Cholesterol

Overview

Cholesterol is a waxy, fat-like substance that's found in all the cells in your body. Your body needs some cholesterol to make hormones, vitamin D, and substances that help you digest foods. Your body makes all the cholesterol it needs. Cholesterol is also found in foods from animal sources, such as egg yolks, meat, and cheese.

Structure

Cholesterol is a sterol (a combination of steroid and alcohol) and a lipid, meaning that it is a relatively large molecule made up of a large number of smaller components. In the case of cholesterol, these components include a complex ring structure with a hydrocarbon tail. The size and shape of the molecule prevent it from dissolving in water and blood, a characteristic important to its function.

Function

Cholesterol has four primary functions, each of which is essential to your body's cells. It contributes to the structure of cell walls, makes up digestive bile acids in the intestine, allows the body to produce vitamin D, and enables the body to make certain hormones.

Biosynthesis

Cholesterol is produced in the body mainly in the liver. The process involves a series of enzymatic reactions that convert acetyl-CoA into cholesterol. This process is tightly regulated to ensure that the body produces just the right amount of cholesterol.

Transport

Cholesterol travels through your bloodstream in small packages called lipoproteins. These packages are made of fat (lipid) on the inside and proteins on the outside. Two kinds of lipoproteins carry cholesterol throughout your body: low-density lipoproteins (LDL) and high-density lipoproteins (HDL). Having healthy levels of both types of lipoproteins is important.

Dietary Sources

Cholesterol is found in animal-based foods, including meat, eggs, and dairy products. Plant-based foods, such as fruits, vegetables, and grains, do not contain cholesterol.

Health Implications

High levels of cholesterol in the blood can increase your risk of heart disease. When there is too much cholesterol in your blood, it can build up on the walls of your arteries, forming a hard, thick substance called plaque. Over time, this plaque can narrow your arteries and make them less flexible, a condition known as atherosclerosis.

Treatment and Prevention

A combination of healthy diet, regular exercise, and sometimes medication can help reduce high cholesterol. It's important to keep your cholesterol in check because high cholesterol levels can lead to heart disease, heart attack, and stroke.