To many people, the word "cholesterol" has a bad connotation. Admittedly, excessive cholesterol levels in the blood can negatively affect your health. Yet this waxy substance is necessary to your body's normal function, notes scientist Pamela Champe. For, it serves as a key component of cell membranes, as well as a building block for steroid hormones, vitamin D and bile acids. The key is balance.
Negative Effects
Excess cholesterol can accumulate in your blood vessels, leading to a buildup of fatty deposits known as plaque, indicates FamilyDoctor.org. Depending on its size, this plaque may narrow or completely block the opening of your blood vessels. Cholesterol plaques may also break, resulting in blood clots. Both the intact plaque and clots can disrupt the blood supply to various organs, including the heart and brain.
Main Types
Because of its hydrophobic or "water-hating" nature, cholesterol does not travel in the blood in its free form. Rather, carrier molecules known as lipoproteins must transport it. For instance, low-density lipoprotein, or LDL, carries cholesterol from the liver to the rest of the body. In contrast, high-density lipoprotein, or HDL, removes cholesterol from your bloodstream and carries it back to the liver for disposal. Thus, the term "bad cholesterol" usually refers to LDL, while HDL is considered "good."
Total Cholesterol
A total cholesterol test measures the cholesterol in your blood in milligrams per deciliter of blood, or mg/dL, or in millimoles per liter of blood, or mmol/L. According to Quest Diagnostics, this total cholesterol count includes HDL, LDL and VLDL levels. Even though VLDL, or very low-density lipoproteins, mainly carry blood fats known as triglycerides, they can also increase cholesterol buildup in your blood vessels.
Total Values
Ideally, an adult should have a total cholesterol level lower than 200mg/dL or 5.17mmol/L, indicate the American Heart Association guidelines. Values ranging from 200mg/dL to 239mg/dL, or 5.17mmol/L to 6.18mmol/L, are considered borderline high. The term "high cholesterol" usually refers to a total cholesterol count of 240mg/dL, or 6.21mmol/L, or higher.
Partial Values
In addition to total cholesterol count, the American Heart Association considers HDL and LDL cholesterol levels as important markers of heart disease and stroke risk. For instance, HDL values below 40mg/dL for men and 50mg/dL for women, as well as LDL levels exceeding 159mg/dL, reportedly increase heart disease and stroke risk. In contrast, HDL levels above 60mg/dL have protective effects on the heart.
Considerations
According to the American Heart Association, a high cholesterol level more than doubles your risk of coronary heart disease compared to someone whose total cholesterol is lower than 200mg/dL. Note, however, that knowing the proportions of your HDL and LDL becomes particularly important when your total cholesterol count is elevated. For if your elevated total cholesterol count mostly comes from a high LDL level, your risk of heart disease or stroke may increase. Conversely, if an elevated HDL level accounts for most of your total cholesterol, you may not be at higher risk.
References
- American Heart Association: Cholesterol Levels
- Family Doctor: Cholesterol Overview
- "Lippincott's Illustrated Reviews: Biochemistry"; Pamela Champe, Ph.D., et al.; 2006
- Quest Diagnostics: Cholesterol and Triglycerides Test
