Total cholesterol includes triglycerides, HDL and LDL. Triglycerides provide energy from fat. LDL and HDL are transport vehicles designed specifically to carry cholesterol to and from the cells. The amount of LDL and HDL in the blood indicates the proportion of cholesterol going out to the cells and coming back to the liver. LDL has health implications for the heart while HDL has a protective effect by reducing the amount of cholesterol in the blood.
Distinction
Although people may refer to LDL as "bad cholesterol," and HDL as "good cholesterol," there is only one type of cholesterol. The difference between the LDL and HDL transport vehicles is in the proportion of lipids and proteins carried within them and whether they are taking cholesterol to the cells or bringing it back for disposal, according to Eleanor Whitney and Sharon Rolfes in the book "Understanding Nutrition."
LDL
Low-density lipoproteins (LDL) carry cholesterol, triglycerides and phospholipids throughout the body so the cells can take what they need. Cholesterol becomes incorporated in cell membranes to strengthen them or help make hormones. Triglycerides provide energy. Phospholipids serve as emulsifiers, helping fat-soluble vitamins and hormones move in and out of the cells.
When more cholesterol is transported through the blood to the cells than they need, the excess may contribute to a buildup of plaque in arteries, including coronary arteries. The narrowing of coronary arteries increases blood pressure. A blood clot in a narrowed artery may even block the flow of blood, causing heart attack or stroke.
HDL
High-density lipoproteins (HDL). carry cholesterol and other lipids released by cells back to the liver for disposal or recycling. This helps take cholesterol out of circulation.
Recommended Levels
According to the National Heart, Lung and Blood Institute, an optimal level of LDL cholesterol is less than 100 mg per deciliter. Other readings include near optimal (100 to 129), borderline high (130 to 159), high (160 to 189) and very high (190 or above).
A low HDL reading is less than 40 mg per deciliter. High is 60 or above. An HDL number above 60 is called a "negative risk" factor because rather than indicating risk, it becomes a protective factor.
Improvement
To avoid confusion, remember HDL starts with the letter "H," as in healthy or high. Higher is better for HDL numbers because it is healthy. LDL starts with the letter "L" as in less healthy or low. Lower numbers are better for LDL because it is less healthy.
A doctor can order a fasting blood lipid profile test to measure HDL and LDL. To move HDL and LDL test results in the right direction and improve the HDL-to-LDL ratio, begin by maintaining a healthy body weight. Limit intake of saturated fat, total fat and dietary cholesterol. Increase consumption of foods that contain soluble fiber and antioxidants. Increase physical activity. If alcohol is consumed, keep the amount moderate.
References
- "Understanding Nutrition (Ninth Edition)"; Eleanor Noss Whitney and Sharon Rady Rolfes; 2002
- National Cholesterol Education Program: National Heart, Lung and Blood Institute--Cholesterol Guidelines
- "Krause's Food, Nutrition and Diet Therapy (10th Edition)"; L. Kathleen Mahan and Sylvia Escott-Stump; 2000.
