What is Cholesterol?

Cholesterol is a waxy, fat-like compound that belongs to a class of molecules called steroids. It’s found in many foods, in your bloodstream and in all your body’s cells. If you had a handful of cholesterol, it might feel like a soft, melted candle. Cholesterol is essential for:

  • Formation and maintenance of cell membranes (helps the cell to resist changes in temperature and protects and insulates nerve fibers)
  • Formation of sex hormones (progesterone, testosterone, estradiol, cortisol)
  • Production of bile salts, which help to digest food
  • Conversion into vitamin D in the skin when exposed to sunlight.

Cholesterol is a blood fat needed by the body in moderate amounts. However, high cholesterol levels can lead to atherosclerosis and coronary artery disease (CAD). Angina is chest pain caused by the restriction of blood flow to the heart (cardiac ischemia). Nitrates may be used to relieve angina.

Most people will have cholesterol blood tests regularly, including triglycerides, HDL, LDL and total cholesterol. Methods for increasing good cholesterol or lowering cholesterol levels may include cholesterol reducing drugs, such as statins, fibrates, niacin (nicotinic acid) and bile acid resins. However, these drugs do not reverse calcification. A heart attack occurs when the coronary arteries become blocked.

Cholesterol and blood do not mix well. So, for cholesterol to travel through your blood, it is coated with a layer of protein to make lipoprotein Two lipoproteins you may have heard about are high density lipoprotein, or HDL cholesterol, and low density lipoprotein , or LDL cholesterol.

Why is LDL cholesterol considered “bad”?

A high level of low-density lipoprotein, or LDL cholesterol, reflects an increased risk of heart disease. That’s why LDL cholesterol is often called “bad” cholesterol. Lower levels of LDL cholesterol reflect a lower risk of heart disease. When too much LDL cholesterol circulates in the blood, it can slowly build up in the walls of the arteries that feed 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. If a clot (thrombus) forms where a plaque is, the blood flow can be blocked to part of the heart muscle, causing a heart attack. If a clot blocks blood flow to part of the brain, a stroke results.
Bad” cholesterol – (LDL) cholesterol
Low-density lipoprotein, or LDL cholesterol, is known as “bad cholesterol.” Excess LDL builds up in your arteries and may lead toheart disease. The higher the level of LDL, the higher your risk for heart disease. Lowering elevated LDL cholesterol can reduce the risk of developing heart disease.

Why is HDL cholesterol considered “good”?

About one-third to one-fourth of blood cholesterol is carried by high-density lipoprotein (HDL). HDL cholesterol is known as the “good” cholesterol because a high level of HDL cholesterol seems to protect against heart attack. Medical experts think that HDL tends to carry cholesterol away from the arteries and back to the liver, where it is passed from the body. Some experts believe that excess cholesterol is removed from atherosclerotic plaque by HDL, thus slowing the build-up. However, low HDL cholesterol levels (lower than 35 mg/dL) may result in a greater risk for heart disease.

Good” cholesterol – (HDL) cholesterol
High-density lipoprotein, or HDL cholesterol, is called “good cholesterol” because it is believed to remove cholesterol from the blood. High levels of HDL in your blood may help to reduce your risk of coronary heart disease. A low HDL level can increase your risk.

Triglycerides

Another type of fat carried in your blood that maybe you haven’t heard of is known as triglycerides. Most of the body’s fat tissue is in the form of triglycerides, stored for use as energy. Triglycerides are obtained primarily from fat in foods. High triglyceride levels may increase your risk of heart disease.
Like choresterol triglycerides are common types of fats (lipids) that are essential for good health when present in normal amounts. They account for about 95 percent of the body’s fatty tissue. Triglycerides are present in food as well as manufactured by the body.Abnormally high triglyceride levels are associated with a number of diseases and conditions, such as cirrhosis (a disease of the liver), underactive thyroid gland diabetes and pancreatitis (inflammation of the pancreas).

High triglyceride levels are also associated with known risk factories for heart disease such as low levels of HDL (“good”)cholesterol , high levels of LDL (“bad”) cholesterol and obesity Additionally, triglycerides may contribute to a type of thickening of artery walls, a physical change believed to be a predictor of hardening of the arteries .

Blood Colesterol and Dietary Colesterol

It may surprise you to know that our bodies make all the cholesterol we need. When your doctor takes a blood test to measure your cholesterol level, the doctor is actually measuring the amount of circulating cholesterol in your blood, or your blood cholesterol level. About 85 percent of your blood cholesterol level is endogenous, which means it is produced by your body. The other 15 percent or so comes from an external source — your diet. Your dietary cholesterol originates from meat, poultry, fish, seafood and dairy products. It’s possible for some people to eat foods high in cholesterol and still have low blood cholesterol levels. Likewise, it’s possible to eat foods low in cholesterol and have a high blood cholesterol level.
So, why is there so much talk about cholesterol in our diet? It’s because the level of cholesterol already present in your blood can be increased by high consumption of cholesterol and saturated fat in your diet. This increase in dietary cholesterol has been associated with atherosclerosis ; the build-up of plaques that can narrow or block blood vessels. (Think about what happens to your kitchen drain pipes when you pour chicken fat down the sink.) If the coronary arteries of the heart become blocked, a heart attack can occur. The blocked artery can also develop rough edges. This can cause plaques to break off and travel, obstructing blood vessels elsewhere in the body. A blocked blood vessel in the brain can trigger a stroke.

Sources: Heart Health IVillage, For colesterol, Vytorin.

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