by Julia Blank, MD
Cholesterol is a fat-like substance that has many roles in the body. It forms an essential component of all of the body’s cell membranes, and is a building block of various hormones such as testosterone and estrogen. It also circulates in the bloodstream, “piggy-backing” on proteins called lipoproteins. These complexes are categorized according to size and density, which in turn determines whether the effect on the body is beneficial or harmful. For example, low-density-lipoprotein (aka LDL, or “bad cholesterol”) can accumulate along the inner walls of arteries, forming artery-clogging “plaques” that increase your risk of having a heart attack or stroke. High-density-lipoprotein (HDL, or “good cholesterol”), on the other hand, scavenges for cholesterol to take out of circulation and return to the liver, thereby reducing your risk of heart attack or stroke.
Cholesterol comes from two sources. Foods such as eggs, butter, and red meat contain both cholesterol and saturated fat, which is converted by the body into cholesterol. We also make cholesterol de novo in the liver—in fact, the liver produces all the cholesterol that we need.
When you get your cholesterol checked at the doctor’s office, you usually get a “lipid profile” drawn that includes total cholesterol, LDL, HDL, and triglycerides. Triglycerides are a form of fat stored in the body’s fat cells; triglycerides also circulate in the blood. High levels can come from a high carbohydrate intake (especially simple sugars, like those found in sweets, soda, and white bread/rice products), or as a result of other conditions such as diabetes. Like people who have high LDL, those with elevated triglycerides can be at higher risk for cardiovascular disease.
Cholesterol and Your Health: the Big Picture
High cholesterol—or, more precisely, high LDL—is a risk factor for cardiovascular disease. The higher the LDL and the lower the HDL, the greater the chance of having a heart attack or stroke.