What is the difference between "good" cholesterol and "bad" cholesterol? Why do we have cholesterol, anyway?

Join Our Community of Science Lovers!

Laura Andersson, a visiting professor of chemistry at Vassar College in Poughkeepsie, N.Y., answered as follows:

What people refer to as good cholesterol and bad cholesterol are not really cholesterol at all. They are actually carrier proteins that act like "baskets" to transport cholesterol between the blood and the liver. The "bad" form is low-density lipoprotein, which carries cholesterol from the liver, where it is made, to the blood. It is considered bad because too much cholesterol in the blood slowly clogs arteries, eventually causing heart disease. On the other hand, what is termed "good" cholesterol is a high-density lipoprotein that transports cholesterol from the blood to the liver.

Your body makes cholesterol because it is a building block for a number of essential substances. These include:

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

Pre-vitamin D, which
is converted by sunlight to vitamin D
Testosterone, the "male" sex hormone
Estrogen, the "female" sex hormone
Progesterone, a
sex hormone found in both males and females
Bile salts, that nasty yellow stuff that comes up with severe nausea
Other critical steroid
hormones that help to regulate such important things as potassium and sodium levels

Excess cholesterol is "stored" in the blood. The actual cholesterol levels are determined by a number of factors, including heredity, diet and exercise. Diet appears to be the most important of these.

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American