Source American Heart Association
Cholesterol is a soft, waxy substance found among the lipids (fats) in the bloodstream and in all your body's cells. It's an important part of a healthy body because it's used to form cell membranes, some hormones and is needed for other functions. But a high level of cholesterol in the blood — hypercholesterolemia — is a major risk factor for coronary heart disease, which leads to heart attack.
Cholesterol and other fats can't dissolve in the blood. They have to be transported to and from the cells by special carriers called lipoproteins. There are several kinds, but the ones to focus on are low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
Low-density lipoprotein is the major cholesterol carrier in the blood. If too much LDL cholesterol circulates in the blood, it can slowly build up in the walls of the arteries feeding the heart and brain. Together with other substances it can form plaque, a thick, hard deposit that can clog those arteries. This condition is known as atherosclerosis. A clot (thrombus) that forms near this plaque can block the blood flow to part of the heart muscle and cause a heart attack. If a clot blocks the blood flow to part of the brain, a stroke results. A high level of LDL cholesterol (160 mg/dL and above) reflects an increased risk of heart disease. If you have heart disease, your LDL cholesterol should be less than 100 mg/dL. That's why LDL cholesterol is called "bad" cholesterol. Lower levels of LDL cholesterol reflect a lower risk of heart disease.
About one-third to one-fourth of blood cholesterol is carried by HDL. Medical experts think HDL tends to carry cholesterol away from the arteries and back to the liver, where it's passed from the body. Some experts believe HDL removes excess cholesterol from plaques and thus slows their growth. HDL cholesterol is known as "good" cholesterol because a high HDL level seems to protect against heart attack. The opposite is also true: a low HDL level (less than 40 mg/dL) indicates a greater risk. A low HDL cholesterol level also may raise stroke risk.
Lp(a) is a genetic variation of plasma LDL. A high level of Lp(a) is an important risk factor for developing atherosclerosis prematurely. How an increased Lp(a) contributes to heart disease isn't clear. The lesions in artery walls contain substances that may interact with Lp(a), leading to the buildup of fatty deposits.
What about cholesterol and diet?
People get cholesterol in two ways. The body — mainly the liver — produces varying amounts, usually about 1,000 milligrams a day. Foods also can contain cholesterol. Foods from animals (especially egg yolks, meat, poultry, fish, seafood and whole-milk dairy products) contain it. Foods from plants (fruits, vegetables, grains, nuts and seeds) don't contain cholesterol.
Typically the body makes all the cholesterol it needs, so people don't need to consume it. Saturated fatty acids are the main culprit in raising blood cholesterol, which increases your risk of heart disease. Trans fats also raise blood cholesterol. But dietary cholesterol also plays a part. The average American man consumes about 337 milligrams of cholesterol a day; the average woman, 217 milligrams.
Some of the excess dietary cholesterol is removed from the body through the liver. Still, the American Heart Association recommends that you limit your average daily cholesterol intake to less than 300 milligrams. If you have heart disease, limit your daily intake to less than 200 milligrams. Still, everyone should remember that by keeping their dietary intake of saturated fats low, they can significantly lower their dietary cholesterol intake. Foods high in saturated fat generally contain substantial amounts of dietary cholesterol.
People with severe high blood cholesterol levels may need an even greater reduction. Since cholesterol is in all foods from animal sources, care must be taken to eat no more than six ounces of lean meat, fish and poultry per day and to use fat-free and low-fat dairy products. High-quality proteins from vegetable sources such as beans are good substitutes for animal sources of protein.
How does physical activity affect cholesterol?
Regular physical activity increases HDL cholesterol in some people. A higher HDL cholesterol is linked with a lower risk of heart disease. Physical activity can also help control weight, diabetes and high blood pressure. Aerobic physical activity raises your heart and breathing rates. Regular moderate to intense physical activity such as brisk walking, jogging and swimming also condition your heart and lungs.
Physical inactivity is a major risk factor for heart disease.
Even moderate-intensity activities, if done daily, help reduce your risk. Examples are walking for pleasure, gardening, yard work, housework, dancing and prescribed home exercise.
How does tobacco smoke affect cholesterol?
Tobacco smoke is one of the six major risk factors of heart disease that you can change or treat. Smoking lowers HDL cholesterol levels and increases the tendency for blood to clot.
How does alcohol affect cholesterol?
In some studies, moderate use of alcohol is linked with higher HDL cholesterol levels. However, because of other risks, the benefit isn't great enough to recommend drinking alcohol if you don't do so already.
If you drink, do so in moderation. People who consume moderate amounts of alcohol (an average of one to two drinks per day for men and one drink per day for women) have a lower risk of heart disease than nondrinkers. However, increased consumption of alcohol brings other health dangers, such as alcoholism, high blood pressure, obesity, stroke, cancer, suicide, etc. Given these and other risks, the American Heart Association cautions people against increasing their alcohol intake or starting to drink if they don't already do so. Consult your doctor for advice on consuming alcohol in moderation.
Source American Heart Association
According to recent estimates, one in four U.S. adults has high blood pressure, but because there are no symptoms, nearly one-third of these people don't know they have it. In fact, many people have high blood pressure for years without knowing it. Uncontrolled high blood pressure can lead to stroke, heart attack, heart failure or kidney failure. This is why high blood pressure is often called the "silent killer." The only way to tell if you have high blood pressure is to have your blood pressure checked.
What Causes High Blood Pressure?
In 90 to 95 percent of high blood pressure cases, the cause is unknown. In fact, you can have high blood pressure for years without knowing it. That's why it's the “silent killer” — it creeps up on you. When the cause is unknown, you have what's called essential or primary hypertension. Factors that may lead to high blood pressure in the remaining 5-10 percent of cases, which are known as secondary hypertension, include:
These problems can usually be corrected. For example, doctors can repair a narrowed artery that supplies blood to a kidney. Most of these problems can be ruled out by a careful history, a physical examination and a few tests. Special tests are sometimes needed, but you don't usually have to stay in the hospital.
How does high blood pressure develop?
Certain nerve impulses cause your arteries to dilate (become larger) or contract (become smaller). If these vessels are wide open, blood can flow through easily. If they're narrow, it's harder for the blood to flow through them, and the pressure inside them increases. Then high blood pressure may occur. When this happens, your heart becomes strained and blood vessels may become damaged. Changes in the vessels that supply blood to your kidneys and brain may cause these organs to be affected.
Your heart, brain and kidneys can handle increased pressure for a long time. That's why you can live for years without any symptoms or ill effects. But that doesn't mean it's not hurting you. High blood pressure is a major risk factor for stroke, heart attack, heart failure and kidney failure.
What does high blood pressure do to your body?
What about low blood pressure?
Blood pressure less than 120/80 mm Hg is generally considered ideal. Levels higher than this increase your risk for cardiovascular disease. If you have unusually low blood pressure, have it evaluated.
Why Should I Care?
High blood pressure can hurt your body in many ways. It adds to the workload of your heart and arteries. Because your heart works harder than normal for a long time, it tends to get bigger. A slightly bigger heart may work well, but if it's enlarged very much, it may have a hard time meeting your body's demands.
High blood pressure is the No. 1 modifiable risk factor for stroke. It also contributes to heart attacks, heart failure, kidney failure and atherosclerosis (fatty buildups in arteries). In some cases, it can cause blindness. Recent studies show that in adults 40–89, the risk of death from heart disease and stroke begins to rise at blood pressures as low as 115/75. The risk doubles for each increased increment of 20 mmHg in systolic blood pressure or 10 mm Hg in diastolic blood pressure. Elevated systolic blood pressure indicates a more important risk than diastolic blood pressure except in patients younger than 50. The relationship of blood pressure levels to the risk of cardiovascular disease is continuous, consistent and independent of other risk factors. The higher the blood pressure, the greater is the chance for heart attack, heart failure, stroke and kidney disease.
Arteries and arterioles (small arteries) also suffer the effects of higher blood pressure. As you grow older, your arteries will harden and become less elastic. This occurs gradually in all people, even if they don't have high blood pressure. But having high blood pressure tends to speed up this process.
Arterial damage is bad because hardened or narrowed arteries may not be able to supply the amount of blood the body’s organs need. And if the body's organs don't get enough blood (and the oxygen and nutrients it delivers), they can't work properly. Another risk is that a blood clot may lodge in an artery narrowed by fatty deposits, depriving part of the body of its normal blood supply.
If you have high blood pressure, follow your doctor's advice. Most high blood pressure can't be cured, but it usually can be controlled. And its effects can be prevented or reduced — if it's treated and controlled early, and kept under control.