Hospital corpsman Third Class (HM3) Ralph Sample takes the blood pressure reading of Staff Sergeant David Dearing (USA Washington State National Guard) at the Branch Medical Clinic.

Your engine is geared-up for the increased demand of your daily routine: not just a normal trip to the store, but an uphill climb with curves and icy roads. Suddenly a light flashes on, a "check engine" warning. Unfortunately, it's your body, not your automobile. You can't lift the hood to search for the problem. Should you drive forward, ignoring the signal, hoping it will soon go off, or do you stop to examine the problem closer? Your blood cholesterol level, blood pressure, and blood glucose levels are your body's signals that go on and off in relationship to your health, and at times you wonder what a flashing warning light means for your body. Will you wreck the engine if you ignore the warnings?

The Connection Between Elevated Cholesterol and Your Health

Americans are conscious of cholesterol like never before, but not necessarily aware of its relationship to health. It is a medical fact high blood cholesterol increases a person's risk of coronary artery disease (CAD) and heart attack. But, unlike a "check engine light", a cholesterol measure is like a temperature gauge - what's too high? When are you running too hot? What do those numbers mean, anyway?

Cholesterol is a white, waxy, fat-like substance. You cannot taste it or see it in the foods you eat. Although we usually think of it as being found in the bloodstream, it is present everywhere in the body. Cholesterol is essential for life: it is found in the outer membranes of our cells, in the fatty insulation around nerves, and as a chemical building block of some hormones. Despite its importance, cholesterol isn't an essential nutrient, because most of the cholesterol in your body is manufactured from the food you eat. Even if you didn't eat any cholesterol, your liver would make enough for your body's needs. The body produces about 1000 milligrams of cholesterol a day. In addition, the typical American consumes another 400 milligrams of cholesterol a day from foods such as meats, eggs and dairy products (exclusively animal products). In fact, there are two "types" of cholesterol in your body. The first type comes from dietary sources, and the second type is manufactured in the liver. Both types are chemically the same and end up in your bloodstream.

Cholesterol is like a fat, in that it will not mix with water. To carry it in the blood, the liver puts together packages called lipoproteins, consisting of proteins, cholesterol, and fats called triglycerides from your diet. The largest of these lipoprotein packages is very-low-density lipoprotein, or VLDL. As it circulates in the bloodstream, the VLDL drops off the triglycerides to the cells to be used for energy or stored as fat. When VLDL drops off its trigylcerides, the remainder of the package is smaller, and contains only the cholesterol wrapped in protein. It is then called low-density lipoprotein, or LDL. Like a messenger, LDL carries cholesterol throughout the body, dropping it off in cells to perform its essential jobs through metabolism. Unused LDL that is not broken down by the liver remains circulating in the bloodstream, where it tends to accumulate in blood vessels. That's where it causes trouble for us. One of the main consequences of excessive cholesterol in our body is a disorder known as atherosclerosis.

Atherosclerosis (hardening of the arteries) contributes to nearly one-half of deaths and illness in the United States. All the arteries throughout the body, down to the size of a small straw, are the site of this problem. Small nodules called plaque, mostly of cholesterol, accumulate on the inside walls of these arteries at sites where wear and tear is greatest. This accumulation narrows the blood vessels and can restrict oxygen-carrying blood. The problem is, you can't feel atherosclerosis until the blockages impede the blood flow so much that tissues (like your heart muscle) become starved for oxygen and release pain-causing chemicals to signal that fact. It may take decades to reach this point, but only minutes to go beyond it to chest pain, heart attack, or sudden death.

Fortunately, the liver also makes another package called high-density-lipoprotein, or HDL. It too is composed of proteins, fats and cholesterol, but HDL carries less cholesterol than LDL. As it circulates through the bloodstream, HDL has the beneficial capacity to pick up excess cholesterol and carry it back to the liver for reuse or destruction. In simple terms then, LDL brings cholesterol to your arteries and can cause heart disease. HDL carries cholesterol away for reprocessing or removal by the liver. Researchers have noted that persons with higher levels of HDL have less heart disease. Thus, HDLs have been known as the "good" cholesterol. Women generally have higher levels of HDL because estrogen tends to raise HDL levels, and this may explain in part why they have a lower rate of heart attacks during childbearing years.

Your Cholesterol Level: Normal Versus Safe

When your cholesterol is checked, the physician or nurse looks at two values: the concentrations of total cholesterol, and HDL cholesterol in your blood. The results for total cholesterol usually range between 150 - 300, the number of milligrams per deciliter of blood (a little less than half a cup). The average American has a total cholesterol level of 210 mg/dl. This is considered "normal" in the statistical sense of average, but it certainly isn't optimal. These "normal" levels contribute over one and one-half million heart attacks a year!

What's a good or unhealthy blood cholesterol level? The National Institutes of Health recommends that doctors classify cholesterol tests like this. If someone does not have known coronary heart disease, a total cholesterol result below 200 mg/dl is classified as "desirable blood cholesterol"; levels between 200 and 239 mg/dl as "borderline-high blood cholesterol"; and results that exceed 239 mg/dl as "high blood cholesterol". The 240 mg/dl cutpoint is a value from which the risk to heart disease rises more steeply, and corresponds to the 80th percentile of the US adult population. In other words, at a cholesterol result of 240 mg/dl and beyond, your warning light is glowing especially bright!

Airman 1st class Heidi Patrick, from the 363rd Air Transportable Hospital takes the blood pressure of a Patient during Operation Desert Shield.

From numerous studies, higher cholesterol levels are associated with increasing risk for heart disease. Evidence from 362,000 men screened in a major study, the Multiple Risk Factor Intervention Trials (MrFIT) indicates that those whose total serum cholesterol levels exceeded 250 mg/dl experienced death from coronary heart disease at a rate five times greater than those with blood cholesterol levels below 150 mg/dl. Experts now believe that to be at low risk for heart disease, people over 30 years-old should have a total cholesterol less than 200 mg/dl.

Average HDL levels are between 45 and 65 mg/dl, but doctors classify an HDL cholesterol below 35 mg/dl as "low", and the American Heart Association warns that it constitutes a risk for heart disease. Available evidence shows that for every1 mg/dl decrease in HDL, your risk for heart disease increases by 2 to 3 percent.

Doctors also compare the ratio of your total cholesterol to your "good" cholesterol. A long-term study around the Boston suburb of Framingham indicated that values of this ratio are associated with increasing risk of heart attacks, with values of 4 and above indicating more risk. There is great concern when a person's total cholesterol/HDL ratio is greater than 6 (for example, a person who has a total cholesterol value of 220 mg/dl and an HDL level of 36 mg/dl.). At least four studies found that people with total cholesterol values below 200 mg/dl were still at risk if their HDL values were low; and that some people with elevated cholesterol levels would not be at risk because their HDL levels were very high. The lower the ratio, the better. Low-risk vegetarians have an average ratio of 2.5. Marathon runners are slightly higher at 3.4. The average U.S. male victim of heart disease has a ratio between 5.5 and 6.1.

Your target ratio is below 4.0, and the warnings sound when the level is exceeded. For low levels of cholesterol, the first line of defense is physical activity, weight loss, and smoking cessation. However, it's important to know that no clinical study has ever shown that people with low HDL can reduce their risk of heart disease by simply raising their HDL level, so a comprehensive approach to managing your cholesterol is required to prevent heart disease.

Your blood cholesterol level is mainly determined by your particular body chemistry, which is an inherited trait like hair or eye color. However, about 25 percent of your blood cholesterol is the result of the food you eat. Your body's response to altering the amount of cholesterol and fat in your diet is partially determined by inheritance. Other evidence suggests that a diet that is high in saturated fats (from sources including beef, butter, whole-milk dairy products, dark meat poultry, poultry skin, and coconut and palm oils) is related to high cholesterol levels. The people of Finland, for example, have the world's highest consumption of saturated fat in their diets, the highest cholesterol levels, and the greatest rate of heart disease too. By contrast, the Japanese eat a diet that is very low in saturated fat, and have the world's lowest cholesterol levels and heart disease of any developed nation.

Although cholesterol over 200 is a warning light, it may mean more or less depending on your personal factors. These would include whether either of your parents suffered a heart attack before age 60, whether you smoke, your blood pressure and blood sugar levels, your exercise patterns, and the way in which you handle stress. The risk factors for heart disease are synergistic, the more risk factors you have, the harder you must work to lower your risk.

If you are trying to lower your cholesterol level, you should use a strategy that includes the following:

1. Take steps to lose weight. Not only does this help lower your cholesterol (each pound of excessive weight contributes one mg/dl of cholesterol), but being overweight is another risk factor for heart disease. Your weight can be reduced by increasing the number of calories used (exercise) and by reducing the number of calories taken in (diet). One study found that weight loss increased HDL levels by 10 percent, with a 40 percent increase in the type of HDL that is especially protective.
2. Substitute unsaturated fats for saturated fats. In the typical American diet, the saturated fat context is the greatest contributor to raising blood cholesterol. Studies have shown that polyunsaturated fats (safflower, sesame and soybean oil are good sources) and monounsaturated fats (like olive oil) help to lower cholesterol levels. Monounsaturated fats may increase your HDL level as well. Polyunsaturates will lower blood cholesterol, but only half as much as saturated fats will raise it. In other words, if eating a given amount of saturated fat will raise your level by 10 percent, eating the same amount of polyunsaturated fat will lower your blood cholesterol by only 5 percent. You should substitute, not add, these fats to your diet - remember, fat is still fat!
3. Exercise. A study at Stanford University showed that regular exercise helps lower cholesterol and raise HDL. The Stanford studies also suggested (in a study of sedentary men) that 8-10 miles per week of running is required for significant HDL changes. Body fat loss correlated positively with distance run, with increase in HDL, and with increase in caloric intake.
4. Increase your consumption of foods high in soluble fiber. This is especially found in legumes and other vegetables, such as black-eyed peas, kidney beans, carrots, split peas, corn, and prunes. Other vegetables such as zucchini and broccoli have some soluble fiber, as do bananas, apples, pears and oranges. Therefore, if you regularly have a high fiber, low-fat diet you will probably see a change in your cholesterol levels on your next check.
5. Make some practical changes in your eating habits. Choose fish and poultry over cuts of red meat; remove skin from chicken before eating; use skim or low fat milk and choose low fat cheeses; eat fewer egg yolks; eat less commercial baked goods made from lard, coconut oil, palm oil or shortening; eat less fried foods. You should already know your cholesterol numbers, and have them rechecked at least every 5 years. If they exceed the acceptable ranges, you should have them checked more frequently based on the recommendations of your health care provider. It is important to know your blood cholesterol values, but it is more important to appreciate how they fit into the total risk picture for heart disease. Whether the warning lights are dim or radiant, it's essential to heed alarms that signal long-term problems to your living engine.

Watching Your Internal Pressure

Pressure is a stimulus, external or internal, to which we respond. When we speak of ordinary pressures, we mean the daily routines, responsibilities, and chores that keep us going, usually in some kind of work schedule or what might be called a "social harness." They are expectations guiding both work and recreation that define our "normal" path. When our work or leisure becomes unbalanced, we usually have trouble, in the form of stress.

In the same way, we keep an internal pressure in the circulatory system of the body. The force that keeps blood moving comes from the heart, but a complex system of nerves and hormones regulates this flow. Blood pressure is another one of those functions of our internal engine that needs a periodic check. Untreated blood pressure is the leading cause of strokes. As a result of hypertension, the heart works harder and may become enlarged and less efficient. Added blood pressure also damages artery walls and increases the deposits of fatty plaque and the risk of atherosclerosis. Hypertension is called the "silent killer" because it produces no symptoms that people can ordinarily recognize in themselves until significant damage has been done. Unfortunately, when the pressure rises, there is no monitoring light to warn an individual and the only way to see if it is elevated is to have it checked.

A blood pressure check is a simple procedure that uses a measuring device to find the point of greatest internal pressure (called systolic) that would lift a column of mercury to a certain height. This value corresponds to the force that the blood exerts against the vessel walls as the heart contracts and pushes blood out into the vascular system. For example, at its highest normal pressure the heart would send a column of mercury to about 120 millimeters. Then, a second measurement records the point of lowest pressure (called diastolic) as the heart rests and the pressure against the arteries subsides. A normal diastolic pressure would lift a column of mercury about 80 millimeters. These pressures would be recorded as systolic/diastolic values; for example, 120/80.

It is very common for the blood pressure to fluctuate. It changes second by second and day by day. For example your blood pressure will rise when you exercise or become agitated or excited, and will lower when you are at rest. Therefore, many of your blood pressure readings may be elevated the day you have a medical appointment because of fear of the unknown or apprehension about the physical exam, more commonly called the " white coat syndrome".

So, you sit down for your yearly physical and the technician checks your blood pressure and records it as 132/86. No one says anything to you whether that is a good reading or not, so you ask, "How is it?" The answer could be cryptic, from "It's borderline high," to "It's elevated." You are now more confused about the warning light; what does it mean?

As was mentioned above, your blood pressure does fluctuate, so the medical diagnosis requires more than just one elevated reading. An individual would never be diagnosed as hypertensive on the basis of one blood pressure reading alone. You may be asked to have it re-checked one or more times over a few days in order to compare the results and find an average value. (For accuracy, however, it is important that you rest for at least ten minutes before it is measured each time.) Recent research has shown that serial blood pressures measured at home are a better predictor of hypertension that those taken in a doctor's office.

Blood pressure, above 140/90, but less than 160/100, according to most experts, is called Stage 1 hypertension. About 70 percent of people with high blood pressure have relatively "mild" hypertension - systolic pressure between 140 and 159, diastolic pressure between 90 and 99. Many cases of hypertension worsen over time if untreated. Moreover, slightly elevated blood pressure (120 to 139 systolic or 85 to 89 diastolic), called "pre-hypertension," can still be dangerous if it persists. It is important to note that hypertension or pre-hypertension can exist if only one of the two numbers is elevated.

How does normal blood pressure turn into that condition called hypertension that affects at least 50 million people in the U.S.? The small blood vessels called arterioles, which widen and constrict, are the main regulators of blood pressure. When the regulatory system goes awry, the arterioles stay constricted, and the blood pressure stays chronically high. The cause of this condition in most cases is unknown and is termed "essential hypertension."

The table below, helps to categorize the medical options that are associated with a diagnosis of high blood pressure:

Blood Pressure Classification*	Blood Pressure level (mm Hg)
Normal	Systolic BP <120 AND Diastolic BP <80
Pre-Hypertension	Systolic BP= 120–139 OR Diastolic BP= 80-89
Stage 1 Hypertension	Systolic BP= 140–159 OR Diastolic BP= 90-99
Stage 2 Hypertension	Systolic BP= 160 or higher OR Diastolic BP= 100 or higher

* If the systolic and diastolic blood pressure measurements fall into two different categories, the blood pressure classification is the higher of the two categories.
Source: The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.

How Can I Prevent Hypertension? What Life-Style Changes Will Control It If I Have It?

Controlling your high blood pressure reduces your chances of suffering from the complications of hypertension - stroke, heart disease and kidney disease. Certain hereditary factors contribute to your risk of hypertension, but there are factors you can successfully control.

The National High Blood Pressure Education Program Working Group Report on Primary Prevention of Hypertension (1993) suggests that weight loss, a reduction in sodium (salt) intake, avoidance of excessive alcohol, and increased physical activity are the efficacious approaches to the primary prevention of hypertension. These guidelines should be an important part of everyone's daily regimen. However, what if your blood pressure is already high or you have essential hypertension. What then are the treatment options? If you weigh more than your ideal body weight, you are advised to lose weight. Losing only a few pounds can reduce blood pressure. The Trials of Hypertension Prevention Collaborative Research Group reported in the Journal of the American Medical Association in March of 1992, that weight reduction is the most effective of the strategies tested for reducing blood pressure. This same research also found that reduction in the salt or sodium in the diet is effective in lowering blood pressure. There seems to be a big debate out there as to the role that salt plays in elevating blood pressure. In review of the literature, there is no question that decreasing salt intake lowers the blood pressure in an individual with high blood pressure. The question remains, however, will an increased salt intake raise the blood pressure in an individual that does not have hypertension? The answer appears to boil down to whether the individuals system is sensitive to salt intake or not (about 10 to 15 % of the population is salt-sensitive). The guideline from the American Heart Association recommend no more than 2,400 milligrams of salt (the equivalent of one teaspoon) daily. Smoking and caffeine containing beverages definitely have an impact on raising the blood pressure. They don't cause hypertension, but smoking does promote the acceleration of coronary artery disease and both worsen the blood pressure control in someone who is hypertensive. Stressors in your environment do not directly cause hypertension, but your stress response can keep your blood pressure elevated at hazardous levels. Relaxation, meditation, and/or behavioral modification techniques may also be an area you need to explore further and learn to incorporate into your lifestyle.

Blood Pressure and Exercise

Exercise has been shown to reduce average blood pressure slightly; the average reduction in both systolic and diastolic values is approximately 6 to 10 points. This reduction in many studies has been shown to be independent of weight loss. Not a huge amount, but enough in many cases to postpone the need for medications or allow someone to decrease the amount of medications that they are currently taking. Many people with high blood pressure have traditionally been warned to avoid isometric exercise, such as weight training or pushing against a wall, since studies have shown that it can cause a dramatic rise in blood pressure. Research shows mixed results on this issue, with the most favorable outcomes in the range of a 10 point reduction in blood pressure values. While moderate isometric exercise raises blood pressure temporarily during exertion, researchers speculate that over time it may stimulate a "rebound effect," causing the body to adjust blood vessel resistance. Overall, research suggests that if you have high blood pressure and do isometric exercise, keep the intensity light to moderate, rest between brief bouts, and never hold your breath while exerting a force. Though exercise is a useful adjunct in the treatment of hypertension, particularly because of its association with decreasing body weight, it is seldom enough by itself.

If you are following all of the above recommendations, and your blood pressure still remains elevated, it is far better to take a blood pressure reducing medication than to ignore you have elevated blood pressure. There are many safe medications prescribed to control high blood pressure with a low side effect profile. One clinical investigator, Dr. James Neaton, found that drug treatment in combination with lifestyle modification was more effective in preventing cardiovascular and other clinical events than was just the lifestyle modification alone. There is a time when medications may be necessary to help control your blood pressure. Don't allow that signal light to stay on continuously and ignore your elevated blood pressure until irreversible damage has occurred to your engine. Instead have it monitored frequently and follow the suggested guidelines.

Summary

Our body tells us when it's working right, and sends out warning signals to help us maintain our wellness. Unlike a mechanical engine, the gauges and lights are a bit more obscure, but medicine has developed powerful ways to read them. If we pay attention to these signals, we will have the time for preventive maintenance that gives us the full mileage on our physical engines in all conditions.

See also:
Preventing High Blood Pressure
High Blood Pressure
Preventing Stroke

Source: carlisle-www.army.mil/apfri/book/results.htm

* Original article updated September 2004 to incorporate new research findings.