Exercise to lower cholesterol

The exercise-cholesterol link

Researchers aren't entirely sure how exercise lowers cholesterol, but they are beginning to have a clearer idea. Lots of people, even many GPs, assume that exercise lowers cholesterol, but until recently, most of us weren't sure just what the connection was.

One way exercise can help lower cholesterol is by helping you lose -- or maintain -- weight. Being overweight tends to increase the amount of low-density lipoprotein (LDL) in your blood, the kind of lipoprotein that's linked to heart disease.

Part of the confusion about the effect of exercise on cholesterol stems from the fact that most early cholesterol studies focused on both exercise and dietary changes, making it hard to tease out which of these factors was actually making the difference. But recent studies have more carefully examined the effect of exercise alone, making it easier to evaluate the relationship between exercise and cholesterol.

Researchers now believe there are several mechanisms involved. First, exercise stimulates enzymes that help move LDL from the blood (and blood-vessel walls) to the liver. From there, the cholesterol is converted into bile (for digestion) or excreted. So the more you exercise, the more LDL your body expels.

Second, exercise increases the size of the protein particles that carry cholesterol through the blood. (The combination of protein particles and cholesterol are called "lipoproteins;" it's the LDLs that have been linked to heart disease). Some of those particles are small and dense; some are big and fluffy. The small, dense particles are more dangerous than the big, fluffy ones because the smaller ones can squeeze into the [linings of the heart and blood vessels] and set up shop there. But now it appears that exercise increases the size of the protein particles that carry both good and bad lipoproteins.

How much exercise does it take to lower cholesterol?

Exactly how much exercise is needed to lower cholesterol has been a matter of some debate. In general, most public health organisations recommend, at a minimum, 30 minutes per day of moderate to vigorous exercise, such as walking, jogging, cycling or gardening.

But a 2002 study by researchers at Duke University Medical Center found that more intense exercise is actually better than moderate exercise for lowering cholesterol. In a study of overweight, sedentary people who did not change their diet, the researchers found that those who got moderate exercise (the equivalent of 12 miles of walking or jogging per week) did lower their LDL level somewhat. But the people who did more vigorous exercise (the equivalent of 20 miles of jogging a week) lowered it even more.

The people who exercised vigorously also raised their levels of high-density lipoprotein (HDL) -- the "good" kind of lipoprotein that actually helps clear cholesterol from the blood. Researchers found it requires a good amount of high intensity exercise to significantly change HDL and walking is not enough.

According to the findings, however, even though moderate exercise was not as effective in reducing LDL or increasing HDL, it did keep cholesterol levels from rising.

Therefore, some exercise is better than none; more exercise is better than some.