Hyperlipidemia
Hyperlipidemia, also known as hyperlipoproteinemia or dyslipidemia, is an elevation of lipid levels (fats) in the bloodstream. These lipids include cholesterol, cholesterol compounds, phospholipids and triglycerides, all carried in the blood as part of large molecules called lipoproteins.
Hyperlipidemia affects the way lipids are produced, used, carried in the blood, or disposed of by the body. There are three types of hyperlipidemias:
- Hyperlipoproteinemia: elevated levels of lipoproteins in the blood;
- Hypercholesterolemia: high cholesterol levels in the blood;
(Illustration by GGS Information Services/Thomson Gale.).
- Hypertriglyceridemia: high triglyceride levels in the blood.
It has been shown that people with a hyperlipidemia disorder are more likely to develop heart disease. For example, the normal body makes enough cholesterol for its needs. But when there is too much cholesterol, it accumulates in arteries, which can lead to their narrowing (atherosclerosis) and to heart disease or stroke.
The lipoproteins present in blood plasma that transport lipids belong to the following major groups:
- Very high-density lipoprotein (VHDL). VHDL consists of proteins and a high concentration of free fatty acids.
- High-density lipoprotein (HDL). HDL helps remove fat from the body by binding with it in the bloodstream and carrying it back to the liver for excretion in the bile and disposal. A high level of HDL may lower chances of developing heart disease or stroke.
- Intermediate-density lipoprotein (IDL). IDLs are formed during the degradation of very-low-density lipoproteins; some are cleared rapidly into the liver and some are broken down to low-density lipoproteins.
- Low–density lipoproteins (LDL). LDL transports cholesterol to extrahepatic tissues (outside the liver) to other parts of the body. A high LDL level may increase chances of developing heart disease.
- Very low–density lipoprotein (VLDL). VLDLs carry triglycerides from the intestine and liver to fatty (adipose) and muscle tissues; they contain primarily triglycerides. A high VLDL level can cause the buildup of cholesterol in arteries and increase the risk of heart disease and stroke.
- Chylomicrons. Proteins that transport cholesterol and triglycerides from the small intestine to tissues after meals.
Generally speaking, LDL levels should be low, and HDL levels high. This is why HDL is often called the ‘good cholesterol’ and LDL the ‘bad cholesterol’.
Hyperlipidemia by itself does not cause symptoms, so people are generally not aware that their lipid levels are too high.
Simple blood tests are done to check blood lipid levels. The National Cholesterol Education Program recommends that people be tested every 5 years after age 20. A lipoprotein test, also called a fasting lipid test, is commonly performed as part of a routine medical examination. The test measures lipid levels and usually reports on four groups:
- Total cholesterol (normal: 100-199 mg/dL)
- LDL (normal: less than 100 mg/dL)
- HDL (normal: 40-59 mg/dL)
- Triglycerides (normal: less than 150 mg/dL)
A total cholesterol value greater than 200 mg/dL is indicative of a greater risk for heart disease. However, LDL levels are a better predictor of heart disease, and they determine how your high cholesterol should be treated.
Treatment depends on lipid levels, the presence of risk factors for heart disease, and general health. When lipid levels are not balanced, the goal is to bring them under control and this is done with changing dietary habits. Hyperlipidemia is accordingly first treated by modifying eating habits:
- Reducing saturated fat intake to 7% of the daily intake of calories
- Reducing total fat intake to 25-35% of the daily intake of calories
- Limiting the dietary cholesterol to less than 200 mg per day
- Ensuring the intake of 20-30 g a day of soluble fiber.
- Ensuring the intake of plant sterols to 2-3 g daily
If dietary changes do not correct the hyperlipidemia, a course of drug therapy may be indicated. In the Unites States, men older than age 35 and post-meno-pausal women are generally candidates for lipid-low-ering medications.
To treat hyperlipidemia, a diet low in total fat, saturated fat, and cholesterol is recommended, along with reducing or avoiding alcohol intake. The American Heart Association (AHA) endorses the following dietary recommendations for people with high blood cholesterol:
- Total fat: 25% of total calories
- Saturated fat: less than 7% total calories
- Polyunsaturated fat: up to 10% total calories
- Monounsaturated fat: up to 20% total calories
- Carbohydrates: 50-60% total calories
- Protein: ~15% total calories
- Cholesterol: less than 200 mg/dL
- Plant sterols: 2 g
- Soluble fiber such as psyllium: 10- 25g
Categories of appropriate foods include:
- Lean meat/fish: less than 5 oz/day
- Eggs: less than 2 yolks per week (whites unlimited)
- Low fat dairy products (<1% fat): 2-3 servings/day
- Grains, especially whole grains: 6-8 tsp/day
- Vegetables: less than 6 servings per day
- Fruits: 2-5 servings per day
These recommendations translate into the following practical dietary guidelines:
- Select only the leanest meats, poultry, fish and shellfish. Choose chicken and turkey without skin or remove skin before eating. Some fish, like cod, have less saturated fat than either chicken or meat.
- Limit goose and duck. They are high in saturated fat, even with the skin removed.
- Some chicken and turkey hot dogs are lower in saturated fat and total fat than pork and beef hot dogs. There are also lean beef hot dogs and vegetarian (tofu) franks that are low in fat and saturated fat.
- Dry peas, beans and tofu can be used as meat substitutes that are low in saturated fat and cholesterol. Dry peas and beans also have a lot of fiber, which can help to lower blood cholesterol.
- Egg yolks are high in dietary cholesterol. A yolk contains about 213 mg. They should be limited to no more than 2 per week, including the egg yolks in baked goods and processed foods. Egg whites have no cholesterol, and can be substituted for whole eggs in recipes.
- Like high fat meats, regular dairy foods that contain fat, such as whole milk, cheese, and ice cream, are also high in saturated fat and cholesterol. However, dairy products are an important source of nutrients and the diet should include 2 to 3 servings per day of low-fat or nonfat dairy products.
- When shopping for hard cheeses, select them fat-free, reduced fat, or part skim.
- Select frozen desserts that are lower in saturated fat, such as ice milk, low-fat frozen yogurt, low-fat frozen dairy desserts, sorbets, and popsicles.
- Saturated fats should be replaced with unsaturated fats. Select liquid vegetable oils that are high in unsaturated fats, such as canola, corn, olive, peanut, saf-flower, sesame, soybean, and sunflower oils.
- Limit butter, lard, and solid shortenings. They are high in saturated fat and cholesterol.
- Select light or nonfat mayonnaise and salad dressings.
- Fruits and vegetables are very low in saturated fat and total fat, and have no cholesterol. Fruits and vegetables should be eaten as snacks, desserts, salads, side dishes, and main dishes.
- Breads, cereals, rice, pasta, grains, dry beans, and peas are high in starch and fiber and low in saturated fat and calories. They also have no dietary cholesterol, except for some bakery breads and sweet bread products made with high fat, high cholesterol milk, butter and eggs.
- Select whole grain breads and rolls whenever possible. They have more fiber than white breads.
- Most dry cereals are low in fat. Limit high-fat granola, muesli, and cereal products made with coconut oil and nuts, which increases the saturated fat content.
- Limit sweet baked goods that are made with saturated fat from butter, eggs, and whole milk such as croissants, pastries, muffins, biscuits, butter rolls, and doughnuts.
- Snacks such as cheese crackers, and some chips are often high in saturated fat and cholesterol. Select rather low-fat ones such as bagels, bread sticks, cereals without added sugar, frozen grapes or banana slices, dried fruit, non-oil baked tortilla chips, popcorn or pretzels.
Generally, drug therapy is considered when:
- the LDL cholesterol is 190 mg/dL or higher.
- the LDL cholesterol is 160 mg/dL or higher and there is one risk factor for heart disease.
- the LDL cholesterol is 130 mg/dL or higher and there are two risk factors for heart disease or diabetes.
- the LDL cholesterol is 100 mg/dL or higher and there is heart disease.
- the LDL cholesterol is greater than 70 mg/dL and there is recent heart disease along with diabetes, smoking, high blood pressure, or high triglycerides, low HDL, and obesity.
There are several types of drugs available to help lower blood cholesterol levels, and they work in different ways. Some are better at lowering LDL cholesterol, some are good at lowering triglycerides, while others help raise HDL cholesterol. Lipid-lowering medications include:
- Statin drugs, such as lovastatin, that prevent the liver from manufacturing cholesterol;
- Bile acid resins, such as cholestyramine and colestipol, that prevent the body from reabsorbing the cholesterol present in bile;
- Fibrates, such as bezafibrate, fenofibrate, or gemfibrozil, particularly effective in treating high triglyceride levels;
- Niacin (vitamin B5)
Prognosis depends on the presence any additional risk factors for heart disease, such as diabetes, high blood pressure, being male and over age 45 or female and over age 55, having a first-degree female relative diagnosed with heart disease before age 65, or a first-degree male relative diagnosed before age 55 and obesity. Outcome is also highly related to early diagnosis and treatment and compliance with therapy.
BOOKS
American Heart Association. American Heart Association Low–Fat, Low–Cholesterol Cookbook, 3rd Edition: Delicious Recipes to Help Lower Your Cholesterol. New York, NY: Clarkson Potter, 2005.
Durrington, P. N. Hyperlipidemia (Fast Facts). Albuquerque, NM: Health Press, 2005.
Freeman, M. W., Junge, C. E. Harvard Medical School Guide to Lowering Your Cholesterol. New York, NY: McGraw–Hill, 2005.
ICON Health Publications. Hyperlipidemia — A Medical Dictionary, Bibliography, and Annotated Research Guide to Internet References. San Diego, CA: ICON Health Publications, 2004. .
Kowalski, R. E. The New 8–Week Cholesterol Cure: The Ultimate Program for Preventing Heart Disease. New York, NY: Collins, 2002.
Lipski, E. Digestive Wellness. New York, NY: McGraw– Hill, 2004.
McGowan, M. P. 50 Ways to Lower Cholesterol. New York, NY: McGraw–Hill, 2002.
ORGANIZATIONS
American Heart Association (AHA). 7272 Greenville Avenue, Dallas, TX 75231. 1-800-242-8721. <www.americanheart.org>.
Center for Disease Control (CDC). Division for Heart Disease and Stroke Prevention, 4770 Buford Hwy NE, Atlanta, GA 30341-3717. 770-488-2424. <www.cdc.gov/cholesterol/faqs.htm>.
National Heart Lung and Blood Institute (NHLBI). P.O. Box 30105, Bethesda, MD 20824-0105. 301-592-8573. <www.nhlbi.nih.gov>.
Monique Laberge, Ph.D.
