by Peggy Spencer
Daily Lobo columnist
Dear Dr. Peg,
In a recent TV commercial, the makers of a certain drug claimed that their medicine raises good cholesterol by up to 14 percent and lowers bad cholesterol simultaneously. Their ad slogan is "down with the bad, up with the good." What is the difference between good and bad cholesterol?
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Dear Slogan Challenger,
Strictly speaking, all cholesterol is the same. The descriptors "good" and "bad" are a kind of shorthand that actually refer to the protein molecules that carry cholesterol. We'll get to those in a minute. Cholesterol itself is one of the building blocks of life. It repairs cell membranes, makes hormones and helps manufacture vitamin D, among other functions. Without it, we'd be skinless and brainless. In short, we wouldn't be. We need it. In fact, most of our body's cholesterol is homemade, right in our own liver.
So, what's the fuss? It's a matter of degree and distribution. Too much cholesterol in the wrong places can be deadly. This brings us back to those protein molecules. Cholesterol-carrying proteins are called lipoproteins. The two we're interested in are called LDL and HDL.
LDL, or low-density lipoprotein, is the bad guy. This lowdown character carries cholesterol from the liver factory to the tissues and deposits it there. Sometimes, that causes trouble, as we'll see. HDL stands for high-density lipoprotein, the high and mighty cleaner-upper that clears cholesterol out of places it doesn't belong and hauls it back to the liver.
Indulge me in a loose metaphor. Imagine your blood vessels are like a network of underground tunnels. The tunnels are full of busy little Disney dwarves in two crews. The LDL crew has wheelbarrows. The HDL crew has shovels. The LDLs load up with cholesterol in the liver and roll through the tunnels. Imagine cholesterol as sticky, globby bricks. Every so often, a wheelbarrow tips, as wheelbarrows will, and a sticky brick falls out. Along comes an HDL with a shovel, scooping up the brick and carrying it back to the liver. So far,
so good.
However, we all know a wheelbarrow will trump a shovel every time. In other words, the HDLs may not keep up. If the sticky brick isn't scooped up, it causes a bump in the road, over which further barrows will bumble, dropping their bricks or busting an axle and adding to the debris. Local cleanup crews from the immune system try to help, but they end up sticking to the bricks. The result is a messy clump that clogs the tunnel and slows traffic.
In reality, of course, the tunnels are arteries with oxygen-carrying blood flowing through them. The messy clump is called a plaque. Plaques block the flow of blood. If an artery is clogged, the blood can't get to its destination as easily. Downstream tissues, starved of their essential oxygen and nutrients, will suffer. That's called atherosclerotic disease, or hardening of the arteries. If the artery gets blocked enough, the downstream tissue can actually die. If this happens in the tiny arteries that feed the heart muscle, it's called a heart attack. The other way a heart attack happens is when a piece of the plaque breaks off and floats downstream into a smaller artery, blocking it completely.
The good news is you have some control over this fiasco. You can stock up on shovels and retire some wheelbarrows. But first you need to know where you stand now. Everyone who is 20 or older should have a blood test called a fasting lipid profile. The lab measures the levels of LDL and HDL in your blood, in addition to the levels of cholesterol and another lipid called triglyceride. What you hope for is high levels of HDL and low levels of everything else.
If you don't get the results you were hoping for, increasing your aerobic exercise can increase your HDL, as can a drink or two of alcohol daily. Decreasing the amount of animal fat in your diet can lower your LDL. The liver needs saturated animal fats to make cholesterol. A heart-healthy diet also includes high-fiber foods and lots of fresh fruits and vegetables. For further heart protection, don't smoke, and keep your weight in a normal range.
Heart disease caused by plaque is the No. 1 killer in this country. Drugs like the one in the commercial you saw are widely prescribed. They are called statins, and yes, they can alter the balance of good and bad cholesterol, or HDL and LDL. If you take proactive steps now, and make some wise decisions about what you do with your body and what you put into it, you may never need one. Start with a call to the Student Health Center at 277-3136 for an appointment to get your lipids checked.
Peggy Spencer has been a UNM student health physician for 16 years. E-mail your questions to her directly at Pspencer@unm.edu. All questions will be considered, and all questioners will remain anonymous. This column has only general health information and cannot replace a visit to a health provider.
