Lipid Dysfunction: High Cholesterol and Its Effects

High Cholesterol, hyperlipidemia, hypercholesterolemia, dyslipidemia - while not completely interchangeable, they're all commonly used to refer to the same problem. High cholesterol, however is actually a misnomer. There are two types of cholesterol, high-density lipoprotien (HDL) and low-density lipoprotein (LDL) (Technically there is a third "very low density lipoprotein," but for the purposes of this discussion, we're going to include them in the LDL). LDL is the "bad" cholesterol and when the doctor refers to patient as having high cholesterol, this is the number that they're worried about. HDL is good cholesterol and doctors typically want this number to be high.

Lipoproteins are structures in the blood made of a particular type of lipid known as a phospholipid. Lipids are not soluble in water, which is the primary component of blood, but lipoproteins are... and they can carry the fat particles around the body. Lipid disorders occur when there are too many "bad" lipids in the body.

Why We Need Cholesterol
Cholesterol is a necessary substance in the body. It is the base of many of the body's hormones (including the sex hormones testosterone, estrogen and progesterone). It is the basis of bile, a emulsifier that is released into the small intestine to help us to digest fats properly (otherwise we would have diarrhea every time we ate a meal with any fat in it). Cholesterol also helps us store fat between meals.

Causes of Lipid Dysfunction
There are many secondary causes of lipid dysfunction, like obesity, smoking, alcoholism and hypothyroidism but those are generally dealt with by treating the underlying condition. Certain medications can cause lipid dysfunction, too, like birth control pills and estrogens, corticosteroids, some diuretics, beta blockers, and even some antidepressants. But the two major contributing factors to primary lipid dysfunction is genetics and diet.

The liver makes a portion of the cholesterol that is needed on a daily basis. In some people, it makes more than is healthy. When internally-made cholesterol levels are too high, it may be prudent to decrease cholesterol levels. Sometimes that is all that is needed to maintain a healthy lifestyle, and other times, medications are needed.

Dietary sources of cholesterol are, not surprisingly, usually sources of fat as well. Elk yolks, butter, beef kidneys and livers, and fried foods of all sorts are all sources of cholesterol. The American Heart Association recommends no more than 300mg of cholesterol in a day. A single egg contains 225mg, mostly in the yolk. So most Americans consume well over their necessary cholesterol requirement in a single day.

Symptoms and Consequences of Lipid Dysfunction
High cholesterol contributes to atherosclerosis, a stiffening of the arteries that contributes to hypertension. It also lead to partial or complete blockages of arteries. If coronary arteries are blocked, the result is a heart attack.

Unfortunately, even advanced stages of high cholesterol have few symptoms other than those of the hypertension they cause. That's why it is important for patients to get regular blood tests for cholesterol levels.

Treatment of High Cholesterol
The first line of treatment, as in most cases, is lifestyle changes - decreasing cholesterol intake and increasing exercise. If the high cholesterol is caused by secondary factors, like drinking or smoking, then quitting is ideal.

• HMG-CoA Reductase Inhibitors - Pharmaceutically, this is usually the first choice for the treatment of high cholesterol. They disable a liver enzyme (HMG-CoA Reductase) that is responsible for the production of cholesterol.
• Fenofibric Acid Derivatives (Fibrates) - Disables a receptor (PPAR-alpha) in certain tissues in the body, including muscle tissues, which causes the liver to create more HDL and to begin beta oxidation, the use of fat as a fuel. They also increase clearance of already-circulating cholesterol.
• Bile acid sequestrants - Works primarily in the intestines work primarily in the intestinal tract to prevent the absorption of dietary cholesterol.

Other agents, including fish oil, Omega-3 Fatty Acids, niacin and ezetimibe will be covered in more detail later, as they work through a number of different means and don't fall into a neat category.

Until next time,
C. Samuels

Resources

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"High Cholesterol Foods." all-about-lowering-cholesterol.com. all-about-lowering-cholesterol.com, n.d. Web. 5 Jun 2011. <http://www.all-about-lowering-cholesterol.com/high-cholesterol-foods.html>.


Wikipedia contributors. "Fibrate." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 23 Mar. 2011. Web. 6 Jun. 2011.


Wikipedia contributors. "Hypercholesterolemia." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 3 Jun. 2011. Web. 6 Jun. 2011.


Wikipedia contributors. "Statin." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 3 Jun. 2011. Web. 6 Jun. 2011.