechanism of action in inhibiting ACE is different from that of the drugs. Research bears out this theory. ACE converts angiotensin I to angiotensin II by cleaving off a small peptide. Drugs work by directly blocking this action. By contrast, naturally occurring anti-ACE peptides react with the peptides instead of with angiotensin.
Four clinical studies (three with the bonito peptides and one with a dipeptide from sardine) have shown that fish-derived anti-ACE peptides exert significant blood-pressure-lowering effects in people with high BP.67–70 Systolic blood pressure was typically reduced by at least 10 mm Hg and diastolic by 7 mm Hg in people with borderline and mild hypertension. Greater reductions are seen in people with higher initial blood pressure readings.
Coenzyme Q10 (CoQ10)
Coenzyme Q10, also known as ubiquinone, is an essential component of the mitochondria. Although CoQ10 can be synthesized within the body, deficiency states have been reported, especially in those taking statin drugs. CoQ10deficiency has been shown to be present in 39% of patients with hypertension. This finding alone suggests a need for CoQ10 supplementation. However, CoQ10 appears to provide benefits beyond correction of a deficiency.
The majority of studies exploring CoQ10 in the treatment of high BP have been uncontrolled, or have used CoQ10 in combination with conventional antihypertensive medical treatments, so these studies are difficult to interpret. A Cochrane review of CoQ10 in the treatment of hypertension (12 clinical trials, 362 patients) concluded that in hypertensive patients, CoQ10 has the potential to lower systolic and diastolic blood pressure without significant side effects.71 Among all included studies, decreases in systolic blood pressure ranged from 11 to 17 mm Hg and decreases in diastolic blood pressure from 8 to 10 mm Hg. In 3 of the 12 studies CoQ10 was given in addition to existing antihypertensive medication, and in one of these more than 50% of the patients were able to cease taking at least one antihypertensive medication during the trial. These results are consistent with some of the uncontrolled studies. For example, in one uncontrolled study, the dosage of CoQ10 was adjusted in 109 patients with high BP according to clinical response and blood CoQ10 levels (the aim was to attain blood levels over 2 mcg/ml). The average CoQ10 dose was 225 mg per day in addition to the patients’ usual antihypertensive regimen. The need for antihypertensive medication declined gradually, and after a mean treatment period of 4.4 months, about half of the patients were able to discontinue between one and three drugs.72
It is important to keep in mind that the antihypertensive effect of CoQ10 is usually not seen until after 4 to 12 weeks of therapy. Thus CoQ10 is not a typical blood-pressure-lowering drug; rather, it seems to correct some metabolic abnormality, which in turn has a favorable influence on blood pressure.73
Botanical Medicines
Hawthorn
Extracts of hawthorn (Crataegus species) berries, as well as of the flowering tops, are widely used by naturopathic physicians in Europe because of their cardiovascular activity. Several studies including double-blind trials have demonstrated that hawthorn extracts are effective in lowering blood pressure and improving heart function.74,75 However, the blood-pressure-lowering effect of hawthorn is mild, and the extracts usually need to be taken for at least two to four weeks before any effects are seen.
Olive
The leaves of the olive tree (Olea europaea) have been used since ancient times to combat high BP, and recent animal and human studies support their use as an antihypertensive as well as for lowering cholesterol. The active substances are oleuropein (a polyphenolic iridoid glycoside),76 oleacein, and oleanolic acid, which act as natural calcium-channel-blocking agents to relax constricted large blood vessels. Hydroxytyrusol is a metabolite of oleuropein that exerts antioxidant effects. Often olive extracts are standardized for hydroxytyrusol, but this compound has no significant effect on BP. Oleuropein is also found in the fruit and oil, but in significantly smaller quantities than in the leaf.
In an initial small, double-blind study of patients with essential hypertension—12 who had never been treated and 18 who were currently on antihypertensive drugs—olive leaf extract at a dosage of 400 mg four times per day for three months produced a modest yet statistically significant decrease of blood pressure with no side effects.77
QUICK REVIEW
• Elevated blood pressure is a major risk factor for heart attack and stroke.
• Most cases of borderline to mild hypertension can be treated with nondrug therapies.
• Vegetarians generally have lower blood pressure levels and a lower incidence of and other cardiovascular diseases than non-vegetarians.
• A high ratio of potassium to sodium in the diet is associated with lower blood pressure.
• Relaxation techniques have been shown to have some value in lowering blood pressure.
• Population-based and clinical studies have shown that the higher the intake of vitamin C, the lower the blood pressure.
• Chronic exposure to lead from environmental sources, including drinking water, is associated with high blood pressure and increased cardiovascular mortality.
• CoQ10 deficiency has been shown to be present in 39% of patients with high blood pressure, and supplementation with CoQ10 can lower blood pressure.
• More than 60 double-blind studies have demonstrated that either fish oil supplements or flaxseed oil exert some blood-pressure-lowering effect.
• Hawthorn, olive leaf, and hibiscus extracts have shown mild blood-pressure-lowering effects in double-blind studies.
More recent studies have utilized an extract standardized for oleuropein (16 to 24%) and polyphenols. In a preliminary clinical study carried out with 10 sets of identical adult twins with mild hypertension, one of the twins received a dose of either 500 or 1,000 mg per day and the other twin took a matching placebo. After eight weeks, systolic blood pressure remained unchanged from baseline in the placebo group and the group taking 500 mg per day but had significantly decreased for the group taking 1,000 mg per day (137 vs. 126 mm Hg).78
In another study, 232 patients with high BP were given either olive leaf extract (500 mg twice per day) or the conventional antihypertensive drug captopril (12.5 mg twice per day). The average reduction in blood pressure was 11.5 mm Hg systolic and 4.8 mm Hg diastolic in the olive group, compared with 13.7 mm Hg systolic and 6.4 mm Hg diastolic in the captopril group.79
Hibiscus
Hibiscus tea and extracts prepared from the dried flowers of Hibiscus sabdariffa have demonstrated antihypertensive properties in clinical trials. The active components are anthocyanidin glycosides. One double-blind trial was conducted with 65 prehypertensive and mildly hypertensive adults, 30 to 70 years of age, who were not taking antihypertensive medications. They were given either three 240-ml servings per day of brewed hibiscus tea or a placebo beverage. After six weeks, hibiscus tea had lowered systolic BP compared with the placebo (7.2 vs. 1.3 mm Hg). Diastolic BP was also lower, although this change did not differ from that with the placebo. Participants with higher systolic BP at baseline showed a greater response to hibiscus treatment.80
In another double-blind study, the effect of hibiscus tea was compared with black tea in 60 diabetic patients who had mild hypertension but were not taking antihypertensive or lipid-lowering drugs. Average systolic BP in the hibiscus group decreased from 134.4 mm Hg at the beginning of the study to 112.7 mm Hg after one month, while it increased from 118.6 to 127.3 mm Hg in the black tea group. The intervention had no statistically significant effect on diastolic BP in either group.81
Another study did show that hibiscus tea had an effect on diastolic BP (reduced by 10.7%) as well as systolic BP (reduced by 11.2%) after 12 days of treatment.82
Two clinical studies featured a standardized extract of hibiscus in high BP. In one double-blind study, 193 patients with hypertension were given either hibiscus extract (250 mg total anthocyanins per day) or 10 mg lisinopril (control group). Results showed that the hibiscus extract decreased systolic blood pressure by 17.14 mm Hg and diastolic by 11.97 mm Hg with no side effects, though the lisinopril was more effective. Hibiscus treatment lowered plasma ACE activity by 31 percent.83
Similar results with BP were shown in another double-blind study. A standardized hibiscus extract (9.6 mg total anthocyanins per day) was compared with another drug (captopril, 50 mg per day). Results showed no significant differences in lowering blood pressure between the two treatments. Hibiscus extract was able to decrease systolic BP from 139.05 to 123.73 mm Hg and diastolic BP from 90.81 to 79.52 mm Hg.84
TREATMENT SUMMARY
We recommend a comprehensive program that utilizes lifestyle, dietary, and supplemental strategies to lower blood pressure. Every effort should be made to achieve and maintain ideal body weight.
Borderline, Mild, or White-Coat Hypertension
• Achieve and maintain ideal body weight. See the chapter “Obesity and Weight Management” for more information.
• Substantially decrease salt intake.
• Follow a healthful lifestyle. Avoid alcohol, caffeine, and smoking. Exercise and use stress-reduction techniques.
• Follow a high-potassium diet rich in fiber and consistent with either the Mediterranean or the DASH Diet and the recommendations given in the chapter “A Health-Promoting Diet.”
• Increase dietary consumption of celery, garlic, and onions.
• Reduce or eliminate the intake of animal fats while increasing the intake of monounsaturated vegetable oils.
• Supplement with the following:
High-potency multivitamin and mineral formula
Vitamin C: 500 to 1,000 mg three times/day
Magnesium (preferably citrate): 6 to 10 mg/kg per day, in divided doses
Garlic: the equivalent of 4,000 mg per day of fresh garlic
Omega-3 fatty acids, either fish oils (3 g total EPA + DHA content per day) or flaxseed oil (1 tbsp per day)
If you have tried these recommendations for a period of three months but blood pressure has not returned to normal, follow the recommendations below for moderate hypertension.
Moderate Hypertension:
• All the measures mentioned under “Borderline, Mild, or White-Coat Hypertension”
• CoQ10: 200 to 300 mg per day
• Anti-ACE peptides from bonito: 1,500 mg per day
• One of the following:
Hawthorn extract (10% proanthocyanidins or 1.8% vitexin-4'-rhamnoside): 100 to 250 mg three times per day
Olive leaf extract (17% to 23% oleuropein content): 500 mg two times per day
Hibiscus: three cups of tea per day, or an extract providing 10 to 20 mg anthocyanidins per day
These guidelines should be followed for one to three months. If the blood pressure has not dropped below 140/105, medications to lower blood pressure may be required.
Severe Hypertension
Drug intervention is required. All the measures mentioned previously under “Borderline, Mild, or White-Coat Hypertension” and “Moderate Hypertension” should be employed as well. When satisfactory control over the high BP has been achieved, it may be possible to taper off the medication gradually under a physician’s supervision.