High Blood Pressure-A

High blood pressure (sometimes called hypertension) has been nicknamed the silent epidemic because of its far-reaching consequences. Today, nearly one of every three American adults (65 million people) has high blood pressure. In 2002, high blood pressure was implicated in almost 50,000 deaths. It is the 13th largest cause of death in the United States (American Heart Association 2005). Amazingly, studies based on the well-known Framingham Heart Study have estimated that a 55-year-old person who has normal blood pressure has a 90-percent lifetime risk of getting high blood pressure (Vasan RS et al 2002). High blood pressure has been associated with damage to blood vessels in the eyes, heart, brain, and kidneys (Wong ND et al 2005).

Sadly, however, millions of Americans who think their blood pressure is under control may be wrong. Numerous studies have shown that most people treated with antihypertensive drugs (drugs that lower blood pressure) still have higher-than-optimal blood pressure (American Heart Association 2005; Hyman DJ et al 2002). According to physicians at the Baylor College of Medicine, only 27 percent of Americans who have high blood pressure have their blood pressure effectively controlled to levels below 140 milligrams per deciliter (mg/dL) (Hyman DJ et al 2002). The problem is worse among elderly women. A study published in 2005 in the Journal of the American Medical Association found that the high blood pressure of 77 percent of women older than 80 years was not sufficiently controlled even if they were under a physician’s care (Lloyd-Jones DM et al 2005).

Perhaps most alarming of all, in many of these studies, the optimal blood pressure target was identified as less than 140/90 mg/dL, the cutoff level normally used to diagnose high blood pressure. However, studies have shown that a level of less than 120/80 mg/dL is even safer. This means that millions of Americans are candidates for blood pressure control even though they have not been identified as having high blood pressure (Chobanian AV et al 2003).


Because high blood pressure is a multifactorial problem, effective management is rarely achieved through one drug. Instead, optimal management often requires a broad-based approach that includes both pharmaceutical and nutritional components, along with regular self-monitoring of blood pressure. Compelling evidence indicates that many conditions that lead to and sustain high blood pressure can be corrected through an integrative approach emphasizing lifestyle modification, pharmaceutical agents, and nutritional support. These approaches will be discussed in detail throughout this chapter.

What Is High Blood Pressure?
Blood pressure is a measurement of the force exerted by blood as it flows through the arteries. High blood pressure occurs when there is an increase of force against the arterial wall, with potentially damaging consequences. Among adults, a normal blood pressure measure is considered to be below 120/80 mm Hg. Any blood pressure reading higher than this reflects elevated blood pressure.

The force of blood pressure is measured in two stages: when the heart is contracting (systolic pressure) and relaxing (diastolic pressure). Blood pressure is always expressed in pressure units of millimeters of mercury (mm Hg), and written as systolic over diastolic pressure. For example, a blood pressure reading of 120/80 mm Hg would mean a systolic pressure of 120 mm Hg and a diastolic pressure of 80 mm Hg.

Table 1 gives the four blood pressure classifications according to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure:

Table 1. General Blood Pressure Guidelines for Individuals With No Other Known Disease

Blood Pressure Classification:

Systolic (mm Hg)-Normal-Less than 120

Diastolic (mm Hg)-Normal-Less than 80

Prehypertension-Systolic (mm Hg)-120 – 139

Prehypertension-Diastolic (mm Hg)-80 – 89


Stage 1 hypertension-Systolic (mm Hg)-140 – 159

Stage 2 hypertension-Systolic (mm Hg)-More than 159

Stage 2 hypertension-Diastolic (mm Hg)-More than 99

Source: Chobanian AV et al 2003

Physicians classify hypertension as either essential or secondary. Essential hypertension, which accounts for about 80 percent of cases, has no known cause. Secondary hypertension is caused by another condition (Table 2):

Table 2. Causes of Secondary Hypertension
Renal:

Secretion of excess aldosterone (a steroid hormone secreted by the adrenal cortex that regulates salt and water balance)
Kidney disease
Atherosclerotic narrowing of the renal artery (the major artery supplying the kidney)
Endocrine:

Oral contraceptives
Hormonal changes or imbalances
Adrenocortical hyperfunction, such as Cushing’s disease and syndrome, primary hyperaldosteronism, hereditary or congenital syndromes
Acromegaly (a disease caused by the secretion of excessive amounts of growth hormone)
Neurogenic:

Psychogenic (of mental or emotional origin)
Damage to the central nervous system, such as damage to the spinal cord, increased intracranial pressure, or tumors
Miscellaneous:

Sleep apnea
Constriction or narrowing of the aorta
High concentrations of calcium in the bloodstream
Carcinoid tumors that secrete serotonin
Toxemia of pregnancy
Source: Kasper DL et al 2005.


High blood pressure is dangerous in part because it rarely causes symptoms at first but is a risk factor for many other conditions. According to data gathered as part of the Framingham Heart Study, people who have high blood pressure are at significantly increased risk of developing dangerous conditions related to high blood pressure. In this study, for every 10 mm Hg increase in systolic pressure, there was a doubling of the risk of having a heart attack or stroke or of having kidney failure (Kannel WB 2003; Klag MJ et al 2003; Wolf PA 2003).

Although it rarely happens, high blood pressure occasionally causes symptoms such as dizziness, vertigo, tinnitus, dimmed vision, fatigue, palpitations, impotence, and even fainting (Kasper DL et al 2005). Extremely elevated blood pressure can cause a headache upon awakening or, even more rarely, nosebleed, nausea, or vomiting (Swales JD 1994).

The Double Danger of High Blood Pressure and Endothelial Dysfunction
In recent years, researchers have made tremendous strides in understanding the connection between high blood pressure and various cardiovascular diseases. It turns out that elevated blood pressure damages arteries at a basic level—the endothelium.

Arteries are made up of three layers. The outer layer is mostly connective tissue that provides support to the inner two layers. The middle layer is smooth muscle that contracts and expands to facilitate circulation and maintain optimal blood pressure. The inner layer of arteries is known as the endothelium. This layer is composed of a thin layer of cells that protects the integrity of the artery, promotes blood clotting in case of injury, communicates with the smooth muscle layer, and helps prevent toxins such as low-density lipoprotein (LDL) from penetrating into the middle of the artery.

When the endothelial layer is damaged, it can result in a thickened arterial wall and the abnormal aggregation of white blood cells. The accumulation of lipids such as LDL and triglycerides in the area can also occur. Sensing an injury, the endothelium stimulates a healing response that ultimately leads to an atherosclerotic plaque. Endothelial dysfunction is linked with the development of atherosclerosis, a leading cause of cardiovascular events (Kannel WB 1995; Collins R et al 1990).

High blood pressure and endothelial dysfunction are closely associated. Elevated blood pressure has been shown to contribute significantly to endothelial dysfunction. Physicians routinely measure the effects of high blood pressure by looking at target organ damage. In other words, treatment decisions are based on how much damage is being caused to organs such as the kidneys, eyes, or heart by elevated blood pressure. In recent years, the endothelium has been added to the list of target organs that can be damaged by high blood pressure (Felmeden DC et al 2005; Hausberg M et al 2005). High blood pressure has been shown to cause functional alterations in the endothelium that, in turn, are associated with decreased arterial mobility and increasing stiffness in the arterial wall (Hausberg M et al 2005).

This stiffness can have serious consequences. Arteries are far from passive tubes through which blood flows. Healthy arteries actually contract with the heart to help maintain hemostasis and regulate blood pressure. When the arteries can no longer contract sufficiently because they are too stiff, additional stress is placed on the heart's main pumping chamber, the left ventricle. As a result, the left ventricle may be enlarged (left ventricular hypertrophy) (Palmieri V et al 2005). Left ventricular hypertrophy is often the first sign that damage from uncontrolled high blood pressure has started to occur (Kannel WB et al 2005). If left ventricular hypertrophy is not treated, it may evolve into congestive heart failure.

The connection between endothelial dysfunction and high blood pressure is strong enough that progressive researchers believe endothelial function should be routinely measured among people who have high blood pressure (Cohuet G et al 2006; Felmeden DC et al 2005; Hausberg M et al 2005). By the time symptoms develop, significant damage has already been done. If endothelial dysfunction is diagnosed early, however, treatment can mitigate the damage (Cohuet G et al 2006).

Conventional Treatment of High Blood Pressure
Standard treatment of high blood pressure includes lifestyle modifications such as losing weight and cutting down substantially on salt intake. It may also include using prescription medications. Physicians may prescribe two or more classes of antihypertensive drugs in an effort to adequately control blood pressure (Fahey T 2004).

There are six primary classes of antihypertensive drugs:

Thiazide diuretics.

Thiazide or thiazidelike diuretics act on the kidneys to help rid the body of salt and water through urination. With less fluid in the body, blood volume goes down, which results in a fall in blood pressure (Fahey T 2004). Adverse effects of thiazide diuretics include sexual dysfunction, glucose intolerance, gout, elevated potassium level, and low sodium level (hyponatremia).
Beta blockers. Studies show that beta blockers are uniquely effective for treating high blood pressure in individuals who have had a heart attack because they decrease both the risk and the severity of a second heart attack. However, these drugs may worsen blood glucose control, elevate triglyceride level, and lower high-density lipoprotein (HDL—sometimes called the “good” cholesterol).
Angiotensin-converting enzyme (ACE) inhibitors. Angiotensin is made when the kidneys receive a signal to raise blood pressure. ACE inhibitors prevent or reduce the production of angiotensin, which keeps vessels from narrowing and helps them relax. This relaxation lowers blood pressure and increases the supply of blood and oxygen to the heart.

Angiotensin II receptor blockers (ARBs).
ARBs work similarly to ACE inhibitors. However, instead of inhibiting the production of the angiotensin enzyme in the kidneys, they block the effects of angiotensin on cell receptor membranes. They are more effective than ACE inhibitors in treating some people who have high blood pressure. They are particularly useful for treating high blood pressure in individuals who cannot tolerate ACE inhibitors well. Adverse effects of ARBs can include headache, drowsiness, diarrhea, and a metallic or salty taste in the mouth.

Calcium channel blockers (CCBs).

CCBs affect the transport of calcium into the cells of the heart and blood vessels, causing blood vessels to relax. This relaxation increases the blood and oxygen supply to the heart, lowers blood pressure, and reduces the heart’s workload. Physicians often recommend CCBs to treat high blood pressure in women who have pregnancy-induced high blood pressure, elderly patients, patients who have a history of angina (restriction of blood flow in the coronary arteries), or patients of African or Caribbean descent. CCBs are not a good choice for patients who have had a heart attack or who have congestive heart failure. Adverse effects of CCBs include constipation, swelling of the lower part of the legs, flushing, or headache.

Alpha blockers.
Alpha blockers block alpha receptors in vascular smooth muscle, preventing the uptake of catecholamines, which are produced in response to stress. This blocking mechanism permits blood vessel dilation and allows blood to flow more freely. Alpha blockers are not advised for those who have a history of (or are at risk for) congestive heart failure. Alpha blockers tend to interfere with the hemodynamic adjustments the body has to make when a person goes from sitting or lying down to standing. People using alpha blockers may experience a drop in blood pressure (called orthostatic hypotension) when they go from sitting or lying down to standing. Other common adverse effects include stuffy nose and dizziness.

Lifestyle Management of High Blood Pressure
If you have high blood pressure, it is important to understand the standard medical treatment, so that you and your physician can make the best decisions for your health.

Men and women with prehypertension (120-139/80-89 mm Hg) should have a goal of lowering their blood pressure to 115/75 mm Hg, unless they have chronic kidney disease or diabetes, in which case the goal should be less than 130/80 mm Hg (Chobanian AV et al 2003). Prehypertension can be treated with lifestyle modifications, unless the individual has chronic kidney disease or diabetes, in which case antihypertensive drugs are often recommended (Chobanian AV et al 2003).

People with high blood pressure or those who are prehypertensive can lower their blood pressure by losing weight and increasing physical activity (especially by doing aerobic activity for at least 30 minutes every day). The following major dietary modifications can also be helpful:

Initiate the DASH (Dietary Approaches to Stop Hypertension) eating plan, which increases dietary potassium, fiber, and calcium intake through a diet rich in fruits, vegetables, low-fat dairy products, whole grains, and foods with reduced saturated fat and reduced total fat content (Chobanian AV et al 2003). The DASH plan is also rich in magnesium, a crucial mineral that may help promote optimal blood pressure levels (Geleijnse JM et al 2004).
Limit alcohol consumption to no more than two drinks a day for men and no more than one drink a day for women (Chobanian AV et al 2003).
Reduce salt intake to no more than 2.4 grams (g) of sodium or 6 g of sodium chloride each day.


Natural Weapons Against High Blood Pressure: A Trinity of Nutrients

Blood pressure is controlled by a complex interplay of factors such as diet, genetics, response to stress, medications, and other underlying health conditions. Enlightened health care practitioners and their patients are discovering that inadequately controlled blood pressure requires a multifactorial strategy. An optimal strategy employs a combination of nutritional and pharmaceutical options to offer a comprehensive approach for normalizing blood pressure. This makes more sense considering that a large number of Americans do not achieve adequate blood pressure control on blood pressure medication alone.

In recent years, researchers have discovered a trio of nutrients that work together to help lower blood pressure. The following nutrients contain antioxidants and compounds that help reduce oxidative damage and relax the arteries:

Casein peptide.
While searching for a natural agent to help optimize blood pressure, researchers hydrolyzed (or split) the milk protein known as casein and isolated the C12 peptide. Clinical studies now show that the C12 peptide is a natural ACE inhibitor that has specific blood pressure–lowering effects (Karaki H et al 1990).

A small study conducted in the United States demonstrated C12 peptide’s effectiveness in helping to normalize high blood pressure. This randomized, double-blind, placebo-controlled, crossover study examined 10 men and women (average age, 50 years) who had an average blood pressure of 152/98 mm Hg and were not taking antihypertensive medications. Each subject took a placebo for 6 days and then a single dose of either 200 mg or 400 mg C12 peptide. Blood pressure was monitored via a small blood pressure unit that each subject wore throughout the day. In the 200-mg and 400-mg treatment groups, systolic pressure declined significantly by an average of 2.4 mm Hg and 4.5 mm Hg, respectively, while diastolic pressure dropped by an average of 4.4 mm Hg and 6.5 mm Hg, respectively (Townsend RR et al 2004). The study results demonstrate that the C12 peptide has a notable impact on blood pressure after only a single dose.

A Japanese study sought to evaluate the longer-term benefits of supplementing with the C12 peptide. Eighteen mildly hypertensive subjects, with a mean blood pressure of 141/99 mm Hg, received 200 mg/day of the C12 peptide for 4 weeks. The researchers recorded significant reductions—4.6 mm Hg in systolic blood pressure and 6.6 mm Hg in diastolic blood pressure. Blood pressure declined gradually over the 4-week study period. A gradual decline is indicative of a healthy decline, as opposed to a dramatic drop that could cause dizziness or fainting. When treatment was halted, the subjects’ blood pressure began to return to the baseline levels that were recorded prior to treatment. The researchers also observed that the C12 peptide appears to have long-lasting effects. Even 2 weeks after treatment ended, diastolic blood pressure levels were still significantly lower than at baseline levels (Sekiya S et al 1992). No unfavorable side effects were reported.

The C12 peptide is not recommended for people who are allergic to dairy products and, like other ACE inhibitors, pregnant women should not take the C12 peptide.

Grape seed extract.
The C12 peptide is not the only natural agent that effectively supports healthy blood pressure levels. Grape seed extract, which is already known to have a wealth of health benefits, contains high concentrations of polyphenols, potent antioxidants that naturally increase the dilation (widening) of blood vessels. This dilation naturally increases blood flow while decreasing blood pressure (Siva B et al 2006).

A recent study sought to ascertain the effects of administering grape seed extract to prehypertensive subjects. For 4 weeks, 24 patients who had a mean blood pressure of 130/79 mm Hg were given placebo or 150 mg or 300 mg of a standardized, polyphenol-rich grape seed extract. Both doses of grape seed extract significantly reduced the subjects’ blood pressure compared to baseline levels. The researchers concluded that grape seed extract may be beneficial in lowering the blood pressure of people who are prehypertensive (Siva B et al 2006).

In addition to benefiting individuals who are prehypertensive, grape seed extract may help improve impaired endothelial function, an initiating factor in heart disease. In an important laboratory study, grape seed extract helped to inhibit the synthesis of a protein associated with endothelial dysfunction and mortality, while promoting the dilation of blood vessels (Corder R et al 2004). These findings led the researchers to propose that grape seed extract may be a critical nutrient for restoring impaired endothelial function, protecting against cardiovascular disease, America’s number-one killer.

Grape seed extract is considered safe and is well tolerated. A formal toxicity assessment that evaluated the impact of chronic high doses of grape seed extract in rats found no adverse treatment-related changes (Bentivegna SS et al 2002).

Pomegranate extract.
Pomegranates are fast becoming known as one of the healthiest foods we can eat, largely because of their beneficial effects on cardiovascular health (Aviram M et al 2001). While many people drink pomegranate juice, pomegranate extract may hold even greater benefits.

The benefit of supplementing with pomegranate extract (rather than drinking the juice or eating the fruit) is that the extract, unlike the juice, contains virtually no sugar or calories, and requires no refrigeration to maintain optimal quality. Interestingly, commercial pomegranate juice and whole fruit extracts contain beneficial phytonutrients that are not obtained from eating the pomegranate fruit itself (Gil MI et al 2000). In particular, punicalagins, the primary antioxidant found in pomegranates, are concentrated in the husk and in the juice of the whole fruit (Gil MI et al 2000).

While some pomegranate products are standardized to contain high levels of ellagic acid (an antioxidant and phytonutrient that has anticancer potential), focusing on ellagic acid alone is unlikely to provide optimal synergy among the phytonutrients found within pomegranates (Lansky EP 2006). Emerging research suggests that products standardized in punicalagins confer the greatest benefit by providing the highest levels of pomegranate antioxidants.

Scientists are now studying pomegranate extract to uncover the many advantages it may have for human health. Pomegranates contain an array of beneficial phytonutrients such as phenolic compounds and tannins, including punicalagins, which are unique to pomegranates. Several compounds in pomegranates are potent antioxidants and ACE inhibitors (Aviram M et al 2001). Researchers have determined that oxidative stress can disrupt the balance of vasoconstricting and vasodilating biochemicals in the endothelium, contributing to high blood pressure and endothelial dysfunction. By quenching oxidative stress, antioxidants may help prevent vasoconstriction, lower blood pressure, and promote healthy endothelial function (Kitiyakara C et al 1998). Scientists believe that pomegranates, a potent source of antioxidants, may promote healthy blood pressure levels by enhancing the activity and preventing the degradation of an important vasodilating agent. These benefits may also lead to improvements in endothelial function (Ignarro LJ et al 2006).