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joi, 19 mai 2011

The Highs and Lows of Cholesterol

Of all the risk factors for cardiovascular disease, high blood cholesterol takes the cake. Even the slightest elevation of certain types of cholesterol can put blood vessels at risk for dangerous and sometimes deadly narrowing. It is estimated that 8% of Americans have no idea they have a cholesterol problem; they are a ticking time bomb because a heart attack or stroke may already be in the works. Learn the numbers that tell you where you stand.

Of all the substances in the human body, cholesterol is one of the most critical to human existence. One hundred years of research has been dedicated to this ubiquitous compound. It is found in the membrane of every human cell, it protects our nerves and it is necessary for the manufacture of vital hormones, vitamins and substances that aid digestion. It would probably be the end of the story if it weren't for one problem – it can also kill.

News of cholesterol's dark side surfaced at the beginning of the 1900s when a German chemist Adolph Windaus discovered that the concentrations of this fatty substance were 20 times higher in narrowed aortas – the largest artery in the body – than in non-narrowed vessels. Decades later it was clear that cholesterol could also collect inside vessels supplying the heart and brain. Today the link between blood cholesterol, heart attack and stroke is undeniable, and the medical community has been keenly obsessed with finding ways to straighten cholesterol levels ever since.

Measuring cholesterol in the blood can help predict who is more likely to have a fatal event. The numbers are so important doctors urge patients to treat them as one of the body's security codes. Because along with reducing obesity, high blood pressure, diabetes and smoking, normalizing one’s cholesterol can be the difference between life and death.

Cholesterol is a fatty substance that is used to make steroid hormones such as estrogen, testosterone and the stress hormone cortisol. It's needed to make bile salts, a necessary component for digestion of fats, and it allows liquids and gases to go in and out of a cell's membrane. It also helps make vitamin D.

There are 2 sources of cholesterol, the cholesterol you make and the cholesterol you eat. The body produces about 75% of cholesterol, mostly in the liver. The rest comes from food.

Since blood is mostly water, and cholesterol is fat, it needs help getting to where it needs to go, so it hitches a ride on lipoproteins. There are 3 cholesterol-carrying lipoproteins that are particularly important. These are the ones you and your doctors should keep close tabs on.

Low-density lipoprotein (LDL) is the lousy type because it isn't very good at its job. It tends to hang inside of arteries and that can narrow or block the flow of blood. At first LDL just lays down fatty streaks, then over time, it gets thicker and harder turning into plaque. Plaque can become unstable and flake away. It also damages the vessel's lining which triggers a chain of chemical events that makes it ripe for clot formation and inflammation, another risk for heart disease. Blood vessels stiffen, making them less able to respond to changes in blood pressure and get blood where it needs to go.

The higher the level of LDL in the blood, the greater the risk for cardiovascular disease and stroke. The less "lousy" LDL in the blood, the better.

High-density lipoprotein (HDL) however, is the healthy type of cholesterol. It takes its job more seriously. It moves cholesterol around nicely from other parts of the body to the liver where it is discarded or recycled as needed. The more "healthy" HDL, the better.

Very low-density lipoprotein (VLDL) carrying triglycerides is another blood lipid that is used as a high-risk marker. Like LDL, it can negatively impact cardiovascular health.

How do you know your cholesterol situation?

There are some hints that could suggest cholesterol problems; for example, the presence of yellow fatty cholesterol lumps on the skin of the eyelids (xanthelasma), elbow or knees, or the inability to reach your toes with a straightened leg, a maneuver that could indicate blood vessels are stiffened by plaque. But mostly, people with abnormal cholesterol levels don't look or feel sick.

The only way to know is to measure cholesterol in the blood. A lipid profile is an estimation of LDL, HDL, triglyceride and total cholesterol. This will let you know where you stand along the risk spectrum.

Everyone over the age of 20 should get a blood lipid profile at least once every 5 years, more often if you have risk factors for heart disease or have been diagnosed with high cholesterol before. A small sample of blood is removed with a needle or finger stick after a 9-12 hour fast. Taking the test during any illnesses, infection, pregnancy, or after recent weight loss, surgery, trauma, stressful event or change in usual diet may skew the results. It's best to wait 6 weeks to stabilize. Women should arrange to get the test a few days after ovulation when estrogen and LDL levels are lowest. Some medications such as anabolic steroids, beta-blockers and oral contraceptives can increase cholesterol levels. Cholesterol levels can fluctuate so it is best to repeat the test several weeks to months apart before beginning medication.

LDL Values

Optimal – Less than 100 mg/dL
Near optimal – 100–129 mg/dL
Borderline high – 130–159 mg/dL
Risky – 160 –189 mg/dL
Very risky – 190 mg/dL and above

HDL Values
Optimal – 60 mg/dL and above
Borderline – 40–59 mg/dL
Risky – 40 mg/dL and below

Triglyceride Values

Optimal – 150 mg/dL or lower
Borderline – 150–199 mg/dL
Risky – 200–499 mg/dL
Very Risky – 500 mg/dL or higher

Total Cholesterol Values (this number alone is not a good gauge of cholesterol health)
Optimal – Less than 200 mg/dL
Borderline high – 200–239 mg/dL
Risky – 240 mg/dL and above

What can be done to normalize cholesterol?

LDL cholesterol is the most worrisome because even when LDL is slightly elevated, blood vessel narrowing occurs. And if is very high, it deposits much faster. Treatment is primarily focused on lowering LDL to an optimal level.

The first stop is adopting a healthy lifestyle and this includes the usual approaches:
Maintaining a health weight, BMI and waist circumference. Losing just 10 lbs can reduce LDL up to 8%. 
Engaging in a regular program of daily exercise. 
Reducing stress
And stopping smoking

Above that, people with abnormal cholesterol should eat less of the foods that increase LDL, and eat more that lower it. There is no good and bad dietary cholesterol. It is all just cholesterol.

Here are some food rules for people with high LDL:
Reduce intake of saturated fats to less than 7% of your total calories. These fats are found in animal products – butter, meat, eggs, whole milk dairy and cheese products – and certain oils, processed foods and baked goods. Reducing saturated fat can reduce LDL by up to 10%.
Don't eat more than 200 mg of cholesterol a day. It creeps up quickly so do your math. (The average American diet contains 400 mg of cholesterol a day.)
Eat more LDL-lowering foods like plant sterols and stanols (found in many grains, fruits, vegetables, nuts, seeds and sterol/stanol enriched products) and soluble fiber like oatmeal, psyllium and bran. Eating the leafy green purslane, and the Goji berry fruit might also have cholesterol-lowering effects.
Limit salt and sugar.

Strict adherence to the Therapeutic Lifestyles Changes (TLC) diet designed by the National Heart, Lung, and Blood Institute of the National Institutes of Health can reduce LDL cholesterol 30%, equal to that offered by medication.

Medication Approaches

For people who are unable to control cholesterol with diet or have other risk factors for heart disease – such as cigarette smoking, high blood pressure, the need for blood pressure medication, or a family history of heart disease – medications might be necessary.

The most popular cholesterol-lowering drug class called statins work by stopping a key enzyme involved in the making cholesterol. (Some studies show that the supplement red yeast rice (Monascus purpureus) may work similarly to lower cholesterol.) Other drugs work to decrease absorption, breakdown or elimination of cholesterol in the body. Some lipid-lowering agents are combined with other medicines for heart disease.

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