PROPERTIES OF CHOLESTEROL
Cholesterol is a fatty, waxy substance made by your liver and found in every living cell in your body. It is necessary for certain essential functions, such as the production of hormones. Many people who eat a diet rich in fatty foods have high cholesterol. Elevated cholesterol levels in the blood are caused by many factors, including being overweight, certain inherited tendencies, smoking and lack of exercise.
Too much cholesterol in your blood can create deposits on the inside
of your arteries. Over time, these build-ups may clog the arteries and
restrict blood flow - forcing your heart to work harder to keep the blood
moving. And if the blood can't bring enough oxygen to the heart muscle,
chest pain - and even heart attacks - can result. Experts believe that
most people should have a total cholesterol level under 200 mg to reduce
these risks absolutely, but a level of
200-240 may not increase risk significantly. In people older than 70, there is no current data that proves that lowering cholesterol helps increase life span or decrease illness or death, but many doctors feel that it is wise to control cholesterol in older people just as in younger people.
By testing your blood, your doctor can measure several substances relating to cholesterol: total cholesterol, triglycerides (another type of blood fat), as well as LDL and HDL (low- and high-density lipoproteins). LDL is the "bad" cholesterol that sticks to artery walls; HDL is the "good" cholesterol that helps the body reduce LDL. In general, total cholesterol is considered high when 240 or more, borderline when 200-239, and desirable when 200 or less. HDL should be above 35, and LDL should be below 160. However, patients at high risk of heart disease should have an LDL level below 120. Triglycerides should be below 160.
To lower cholesterol, and decrease your risk of heart attacks, heart failure, angina, stroke and dementia:
A 1994 study called the Scandinavian Simvastatin Survival Study (also called 4S) found that lowering cholesterol can prevent heart attacks and reduce death in men and women who already have heart disease and high cholesterol. For over 5 years, more than 4,400 patients with heart disease and total cholesterol levels of 213 mg/dL to 310 mg/dL were given either a cholesterol-lowering drug or a placebo (a dummy pill that looks exactly like the medication). The drug they were given is known as a statin, and it reduced total cholesterol levels by 25 percent and LDL-cholesterol levels by 35 percent. The study found that in those receiving statin, deaths from heart disease were reduced by 42 percent, the chance of having a nonfatal heart attack was reduced by 37 percent, and the need for bypass surgery or angioplasty was reduced by 37 percent. A very important finding is that deaths from causes other than cardiovascular disease were not increased, and so the 42 percent reduction in heart disease deaths resulted in a 30 percent drop in overall deaths from all causes.
The 4S researchers say that the following benefits could be expected if doctors were to treat their heart disease patients for the same 5-year period and lower cholesterol to the same extent. For every 1,000 patients:
A study published in 1998, the Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) study, examined the effects of cholesterol lowering in people with CHD (those who had already experienced a heart attack or had been hospitalized for angina) and who had relatively average cholesterol levels. The LIPID study used a statin drug to lower cholesterol levels in the treatment group. All study participants were counseled about following a cholesterol-lowering diet. The LIPID results showed that a drop of 18 percent in total cholesterol and 25 percent in LDL-cholesterol produced a 24 percent decrease in deaths from CHD among the treatment group compared with the control group. Similarly, cholesterol-lowering in the treatment group reduced the overall death rate by 22 percent, heart attacks by 29 percent, the need for bypass surgery or angioplasty by 20 percent, and stroke by 19 percent. Cholesterol lowering in the LIPID study resulted in significant reductions in CHD-related deaths and events without increasing non-CHD deaths.
These studies along with many others support the need to lower cholesterol levels in heart disease patients. If you lower your cholesterol, you too can see benefits like those in 4S, CARE, and LIPID.
Cholesterol travels in the blood in packages called lipoproteins. Just
like oil and water, cholesterol, which is fatty, and blood, which is watery,
do not mix. In order to be able to travel in the bloodstream, the cholesterol
made in the liver is combined with protein, making a lipoprotein. This
lipoprotein then carries the cholesterol through the bloodstream.
There are specific kinds of lipoproteins that contain cholesterol in your blood, and each affects your heart disease risk in a different way.
High density lipoproteins (HDL): the "good" cholesterol. HDL carry cholesterol in the blood from other parts of the body back to the liver, which leads to its removal from the body. So HDL help keep cholesterol from building up in the walls of the arteries. If your level of HDL-cholesterol is below 35 mg/dL, you are at substantially higher risk for heart disease. The higher your HDL-cholesterol, the better. The average HDL-cholesterol for men is about 45 mg/dL, and for women it is about 55 mg/dL.
Triglycerides: a form of fat carried through the bloodstream. Most of your body's fat is in the form of triglycerides stored in fat tissue. Only a small portion of your triglycerides is found in the bloodstream. High blood triglyceride levels alone do not necessarily cause arteriosclerosis. But some lipoproteins that are rich in triglycerides also contain cholesterol, which causes arteriosclerosis in some people with high triglycerides and high triglycerides are often accompanied by other factors (such as low HDL or a tendency toward diabetes) that raise heart disease risk. So high triglycerides may be a sign of a lipoprotein problem that contributes to heart disease.
Your blood cholesterol level is affected not only by what you eat but also by how quickly your body makes LDL-cholesterol and disposes of it. In fact, your body makes all the cholesterol it needs, and it is not necessary to take in any additional cholesterol from the foods you eat.
Patients with heart disease typically have too much LDL-cholesterol in their blood. Many factors help determine whether your LDL-cholesterol level is high or low. The following factors are the most important:
What you eat. Two main nutrients in the foods you eat make your LDL-cholesterol level go up: saturated fat, a type of fat found mostly in foods that come from animals; and cholesterol, which comes only from animal products. Saturated fat raises your LDL-cholesterol level more than anything else in the diet. Eating too much saturated fat and cholesterol is the main reason for high levels of cholesterol and a high rate of heart attacks in the United States. Reducing the amount of saturated fat and cholesterol you eat is a very important step in reducing your blood cholesterol levels.
Weight. Excess weight tends to increase your LDL-cholesterol level. If you are overweight and have a high LDL-cholesterol level, losing weight may help you lower it. Weight loss also helps to lower triglycerides and raise HDL.
Physical activity/exercise. Regular physical activity may lower LDL-cholesterol and raise HDL-cholesterol levels.
Age and sex. Before menopause, women usually have total cholesterol levels that are lower than those of men the same age. As women and men get older, their blood cholesterol levels rise until about 60 to 65 years of age. In women, menopause often causes an increase in their LDL-cholesterol and a decrease in their HDL- cholesterol level, and after the age of 50, women often have higher total cholesterol levels than men of the same age.
Alcohol. Alcohol intake increases HDL-cholesterol but does not lower LDL-cholesterol. Doctors don't know for certain whether alcohol also reduces the risk of heart disease. Drinking too much alcohol can damage the liver and heart muscle, lead to high blood pressure, and raise triglycerides (see the summaries of the articles on lowering triglycerides (1)and liver detoxification (2)by 1,4-Dicaffeoylquinic Acid, an active ingredient of Cynara scolymus extract present in Cynarex® and Cynarein® dietary supplements). Because of the risks, alcoholic beverages should not be used as a way to prevent heart disease.
Stress. Stress over the long term has been shown in several studies to raise blood cholesterol levels. One way that stress may do this is by affecting your habits. For example, when some people are under stress, they console themselves by eating fatty foods. The saturated fat and cholesterol in these foods contribute to higher levels of blood cholesterol.
Cholesterol is a major ingredient of the plaque that builds up in the coronary arteries and causes heart disease, so it is important to understand how plaques develop. Excess cholesterol is deposited in the artery walls as it travels through the bloodstream. Then, special cells in the artery wall gobble up this excess cholesterol, creating a "bump" in the artery wall. This cholesterol-rich "bump" then is covered by a scar that produces a hard coat or shell over the cholesterol and cell mixture. It is this collection of cholesterol covered by a scar that is called plaque.
The plaque buildup narrows the space in the coronary arteries through which blood can flow, decreasing the supply of oxygen and nutrients to the heart. If not enough oxygen-carrying blood can pass through the narrowed arteries to reach the heart muscle, the heart may respond with a pain called angina. The pain usually happens with exercise when the heart needs more oxygen. It is typically felt in the chest or sometimes in other places like the left arm and shoulder. However, this same inadequate blood supply may cause no symptoms.
Plaques come in various sizes and shapes. Throughout the coronary arteries many small plaques build themselves into the walls of the arteries, blocking less than half of the artery opening. These small plaques are often invisible on many of the tests doctors use to identify coronary heart disease. It used to be thought that the most dangerous plaques and the ones most likely to cause total blockage of coronary arteries were the largest ones. The largest plaques are in fact the ones most likely to cause angina. However, small plaques that are full of cholesterol and covered by a scar are now thought to be very unstable and more likely to rupture or burst, releasing their cholesterol contents into the bloodstream. When this happens, it triggers blood clotting inside the artery. If the blood clot totally blocks the artery, it stops blood flow and a heart attack occurs. The muscle on the far side of the blood clot does not get enough oxygen and begins to die. The damage can be permanent.
Lowering your blood cholesterol level can slow, stop, or even reverse the buildup of plaque. Cholesterol lowering can reduce your risk of a heart attack by lowering the cholesterol content in unstable plaques to make them more stable and less prone to rupture. This is why lowering your LDL-cholesterol is such an important way to reduce your risk for having a heart attack. Even in people who have had one heart attack, the chances of having future attacks can be substantially reduced by cholesterol lowering.
Chances are that you're visiting this web site because you or someone you know has heart disease - and you want to find out more about treatment options. There are some important things for you to know. The good news is that by lowering your blood cholesterol, you can reduce your risk of having a heart attack or other complications of heart disease.
The four steps you can take to lower your blood cholesterol: