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The ABCs of Cholesterol

August 11, 2002|by KEVIN CLAPP

kevinc@herald-mail.com

OK, let's get this straight:

We've got our LDL, HDL and VLDL. These lipoproteins chauffeur fats around the body, and when triglycerides are shed by VLDL, VLDL becomes LDL.

HDL, which carries fats back to the liver, trumps LDL. LDL, bad seed that it is, is more prevalent than HDL. And doctors say very high LDL coupled with too low HDL should be taken care of ASAP, PDQ and with no ifs, ands or buts.

Huh?

Talk about your sticky wickets, an alphabet soup brain teaser, a big fuss wrapped around an odorless, soft, waxy substance the body already creates in addition to what we take in by eating animal products.

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Like so many things (flossing, on-time oil changes), monitoring cholesterol can be a bother, an easily dismissed nuisance swatted away to make room for 'more important things.'

But for 41.3 million American adults whose cholesterol is high as a kite, it's important to pay attention. Physicians have long identified elevated levels as a risk factor for heart disease and attack. And even though a recent Associated Press report that 50 percent of all heart attacks occur in people with normal or low readings, diligent monitoring of cholesterol levels is still required. "We need cholesterol," says Rudy Santos, M.D., with Potomac Internal Medicine in Waynesboro, Pa. "But too much of it is bad."

Physicians recommend cholesterol level checks beginning at age 20 and every five years after for those with normal readings, more often when elevations are detected.

But what does it all mean? Let's break it down and find out.




In the beginning



Cholesterol is everywhere in the body, a component used to form cell membranes and hormones. And it is naturally occurring in the body, originating in the liver.

Tim Higgins, Washington County Health System clinical nutrition manager, says up to nine-tenths of cholesterol can be generated by the liver.

Carried through the body by lipoproteins classified by density, cholesterol comes in three packages:

Low-density lipoproteins (LDL) carry most cholesterol through the body. Along the way, cholesterol particles are deposited on the walls of arteries; and LDL oxidizes, shedding molecules that mix with other substances and form plaque.

High-density lipoproteins (HDL) comprise between one-third and one-fourth of cholesterol running through the body. According to the American Heart Association, HDL serves in part as a street-sweeper of the arteries, whisking away excess cholesterol from plaque and taking it back to the liver to be passed out of the body.

Very low-density lipoproteins (VLDL) transport cholesterol and triglycerides from the liver. Once triglycerides, where fat is stored until converted to energy, are deposited in the body, VLDL becomes LDL.

Think of LDL as bad, like the accumulation of litter along a highway. HDL, on the other hand, is good, riding in to the rescue like a white knight to clean up the streets.

Confusing matters is the fact that some people have a genetic predisposition to creating excess cholesterol. Cardiologist Frederick Kuhn says these patients add insult to injury by chowing down on an unhealthy diet.

"Being genetically predisposed is not a license to misbehave," says Kuhn, with St. Agnes Health Care in Baltimore. "So generally, those people will have to resort to a cholesterol lowering medication."

In a report published in the May issue of Scientific American, Peter Libby, M.D., chief of cardiovascular medicine at Brigham and Women's Hospital in Boston, wrote about the increasing role inflammation plays in triggering atherosclerosis.

As important a role as cholesterol plays in heart attack, some medical experts, including Dr. Paul Ridker at Brigham and Women's, say inflammation dwarfs it. A group of physicians plans to publish results of a study on inflammation and what physicians should be checking for to fight it in November.

One thought permeating this new debate is the role played by what is called C-reactive protein, a chemical in the body Kuhn says is released by cells to combat inflammation. The theory is that a test for the level of C-reactive protein in the body is a better indicator of heart problems than cholesterol. Still, Libby did not acquit cholesterol for its role in facilitating heart disease and attack. He wrote that LDL can spur arterial inflammation and that, similarly, the threat may be reduced by taking cholesterol-lowering treatments.

Cholesterol reducing drugs (statins, bile acid resins, nicotonic acid and fibrates) work to lower the levels of fats in the blood, either by inhibiting the natural production of cholesterol or by preventing reabsorption of cholesterol into the bloodstream from the liver, ensuring the body expels cholesterol without recycling it through the bloodstream.

The risk of side effects from taking the drugs is low, but Santos in Waynesboro says side effects can include headaches, diarrhea, nausea and becoming flush in the face or neck.

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