Dear Dr. Toshi,
When you go get your annual physical, your doctor may order a "lipid panel" as one of your blood tests. Lipids are fats and fatty substances in your body, and the results of the lipid panel include your total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides.
You might recall that in an earlier column I called LDL your bad cholesterol and HDL your good cholesterol. I'll talk more about those today. You may also wonder about the relationship between your lipid panel and the fats that you eat in your diet, like the trans-fat, saturated fat, monounsaturated fat, and polyunsaturated fat you read about last week. "Aren't they fats, too? Are they measured in the lipid panel, too?" These are things I'll talk about today.
So, what is cholesterol? Cholesterol is a waxy, fat-like substance found only in animals, including humans. Your liver makes most of the cholesterol in your body. We also eat food that contains cholesterol, such as meat including poultry, seafood, eggs, and dairy products, but there isn't any cholesterol in plants. Cholesterol is important for your body in many different ways. For example, it's an essential structural component of every cell in your body, it's used to make bile acids (which you need for your digestion) in your gall bladder, it's used to make certain hormones such as estrogen and testosterone, and your body also uses it to make vitamin D. The problem is that we often have too much cholesterol in our body, and that's bad for a number of reasons.
Cholesterol is carried in the blood by two carriers. One is called low-density lipoprotein (LDL), which carries cholesterol from the liver to different parts of the body. The other one is high-density lipoprotein (HDL), which carries excess cholesterol back to the liver to be disposed of. That's why HDL is called the good cholesterol. It's known that a high level of LDL (bad cholesterol) causes "plaque" to build up on the walls of our arteries, which makes them narrower and stiffer or harder. This plaque buildup is called "atherosclerosis," and these damaged arterial walls can cause blood clots to form, blocking blood flow, which can cause a heart attack or stroke. As a result, many people take a statin medication such as atorvastatin (Lipitor) or rosuvastatin (Crestor) to lower their LDL (bad cholesterol) and raise their HDL (good cholesterol).
Unfortunately, our bodies don't have a precise system to balance the good HDL cholesterol and bad LDL cholesterol, and as we get older the bad LDL cholesterol increases in our bodies. Also, some factors can make the bad LDL go even higher, such as an unhealthy diet, lack of physical activity, and obesity or being overweight. About four out of ten American adults have high cholesterol (that is, over 200 mg/dL), which might be fewer people than you thought, but remember that "adults" include young people in their twenties. It's known that cholesterol starts going up at very young age. It's also known that people with any body type can have high cholesterol, including both thin people and people who are overweight. A good level of the bad cholesterol, LDL, is less than 130. But this target depends on your medical condition, too. For example, if you have diabetes, your target is less than 100. If you've had a heart attack in the past, your target is less than 70. You want to have a high level of good cholesterol, HDL, and the best level is 60 or higher.
Finally, let's talk about triglycerides, which are also part of the lipid panel. This is where the different kind of "fats" that I talked about last week come in. Triglycerides is a scientific name for the main form of fat in our body and in our food. As the name, "tri-" indicates, triglycerides have three fatty acids (saturated fat, mono- or polyunsaturated fat) in different combinations. I also mentioned that trans-fats are so bad they're almost banned in the U.S., but triglycerides can actually contain trans-fatty acids. A high level of triglycerides that contain a lot of saturated fats and trans-fats in the blood triggers the liver to make more cholesterol, raising the level of LDL and the level of total cholesterol. This increases your risk of heart attacks, strokes, and other fatal medical conditions. The desirable level of triglyceride is less than 150.
That's why doctors are so concerned about your cholesterol levels. I hope this helped understand the lipid panel and the big impact it can have on your life!
Dr. Toshiko (Toshi) Luckow, MD is a Family Medicine physician at the West River Health Services hospital and clinics.