Cholesterol - the benefits of exercise and medication
By Dr. Nicholas Browning
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12:01 a.m. PT Apr 25, 2008
In my last two columns I talked about the health risks of elevated cholesterol and the effects of diet and supplements. In the next columns on cholesterol, I'll discuss the effects of exercise and prescription drug therapy.
For the purposes of controlling cholesterol, exercise unfortunately falls a little flat. It does raise HDL (good cholesterol) somewhat, but only when the exercise is relatively intense and prolonged. In other words, if you keep your heart rate above 100-110 for at least 20 minutes (40 would be better) four times a week, you can modestly raise your HDL cholesterol by 2-4 points.
I do want to say that some folks have come away from my columns wondering if exercise does them any good. Let me be very clear on this subject - you will live longer, better, and have less disease and disability if you exercise, regardless of its effects on cholesterol and weight. Fit people live longer than unfit people compared across weight groups.
Exercise has a wealth of positive effects that are independent of the effects on weight and cholesterol. I highly recommend at least 30 minutes of exercise at least three times a week, and more if you can. You literally have nothing better to do, trust me!
There are several classes of medications available for the control of cholesterol: cholesterol absorption inhibitors, bile acid sequestrants, fibric acid derivates, niacin products, and statins. I'll go over each one in some detail in the next few columns.
The only cholesterol absorption inhibitor currently on the market is Zetia (ezetimibe). It is available in combination with simvastatin as Vytorin. Zetia works by blocking cholesterol absorption from the intestine, causing elimination of cholesterol in feces with a drop in LDL (bad cholesterol) cholesterol levels. Zetia has been in the news lately because a large trial (named ENHANCE) showed no difference between patients taking it versus patients not taking it.
Keep in mind that the patients in this trial were not typical patients in that they had a genetic disorder causing increased cholesterol, and the study measured the thickness of a part of the carotid artery. I think this trial illustrates a couple of things, the first being that you cannot generalize this study to ordinary patients easily. The second is that the thing they were measuring, thickness of the carotid artery, may have nothing at all to do with anything.
Recall that I have pointed out that you alter your lifestyle, take supplements, or take drugs with the goal of helping yourself live longer and better. No one is going to know or necessarily care about the thickness of his or her carotid artery. The trial in the news has NO data on what you would really care about, which is whether or not the drug kept people from having heart attacks or strokes.
I will discuss clinical trials in an upcoming article, but in a nutshell, clinical trials at this point are the best proof that we have of the effects of a medication or intervention. The best clinical trials have a lot of patients in them (several hundred to several thousand), randomize patients to one group that receives treatment and one group that receives placebo, follow patients for months or years, and look for meaningful differences.
The most important statistic to look for is a reduction in mortality. The next most important statistics are real things that matter, like reduction in heart attack or stroke rates. Things like carotid artery thickness and similar items aren't that meaningful. Lowering your cholesterol in and of itself seems to be a good idea, but the whole reason you are doing it is to live longer and not have a stroke or heart attack.
If a particular drug lowers your cholesterol but ends up causing you to die earlier then it has done you no good. Pfizer recently developed a drug that was very effective in raising HDL cholesterol but unfortunately it increased mortality rates and so will not be put on the market.
The bottom line is that you want the drugs you are taking to have meaningful reasons behind them. A drug can do a particular thing well like lower cholesterol, but if it doesn't reduce your risk of dying or reduce your risk of a bad outcome it may not do you any good at all.
Zetia at this time has no data on the reduction of mortality or prevention of heart attacks or stroke. It may be a useful addition to a regimen to limit the dose of a statin if side effects are intolerable at high doses, or if you are maxed out on a statin and wish to take something fairly well tolerated. Until more data come out, I cannot recommend taking Zetia for most patients for the purpose of lowering your cholesterol, as it does not have mortality data. You should NOT discontinue the drug if you are taking it currently until you speak with your doctor. You and your doctor may have good reasons that I am not aware of for you to keep on taking it.
You can search HYPERLINK "http://www.theunion.com" www.theunion.com for prior articles in this series as well as other columns. Please feel free to email with questions or suggestions for future topics at nicholas.browningmd@gmail.com
