Metabolism of Cholesterol

Cholesterol is a type of lipid, or fat molecule. It is involved in the production of vitamin D and the manufacture of bile. In this respect, cholesterol is very important to the body. However, excess blood cholesterol has been linked to cardiovascular disease. As with any component of a healthy diet, moderation is key.

Digestion

• In the stomach, fat is separated from the rest of the food. It floats to the top of a watery solution called chyme. Once it reaches the small intestine, the gall bladder sends bile to emulsify the fat. Then, an enzyme from the pancreas, called lipase, begins digesting the fat.

Transportation

• Smaller particles of fat can be transported from the small intestine to the cells that need them just as they are. Larger pieces of triglycerides, phospholipids, and sterols must bind with a protein to create lipoproteins. When people discuss blood cholesterol levels, they often refer to LDL and HDL. These are low density lipoproteins, or those that contain more fat than protein, and high density lipoproteins, or those that contain more protein than fat.

Storage

• Cholesterol is transported to cells that need it by low density lipoproteins. Fats are stored in many places in the body to cushion vital organs and provide emergency energy reserves. Excess fat, including cholesterol, is carried away from body tissues on high density lipoproteins to be excreted.

Uses

• Some cholesterol is directed to the liver for the production of bile. Bile emulsifies fat, binding it to water to help digestion and transportation through watery membranes such as the small intestine. Cholesterol in the fatty layer under the skin plays an essential role in vitamin D production when exposed to sunlight.

Precautions

• Elevated blood levels of LDL, and low levels of HDL have been linked to risk of cardiovascular disease, which can lead to heart attack or stroke. A diet that is low in saturated fats and adequate in unsaturated fats helps keep the balance of LDL and HDL healthy.