Cholesterol is a waxy, fat-like substance found in your blood, according to the American Heart Association (AHA). It gets a bad rap, but your body actually needs cholesterol to function properly. The key, as with most things, is striking a healthy balance.
Too-high cholesterol levels are a major risk factor for coronary heart disease, heart attack and stroke. Knowing what's considered a dangerous total cholesterol level is the first step toward lowering your risk.
In order to understand high cholesterol, it can be helpful to know a bit more about the types of cholesterol and what they do.
Cholesterol can't dissolve in blood on its own. So the body packages it (along with fat) into tiny, protein-covered particles called lipoproteins, according to Harvard Health Publishing. This allows cholesterol to mix into the blood and travel throughout the body. Cholesterol is crucial for building cells. It's also important for making hormones (including estrogen and testosterone), vitamin D and substances needed for digestion.
There are two types of cholesterol you should know about: low-density lipoproteins (LDL) and high-density lipoproteins (HDL).
LDL cholesterol is often called "bad" cholesterol, per the AHA. If there is too much LDL in the body, it can join with other substances and create thick deposits in the arteries. These deposits — called plaque — can cause the arteries to become narrow and rigid, restricting the flow of oxygen-rich blood throughout the body. This condition is called atherosclerosis and can eventually lead to a heart attack or stroke.
HDL, on the other hand, helps prevent plaque build up. The Harvard T. H. Chan School of Public Health describes HDL cholesterol as tiny garbage trucks. It moves through the bloodstream and picks up excess LDL from the blood and arterial walls before returning it to the liver for disposal.
What Are Dangerous Cholesterol Levels?
Cholesterol levels are checked with a simple blood test and measured in milligrams per deciliter (mg/dL). According to the Mayo Clinic, total cholesterol is grouped into the following three categories:
- Less than 200 mg/dL is considered healthy
- Between 200 and 239 mg/dL is borderline high
- 240 mg/dL and higher is classified as high
But it may surprise you to learn that your total cholesterol number might not give you the full picture.
A person's level of non-HDL cholesterol is more of a concern than their total cholesterol level, says Robert Eckel, MD, professor of medicine, emeritus, at the University of Colorado, Anschutz Medical Campus, former president of the American Heart Association and president of the American Diabetes Association.
A non-HDL level is simply a person's total cholesterol minus their HDL cholesterol. "Non-HDL cholesterol is a very important predictor for the risk of heart disease, stroke or death from cardiovascular disease," Dr. Eckel tells LIVESTRONG.com.
A healthy level of non-HDL cholesterol is less than 130 mg/dL, according to the Mayo Clinic. If your test results are higher, you are at an increased risk of heart disease.
Doctors can also measure the ratio between HDL and LDL levels. Your HDL-to-LDL cholesterol ratio is simply your total cholesterol level divided by your HDL cholesterol. If your total cholesterol is 200 mg/dL and your HDL is 50 mg dL, for example, your HDL-to-LDL ratio is 4-to-1. A ratio greater than 4-to-1 (so, 5-to-1 or higher) is considered unhealthy, per the Mayo Clinic.
But according to Dr. Eckel, studies show that non-HDL is the best predictor of cardiovascular disease, better than total cholesterol or LDL-to-HDL ratios. Though many clinicians still use other tests, Dr. Eckel says non-HDL tests are increasingly common.
On its own, high cholesterol doesn't cause symptoms. A blood test is the only way to determine your cholesterol levels.
Reduce Your Risk
You may have heard that you should limit or avoid cholesterol-rich foods — particularly eggs — to reduce your risk of heart disease. But a February 2015 report by the USDA Dietary Guidelines Advisory Committee found that eating high-cholesterol foods (namely, animal products) had less of an impact on blood cholesterol levels than eating fatty foods and carbohydrates.
Though it appears that high blood cholesterol isn't caused directly by the cholesterol in food, many cholesterol-rich foods are also high in saturated fat. According to Dr. Eckel, eating a lot of saturated fats like meats, dairy and baked goods is linked to high cholesterol. Eggs are the exception — high in cholesterol but low in saturated fat.
Per the Mayo Clinic, lifestyle factors are the most common causes of high cholesterol. Besides poor diet, other factors include lack of exercise, obesity and cigarette smoking. High cholesterol can also be genetic or related to old age.
However, there is good news: Because high cholesterol is often associated with lifestyle habits, a healthy diet, staying active and quitting smoking can go a long way toward reducing your risk. In fact, the Mayo Clinic says exercise raises HDL cholesterol levels (the "good" cholesterol) and increases the size of LDL particles, making them less harmful.
Along with lifestyle changes, there are medications you can take to help lower your cholesterol. Discuss your options with your doctor.
Is This an Emergency?
- American Heart Association:"Control Your Cholesterol"
- Harvard T.H. Chan School of Public Health: "Cholesterol"
- Mayo Clinic: "High Cholesterol"
- Mayo Clinic: "Cholesterol Ratio or Non-HDL Cholesterol: Which Is Most Important?"
- USDA: "Scientific Report of the 2015 Dietary Guidelines Advisory Committee"
- Harvard Health Publishing: "How It's Made: Cholesterol Production in Your Body"