Lipids are fatty substances in the blood, and include cholesterol and triglycerides. All lipids play important roles throughout the body, but abnormal levels in the blood can cause problems. High levels of lipids may be caused by one or a combination of:

• Genetics
• Diet that has excess calories, usually higher in carbohydrates and fat
• Obesity
• Sedentary lifestyle

High levels of lipids in the blood can contribute to a buildup of plaque in the inside walls of the blood vessels. This build up causes a thickening and hardening of the blood vessel walls known as atherosclerosis. The damaged blood vessels make it difficult for blood to flow freely and in some cases can cause a blockage of blood flow. If the blockage occurs in the heart or brain it can lead to a heart attack or stroke.

Two types of lipids are cholesterol and triglycerides.

Cholesterol

Cholesterol is a waxy substance that is used to build cells and hormones. Most of your cholesterol is made inside the body, but some comes from the foods we eat such as dairy products, meat, and fish.

There are two main types of cholesterol:

• High-density lipoprotein (HDL) cholesterol —Often called the “good” cholesterol because it helps to protect against heart disease. HDL may carry other types of cholesterol away from arteries and to the liver. Higher levels of this cholesterol are ideal.
• Low-density lipoprotein (LDL) cholesterol —This is often referred to as the “bad” cholesterol because it is more likely to stick to the walls of your blood vessels. High LDL cholesterol levels increases the risk of heart disease.

Abnormal cholesterol levels are sometimes caused by genetic conditions or medications that lead to low HDL or high LDL levels. However, cholesterol problems can also come from a combination of dietary choices and low levels of physical activity.

Triglycerides

Triglycerides are a type of fat that your body can store away and use for energy when needed. They are made from unused or extra calories that we eat. Triglycerides move throughout the body in the blood. High levels of this fat in the blood can contribute to a plaque build up in blood vessels.

High triglycerides can be caused by a high calorie diet, especially one high in carbohydrates but is also often associated with other conditions such as:

• Diabetes
• Obesity—especially with high amount of fat around the stomach
• Metabolic syndrome
• Hypothyroidism
• Genetic condition

American College of Cardiology/American Heart Association. 2013 ACC/AHA Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults. J Am Coll Cardiol. 2013: early online. Available at:
http://circ.ahajournals.org/content/early/2013/11/11/01.cir.0000437738.63853.7a.full.pdf
Accessed January 9, 2014.

Hypercholesterolemia. EBSCO DynaMed website. Available at: EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed
Updated November 20, 2013. Accessed January 9, 2014.

Hypertriglyceridemia. EBSCO DynaMed website. Available at: EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed
Updated November 20, 2013. Accessed January 9, 2014.

What is cholesterol? National Heart, Lung, and Blood Institute website. Available at:
http://www.nhlbi.nih.gov/health/health-topics/topics/hbc
Updated September 19, 2012. Accessed January 9, 2014.