What Is Cholesterol?

Learn how cholesterol works in the body and what it means to your health

I’m not your average doctor when it comes to cholesterol. Why? Because I don’t believe cholesterol is the villain it’s made out to be when it comes to heart disease. In fact, it’s not much of a risk factor at all.

The real cause of heart disease is inflammation, not cholesterol. I believe this is true because half of all people who die of heart attacks have a “normal” cholesterol level—and because of all the angiograms I’ve performed on patients with high cholesterol numbers but completely clean arteries.

Bottom line: The cholesterol connection just isn’t as strong as it’s made out to be by mainstream medicine and the pharmaceutical industry. That's why I co-authored The Great Cholesterol Myth with nutritionist Jonny Bowden, Ph.D.

What’s more—and possibly worse—is that they don’t tell you your body can’t function without cholesterol. For example, this vital substance is a waxy, fat-like material that your body needs to carry out many functions, which include:

• Synthesizing essential nutrients such as vitamin D; steroid hormones such as estrogen, progesterone, testosterone, and cortisol; and bile acids needed for digestion
• Constructing the semi-permeable membranes around each of the 100 trillion cells that make up your body
• Repairing damage that occurs within the cardiovascular system
• Facilitating cell communication and memory in the brain

The Scoop on LDL Cholesterol vs. HDL Cholesterol

Cholesterol moves through the body with the help of two proteins: LDL, or low-density lipoprotein, and HDL, or high-density lipoprotein. LDL carries ready-to-use cholesterol molecules that can be absorbed by cells that need it. Meanwhile, HDL picks up excess cholesterol and carries it back to the liver for recycling and excretion.

LDL and HDL work as a team, which is why it’s important to have the right balance of the two.

When the ratio of LDL cholesterol to HDL cholesterol falls out of balance—specifically when there is a lot more LDL than HDL—the excess LDL cholesterol essentially starts to rot. In the blood, the “rotting” process is called oxidation, and it happens when LDL cholesterol is attacked by free radicals from toxins such as mercury, trans fats, and insecticides, to mention a few.

The oxidation of LDL cholesterol is considered a pivotal step in the development of heart disease because oxidized LDL cholesterol particles can penetrate the endothelial cells lining the arteries, which contributes to—and accelerates—the inflammatory process. Over time, increased inflammation leads to the formation of arterial plaque buildup (atherosclerosis).

Cholesterol Ratios and Subtypes

Research over the past 50 years has repeatedly connected cardiovascular disease with out-of-balance cholesterol ratios.

A ratio of 5:1 or greater (LDL to HDL) has been associated with a higher risk of heart attack than a ratio less than 5:1. For example, if your LDL cholesterol is 150 mg/dL and your HDL is 50 mg/dL, your LDL to HDL ratio would be a healthy 3:1. Ideally, your HDL cholesterol should be 60 mg/dL or greater. At a minimum, men should be at 35 mg/dL and women at 40 mg/dL or more. Depending on your level of total cholesterol, you may need to reduce your LDL cholesterol levels and raise your HDL cholesterol levels so that your ratio of LDL to HDL is less than 5:1.

That said, achieving optimal cholesterol levels is far more complex than this. There are actually multiple subtypes of both LDL cholesterol and HDL cholesterol, and some of those subtypes are good and some are bad. So, it’s not just about how high your LDL cholesterol is. It’s about what kind of it you have, and how much. The same goes for HDL cholesterol. And to determine all of this, you need to go beyond the standard blood lipid tests that most doctors use to monitor cholesterol levels.

WATCH: Is Your Cholesterol Level in the Healthy Range?

More Dr. Sinatra Advice on Healthy Cholesterol

What are the different subtypes of LDL cholesterol and HDL cholesterol? Discover which kinds of cholesterol are most harmful.

What tests do you need to accurately assess your cholesterol levels? Find out which tests can flag the most dangerous subtypes of cholesterol.

Where do triglycerides fit into the picture? Learn about the importance of healthy triglyceride levels and how to achieve them.

Read questions and answers about cholesterol.