High Cholesterol

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 process related to problems with cholesterol transport.

When it comes to LDL, size matters

The most dangerous situation is when cholesterol is transported in a barrage of small, dense LDL particles that can slip through the cracks and congregate within the arterial wall. Numerous studies have shown that when one reverses the lipoprotein transport patterns - from a dangerous pattern of small, heavy LDL particles to a heart - healthy pattern of very few large and fluffy LDL particles - there is significantly less risk of heart attack. The steps in the Cholesterol Down Plan will help alter the size and shape of your LDL particles for maximum heart protection.

Number your doctor will be concerned about

     • High total cholesterol. This number reflects the total amount of cholesterol found in all the lipoproteins (LDL, HDL, VLDL) circulating in the blood. According to the American Heart Association, a value of less than 200 mg/dL is desirable for a relatively low risk of heart disease.

     • Low HDL. To keep your heart and blood vessels in top shape, it is beneficial to have as high a concentration of HDL particles in the blood as possible. Too low an amount is unhealthy. According to the American Heart Association, a value of less than 40 mg/dL heightens your risk of heart disease.

     • High LDL. The higher your LDL, the higher your risk of heart and vessel disease. As you will learn, LDL is the most telltale sign of risk. According to the American Heart Association, an optimal level of LDL cholesterol is less than 100 mg/dL.

     • High triglyceride. Your triglyceride value reflects the amount of blood fats circulating. A high number is also a risk factor for heart disease. According to the American Heart Association, a normal triglyceride level is less than 150 mg/dL.

     • High ratio of total cholesterol to HDL. Some physicians use the ratio of total cholesterol to HDL cholesterol to determine risk for heart disease. A high number means there is too little "good" cholesterol and too much "bad" cholesterol. According to the American Heart Association, the optimal ratio is 3:5:1 or less.

Source: American Heart Association, http://www.americanheart.org/presenter.jhtml?identifier=183

                                                                                HDL, the lifesaving lipoprotein

HDL is manufactured in the small intestine and the liver, its primary source. As it moves though the bloodstream, it takes in excess cholesterol that leaches out of tissue cells and, most important, excess cholesterol building up in the inner arterial wall. HDLs unload this cholesterol in the liver, where it is then excreted via bile, a process referred to as "reverse cholesterol transport." Other lipoproteins bring cholesterol into the cells, so it is this reverse transport from the cells to the liver that distinguishes HDL as the "good" cholesterol. An elevated level of HDL has been associated with a reduced risk for heart disease. HDL confers heart - protective benefits in four ways.

1. HDL circulates around the body, picking up excess cholesterol and bringing it back to the liver for disposal (reverse cholesterol transport).

2. HDL is an antioxidant, capable of dismantling rogue free radical molecules that oxidize the protein in the LDL particles - a contributing factor to atherosclerosis. (Oxidation is the same process that produces rust on metals.)

3. HDL exhibits anti-inflammatory activity (like aspirin) and can decrease the inflammation linked with the atherosclerosis process.

4. HDL lessens the ability of the blood to form clots, thus reducing the risk of heart attack or stroke.

HDL VS. LDL: A COMPARISON
	HDL "Good" Cholesterol	LDL "Bad" Cholesterol

What it is composed of	Mostly protein, some cholesterol and phospholipids, very little fat	Mostly cholesterol, a moderate amount of protein and phospholipids, and some fat
Where it is produced	Almost all HDL is formed in liver cells, with a small quantity produced by intestinal cells	Cells of the liver and intestine produce VLDL, LDL evolves from VLDL
Where it is found	In the bloodstream and inner arterial wall	In the bloodstream and inner arterial wall
Direction of transport	From the cells of the body to the liver	Initially from the liver (as VLDL) to all cells throughout the body
Effect on the arteries leading to the heart and brain	Protects against the development of atherosclerosis	Promotes the development of atherosclerosis
Effect of quantity on heart health	Low amount is a risk factor fro heart disease	High amount is a risk factor for heart disease
Optimal particle size	Larger-sized HDL particles (HDL2b) are most protective (indicating active reverse cholesterol transport)	Larger-sized LDL particles are desirable, as small, dense LDL particles increase risk of atherosclerosis
Optimal amount	Greater than 40 mg/dL, the higher the better	Less than 100 mg/dL, the lower the better

LDL, the deadly lipoprotein

LDL is the chief cholesterol carrier in the blood, ferrying approximately 70 percent of all the blood cholesterol around the network of arteries. Basically, this lipoprotein is loaded with cholesterol. Unlike HDL, LDL is not directly manufactured in the liver. Instead, a different type of lipoprotein is first produced by the liver, the parent lipoprotein called VLDL. After circulating around the bloodstream, VLDL loses much of its fat (triglyceride) cache to various bodily cells to become LDL. LDL is designed to take cholesterol to cells that have run short, as cells require some cholesterol to maintain proper functioning. Typically, the LDL is taken into the cell and broken down, and then the cholesterol is used to make membranes or hormones. However, when the amount of LDL in the blood gets too high, the situation can become injurious.

Why is LDL so dangerous?

LDL is commonly referred to as the "bad" cholesterol because high levels of circulating LDL have been linked to an increased risk for atherosclerosis and cardiovascular disease. LDL is the most dangerous lipoprotein, not only because each particle is made up of mostly cholesterol (roughly 45 percent) but also because of its destination. LDL carries cholesterol to the arteries, infiltrates their walls, and goes through a series of transformation that trigger plaque buildup.

Source: Cholesterol Down, Foreword by Jennifer H. Mieres, M.D.