Lipids are fats. In the body they take the form of phospholipids, cholesterol and fatty acids. Although fats are usually associated with obesity and disease, your body needs a certain amount of fat to function -- also known as essential body fat. Men need at least 3 percent body fat and women need at least 12 percent body fat to ensure normal functioning. You get triglycerides and phospholipids from your diet, and you get cholesterol from your diet and your body also produces it naturally. The role that lipids play depends on the type of lipid.
Triglycerides
Triglycerides are also called blood and body fat. As body fat, triglycerides play a role in energy storage. They also provide a layer of insulation under the skin and protective cushioning around the organs. Your body also uses triglycerides to make the myelin sheaths that surround nerve cells. Myelin sheaths act as insulation and help the nerve signal travel faster along the length of the nerve. Triglycerides are solid at body temperature and are classified as saturated fats. If you have too much triglyceride in your blood, it can collect on the blood vessel walls and cause heart disease.
Cholesterol
Cholesterol is another type of blood fat. Your body uses cholesterol to make steroids such as estrogen, progesterone and testosterone. Your body also makes its own supply of vitamin D and uses cholesterol for that process. Cholesterol is a major component of bile -- a soap-like substance your liver makes to break down fats. Your body breaks down cholesterol in foods but you also make it in your liver.
Types of Cholesterol
Cholesterol is classified into two types: LDL and HDL. LDL cholesterol has the potential to clog your arteries. HDL cholesterol binds with the LDL cholesterol to carry it out of your blood stream and back to the liver where it is converted to bile. According to the American Heart Association, your total cholesterol should be below 200 mg/dL -- your LDL should be less than 129 mg/dL and your HDL should be above 50 mg/dL.
Phospholipids
Phospholipids are chains of fatty acids. Your body uses phospholipids to make cell membranes. Every part of your body is made of cells. The cell membranes serve two functions. They hold the cells together and they control what passes into and out of the cells. Your cells have a life cycle and are constantly dividing, growing and dying. Your body uses phospholipids to make the membranes of new cells and maintain the membranes of existing cells.
References
- "Principles of Anatomy and Physiology"; Gerard J. Tortora et al.; 2010
- Mayo Clinic: Cholesterol levels: What Numbers Should You Aim For?
- UC Clermont College Biology: Lipids
