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Cholesterol 101
The doctor of the future will give no medicine, but will interest his patients in the care of the human frame, in diet, and in the cause and prevention of disease. —Thomas Alva Edison, American scientist and inventor (1847–1931)
CARDIOVASCULAR DISEASE:
WILL IT BE YOUR CAUSE OF DEATH?
Odds are that you will die from some form of cardiovascular disease—our nation’s deadliest epidemic—be it a heart attack, stroke, high blood pressure, or other disease of the heart and blood vessels. In the United States, one person dies from cardiovascular disease approximately every thirty-five seconds. Combine that overwhelming death toll with the staggering $403 billion estimated direct and indirect cost of cardiovascular disease for 2006, and you begin to grasp the magnitude of this huge public health concern.
More fearful that you will die of cancer? Recent American Heart Association statistics reveal that you are much more likely to succumb to a disease of the heart or blood vessels. In 2003, almost twice as many Americans died of cardiovascular disease as of cancer. In fact, cardiovascular disease claims more lives than the next four leading causes—cancer, respiratory diseases, accidents, and diabetes—combined.
If you are a woman and think your gender will protect you, you should know that in 2003 almost half a million American women died of cardiovascular disease, mainly heart disease. In fact, according to the American Heart Association’s 2003 statistics, a woman’s odds of dying from heart disease far surpassed her chances of dying from breast cancer (1 in 30 women who died did so of breast cancer, while 1 in 2.6 died of cardiovascular disease). Furthermore, more women succumbed to cardiovascular disease than men—approximately 60,000 more women than men. The truth is that women are different from men, both in their symptoms of heart disease and in the propensity of women to exhibit a different but just as deadly type of heart disease, “coronary microvascular disease” or a hardening of the minute arteries that feed the heart (but are too tiny to show up on a typical angiogram). According to new findings, high cholesterol and high blood pressure are among the leading causes of this condition.
The good news is that lifestyle modifications will provide you with a powerful measure of protection against diseases of the heart and blood vessels, including microvascular disease. By following the easy ten-step Cholesterol Down Plan outlined in Part II of this book, you can lower your “bad” cholesterol and maybe even save your life.
According to the World Health Organization’s report Global Strategy on Diet, Physical Activity, and Health, various forms of cardiovascular disease resulted in an estimated 16.7 million deaths globally in 2003. Most of these deaths were from heart disease (7.2 million) and stroke (5.5 million), with the rest attributed to high blood pressure and other vascular illnesses.
WHAT CAUSES HEART ATTACK OR STROKE?
A heart attack or stroke is ultimately caused by a corroding of LDL particles that accumulate within the inner arterial wall, resulting in inflammation and eventual thickening of the arterial walls leading to the heart or brain, a process called atherosclerosis. This slow, progressive disease typically starts in childhood, when cholesterol, cellular debris, fat, calcium, and other compounds begin building up in the large arteries. Over time, a poor diet and sedentary lifestyle predispose our arteries to clogging up with this thick mass of gunk, called plaque, with often fatal consequences. Eventually the plaque ruptures and a blood clot forms; the flow of blood, oxygen, and nutrients is blocked, and a heart attack or stroke ensues.
Fortunately, there are a number of simple lifestyle changes that can protect your arteries from atherosclerosis. In later chapters, you will see how the Cholesterol Down Plan works to dramatically cut your cholesterol and reduce your chances of developing cardiovascular disease, including atherosclerosis.
WHAT IS CHOLESTEROL, ANYWAY?
Everyone talks about cholesterol, but few people actually understand what it is. In physical terms, it is a white fat-like substance with a consistency like candle wax that can be found nearly everywhere in the body: in the membranes of all cells, in the bile stored in the liver, in steroid hormones, and—most important for the purposes of this book—floating through the bloodstream in transport vehicles known as lipoproteins. Despite its bad rap, some cholesterol is vitally important for good health, as it is a major building block for many structures within our bodies—even our bones and teeth, as cholesterol is a precursor for vitamin D.
THE CHOLESTEROL TRANSIT SYSTEM
Oil doesn’t mix with water, so it shouldn’t be a surprise that oily cholesterol doesn’t mix with blood, which is basically salty water. The body solves this problem by producing waterproof cholesterol transporters called lipoproteins. In addition to cholesterol, lipoproteins also ferry around dietary fat (known in scientific circles as triglyceride, or triacylglycerol) and the fat-soluble vitamins E, D, A, and K. If you were to assemble a lipoprotein, you would need four building blocks: protein, cholesterol, triglycerides, and phospholipids (another type of waxy fat-like material found in high concentration in cell membranes). The amount of each substance varies depending on the class of lipoprotein.
THE FOUR TYPES OF LIPOPROTEINS
Lipoproteins are divided into four main classes according to density: chylomicrons, VLDL, LDL, and HDL (Figure 1.1). Lower-density lipoproteins are characterized by a higher fat-to-protein ratio (fat is lighter) and therefore float more easily in the blood. Here are the basics about the four classes of lipoproteins in order of increasing density:
• Chylomicrons are the least dense of all the lipoproteins and are basically just big balls of fat (triglycerides), with a makeup of about 90 percent fat, a touch of phospholipids, some cholesterol, and a smidgin of protein.
• VLDL (very low-density lipoprotein) carries a great amount of fat, some phospholipids, and cholesterol. The high fat content of VLDL makes a large quantity of this lipoprotein in the blood undesirable.
• LDL (low-density lipoprotein, or “bad” cholesterol) has only a fraction of the fat and double the protein of VLDL and is very high in cholesterol. This lipoprotein carries the majority of cholesterol in the blood and is considered the unhealthy one.
• HDL (high-density lipoprotein, or “good” cholesterol) is a spherical blob of mostly protein (albeit a type different from that found in LDL), some cholesterol, phospholipids, and very little fat. The densest of all the lipoproteins, HDL is the healthy one.
MEASURING YOUR CHOLESTEROL
Your doctor will ask you to fast overnight before having your blood drawn to measure your lipoprotein levels. Fasting ensures that the chylomicrons are gone and have no effect on the sum total of cholesterol or triglycerides swimming around your bloodstream. The lab report will analyze your blood specimen for HDL, LDL, and VLDL. It will show the amount of “good” cholesterol (HDL), “bad” cholesterol (LDL), and triglycerides (blood fat) in the bloodstream. Your doctor may also test you for some risky particle characteristics— such as small and dense LDLs, small HDLs, or big VLDL particles—if you are at high risk for heart disease.
The key to a healthy blood test lies in the cholesterol transport: where the cholesterol goes, how it gets there, and how much of it accumulates. The blood test measures the quantity of cholesterol transport vehicles (aka lipoproteins). A healthy blood test shows a high number of HDL cholesterol transporters (the lipoprotein that carries cholesterol out of the arteries back to the liver for degradation). Too much LDL is unhealthy because it can build up in the inner arterial wall that feeds the heart and brain. In combination with other substances, the cholesterol in LDL forms plaque, which clogs the arteries (atherosclerosis). If a blood clot forms, cells downstream die and a heart attack or stroke occurs. Atherosclerosis is therefore a disease related to problems with cholesterol transport.
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