What is cholesterol?
Cholesterol belongs to the steroid family of lipid (fat) compounds. It’s a type of fat in your body and several of the foods you eat. While too much cholesterol isn’t a good thing, the body needs some cholesterol to run at its best. Cholesterol is the most abundant steroid in the body.
Lipids are fatlike substances that your body needs in small amounts. Chemically, lipids have many carbon and hydrogen atoms. The presence of these makes a lipid nonpolar. This means it doesn’t have an electrical charge at any end. Lipids won’t dissolve in water. They serve as an important energy source for the body.
Scientists divide lipids into several categories which then have further divisions. For example, there are fatty acids, glycerides, and non-glyceride lipids. Steroids belong in the non-glyceride lipids group along with:
- lipoproteins
- sphingolipids
- waxes
The next section will further examine the importance and chemical makeup of steroids like cholesterol in your body.
Scientists classify steroids by their chemical structure. Steroids’ chemical makeup includes a ring system. This includes three cyclohexanes and one cyclopentane.
In addition to these basic components, a steroid will have other functional groups attached. These molecular components cause one compound to be cholesterol, while another may be cortisone. In your body, all steroid hormones originally come from cholesterol.
Several different steroid types exist within the body or can be made in a lab. Examples include:
- aldosterone
- anabolic steroids
- birth control pills
- cortisone
- sex hormones, such as testosterone and estrogen
Cholesterol is also naturally present in many foods. Examples include dairy products, meat, and eggs. Some oils used in cooking may also stimulate the liver to make extra cholesterol. These oils include palm, palm kernel, and coconut oil. For this reason, doctors often recommend using these oils sparingly in cooking.
Sterols are a subgroup of steroids to which cholesterol belongs. Sterols are important not only to humans, but also to plants. For example, plants have cholesterol, too. The cholesterol in plants is used to make up the cell membrane. Doctors call sterols in plants phytosterols. Sterols present in animals are zoosterols.
Some types of plant sterols can lower cholesterol, especially in people who have high cholesterol levels. For example, plant sterols are naturally present in:
- whole grains
- fruits
- vegetables
- nuts and seeds
- legumes
These are all healthy foods that doctors usually recommend eating for good health.
In addition to being rich in nutrients and lower in calories, these foods contain sterols that can prevent cholesterol absorption in the digestive tract. As a result, the body eliminates them via the stool. Some food manufacturers even add plant sterols to foods like orange juice, margarine, and cereals to help people lower their cholesterol.
Cholesterol is a very important steroid to the body. It’s formed in the liver, brain tissue, bloodstream, and nerve tissue. It’s a precursor to certain hormones, such as testosterone. This means the body needs cholesterol to create these hormones.
Cholesterol is also an important component of bile salts. These help break down dietary fats. Cholesterol is in all cell membranes. Cell membranes provide structure in your body and protect the inside of the cell.
Doctors classify cholesterol into low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Doctors commonly call HDL cholesterol the “good” kind of cholesterol, because it circulates in the blood and removes excess, unwanted cholesterol.
LDL cholesterol is the type that can lead to buildup in the body’s arteries. Over time, these deposits can harden. This narrows the flow of blood through the vessels. The result is a condition known as atherosclerosis. It can cause conditions like high blood pressure, heart disease, and stroke.
A doctor can perform a blood test known as a lipid panel to determine if your blood cholesterol levels are too high or if you may be at risk for atherosclerosis. A doctor can review the results of your cholesterol test and compare it to people your age.
Cholesterol levels are measured in milligrams per deciliter of blood (md/dL). Here’s a breakdown of healthy cholesterol levels by age and sex:
| Age | Total Cholesterol | Non-HDL | LDL | HDL |
| Anyone 19 or younger | Less than 170 mg/dL | Less than 120 mg/dL | Less than 100 mg/dL | More than 45 mg/dL |
| Men 20 or older | 125-200 mg/dL | Less than 130 mg/dL | Less than 100 mg/dL | 40 mg/dL or higher |
| Women 20 or older | 125-200 mg/dL | Less than 130 mg/dL | Less than 100 mg/dL | 50 mg/dL or higher |
Your non-HDL is your total cholesterol minus your HDL measurement. It also includes other lipoproteins.
While cholesterol often gets a bad reputation as being harmful, this isn’t always the case. Cholesterol may be the most abundant steroid in your body. The body needs cholesterol to function.
Too much cholesterol via dietary fats can lead to harmful side effects, including heart disease. Ask your doctor if, or how often, you should be getting your cholesterol checked.