Cholesterol, high

Definition

High cholesterol (hypercholesterolemia or hyperlipidemia) refers to the presence of higher than normal amounts of total cholesterol circulating in the bloodstream. Cholesterol is a fatty substance (lipid) that is essential to the body as protection for the walls of the vasculature (veins and arteries) and linings of body organs, a component in the manufacture of hormones, and a factor in the digestion of consumed fats in foods. It is manufactured in the liver and carried throughout the body in the bloodstream. Cholesterol is also a component of animal tissue and can be consumed in products such as meat, eggs, fish, milk, and milk products such as butter and cheese. Elevated cholesterol levels can result in the accumulation of fatty deposits on blood vessel walls, narrowing veins and arteries and impeding blood flow to the heart, brain, and other organs.

Description

Cholesterol has both a good form and a bad form that add up to total cholesterol when measured together. The body needs cholesterol to produce bile acids that help digest fats ingested in food, make hormones, protect cell walls, and participate in other processes that help maintain health. Ironically, cholesterol can also be a problem, if too much is manufactured by the liver or consumed through the diet and not metabolized or used. The utilization of fat in the body, or fat metabolism, is a complex process, complicated even more by abnormally high levels of cholesterol found circulating in the blood. Although high cholesterol is not often found in young children, it may begin to develop in adolescents or young adults either as an inherited condition or through unhealthy eating habits and can continue into adulthood, creating potentially serious health problems. High cholesterol levels and fatty deposits in veins and arteries (atherosclerosis) have been found during autopsies of children who have died of accidents and other causes.

The liver metabolizes cholesterol, including the cholesterol obtained from foods in the diet. The components of cholesterol are then carried into the bloodstream bound to the surface of certain lipoproteins. Low-density lipoproteins or LDLs carry about 75 percent of the cholesterol into the blood and high-density lipoproteins carry the other 25 percent. LDL is the lipoprotein known as bad cholesterol because it consists primarily of cholesterol and is most associated with the development of vascular disease. Cholesterol is not the major part of HDL, the so-called good cholesterol, and the presence of higher amounts of HDL in the blood actually helps reduce the more harmful LDL levels. Another lipoprotein, very low-density lipoprotein (VLDL), carries harmful fats known as triglycerides but does not carry a significant amount of cholesterol. Triglycerides are also measured as part of a lipid profile and high levels are associated with vascular disease and heart disease. Cholesterol levels in blood serum vary considerably from day to day and even from one time of a day to another related to the consumption of fats in the diet.

High LDL (low-density lipoprotein) is a major precursor of vascular disease and heart disease. This form of cholesterol combines with triglycerides, cellular waste, calcium, and scar tissue to form a waxy deposit (plaque) on the inner walls of large and medium-sized arteries, causing a condition called hardening of the arteries (atherosclerosis or arteriosclerosis). Plaque typically builds up as people get older, more in some people than others depending on lifestyle (diet, exercise , alcohol consumption, and smoking ) and heredity. The result may be a narrowing (stenosis) or blockage of blood vessels, interrupting the essential flow of blood and oxygen to the heart, brain, abdominal organs, and peripheral circulation to the arms and legs. Eventually this can lead to heart attack or stroke , permanent damage to the heart or brain, and life-threatening complications.

The population as a whole is at some risk of developing high LDL cholesterol. Specific risk factors include a family history of high cholesterol, obesity , coronary artery disease (atherosclerosis), stroke, alcoholism , diabetes, high blood pressure, and lack of regular exercise. The chances of developing high cholesterol increase after the age of 45. One of the primary causes of high LDL cholesterol is a combination of too much fat and sugar in the diet, especially through the consumption of fast foods and refined or packaged foods, a problem that has been especially true in the United States since the advent of manufactured foods. A renewed interest in whole foods may help to alter the prevalence of high cholesterol and vascular disease.

An increased serum cholesterol may be found in familial hyperlipidemia or hypercholesterolemia, underactive thyroid ( hypothyroidism ), untreated diabetes, a high-fat diet, pregnancy, heart attack, stress, and certain liver conditions (cirrhosis). A decreased level may be found in liver dysfunction, overactive thyroid ( hyperthyroidism ), malabsorption, malnutrition , or advanced cancer , among other conditions.

Although high cholesterol has been shown to be a risk factor for developing atherosclerosis in adults, with associated increased morbidity and mortality, studies have not indicated that high cholesterol in children and adolescents is related to the development of specific illness or increasing mortality in adulthood. There is strong evidence in numerous research studies, however, that a family history of high cholesterol, atherosclerosis, heart attack, or stroke increases the risk of a child developing high cholesterol levels.

High cholesterol is often diagnosed and treated by general practitioners or family practice physicians. In some cases, the condition is treated by an endocrinologist or cardiologist. Pediatricians will generally refer affected children to the appropriate specialist.

Demographics

The U.S. Food and Drug Administration (FDA) estimates that 90 million American adults, roughly half the adult population, have elevated cholesterol levels. This estimate does not indicate that as many children are candidates for high cholesterol levels; however, about 2 percent of the U.S. population has a family history of hypercholesterolemia in parents or grandparents, and this history is the most common predictor of high cholesterol levels in children and adolescents. Before puberty , average total and LDL cholesterol levels are higher in girls than in boys. Both LDL and HDL levels are higher in non-Hispanic black children than in non-Hispanic whites and Mexican-American children.

Causes and symptoms

The causes of high cholesterol may be genetic or hereditary factors in the manufacture of cholesterol by the liver or in fat metabolism, a diet high in saturated fats and trans-fatty acids, obesity, alcoholism, smoking, and lack of exercise.

There are no readily apparent symptoms that indicate high cholesterol, high LDL, high triglycerides, or low HDL. Obesity is a general indication of possible high cholesterol levels. Labored breathing or general feelings of sluggishness and lack of energy may warrant examination by a physician and testing of cholesterol. Families or individuals who regularly consume a high-fat diet consisting of animal products, fast foods, and refined foods may also benefit from being tested for abnormal cholesterol levels.

When to call the doctor

Excess weight may be the only sign of possible high cholesterol in children. It is wise for parents to consult a physician if a child is consistently overweight and diet or exercise does not seem to make a significant difference. Sluggishness may also be noted if a child's veins and arteries are consistently filled with higher than normal amounts of fatty substances that are not being metabolized by the body.

Diagnosis

Total serum cholesterol is the cholesterol most often measured and reported in medical office tests, home tests, and blood cholesterol screening clinics; people who quote their cholesterol level as high may be talking about a total cholesterol of over 200mg/dL. A definitive diagnosis of high cholesterol, however, ideally includes measuring LDL, HDL, total cholesterol, and triglyceride levels, as well as the cholesterol to HDL ratio. This combination of tests performed in the clinical laboratory is called a lipid panel or lipid profile. Most physicians want to know the results of a lipid panel before diagnosing high cholesterol and recommending treatment. Screening for lipid levels in all children is not usually recommended. It is recommended that children whose parents have a total cholesterol level over 200mg/dL or whose family history includes heart disease or stroke in either parents or grandparents have a cholesterol screening performed. If the fasting blood level of cholesterol is 170 to 199 mg/dL, total cholesterol should be repeated and the two tests averaged. A final result of 200 mg/dL or over indicates that the entire lipid panel should be done to determine if hyperlipidemia is present.

In most adults the recommended levels for cholesterol and triglycerides, measured as milligrams per deciliter (mg/dL) of blood, are: total cholesterol, less than 200; LDL, less than 130; HDL, more than 35; triglycerides, 30–200; and cholesterol to HDL ratio, four to one. However, the recommended cholesterol levels may vary from person to person, depending on other risk factors such as a family history of heart disease or stroke or the presence of hypertension , diabetes, advanced age, alcoholism, or smoking.

The physician may recommend nuclear magnetic resonance (NMR) lipoprofile testing for individuals whose lipid measurements, history, and risk factors are not diagnostic, that is they are not revealing why an individual has coronary artery disease. Doctors have always been puzzled by why some people develop heart disease while others with identical HDL and LDL levels do not. Research studies in the early 2000s indicate that it may be due to the size of the cholesterol particles in the bloodstream. Nuclear magnetic resonance (NMR) lipoprofile exposes a blood sample to a magnetic field to determine the size of the cholesterol particles. Particle size also can be determined by a centrifugation test, in which blood samples are spun very quickly to allow particles to separate and move at different distances. The smaller the particles, the greater the chance of developing heart disease. It allows physicians to treat patients who have normal or close to normal results from a lipid panel but abnormal particle size.

Treatment

The primary goal of cholesterol treatment is to lower LDL to under 160 mg/dL in people without heart disease and who are at lower risk of developing it. The goal in people with higher risk factors for heart disease is less than 130 mg/dL. In patients who already have heart disease, the goal is under 100 mg/dL, according to FDA guidelines. Also, since low HDL levels increase the risk of developing heart disease, the goal for all individuals is to maintain an HDL of more than 35 mg/dL. These values apply to children and adolescents as well as adults.

First-line treatment of high cholesterol for all ages includes diet, exercise, and weight loss. The National Cholesterol Education Program recommends that children over age two eat a variety of foods for healthy development and ideal weight, consuming no more than 30 percent total fat in the diet and no more than 10 percent saturated fat as in animal foods. The American Heart Association Step 2 diet has been tested as a dietalone treatment and in conjunction with drug therapy for children with high cholesterol, with good results. Regular exercise through aerobic activity is recommended.

In addition to diet and exercise, a variety of prescription medicines are available to help reduce cholesterol levels in the blood; these medications may not always be recommended for children, except for those whose parents or grandparents have high cholesterol and coronary artery disease. A class of drugs called statins is known to help lower LDL in combination with dietary changes and exercise, and studies have shown that they have no adverse effects in children. A class of drugs called fibric acid derivatives is sometimes recommended to lower triglycerides and raise HDL. Doctors decide which drug is most effective for an individual based on the cause and the severity of the cholesterol problem and other health conditions that may be present, as well as possible side effects of the drug. Diet and exercise remain important factors in reducing elevated cholesterol levels, even if drug therapy is prescribed.

Alternative treatment

Alternative treatment of high cholesterol may include high doses of garlic, niacin, soy protein, algae, or other fatty acids, and the Chinese medicine supplement Cholestin (a red yeast fermented with rice).

GARLIC A number of clinical studies have indicated that garlic can offer modest reductions in cholesterol. A 1997 study by nutrition researchers at Pennsylvania State University found that men who took garlic capsules for five months reduced their total cholesterol by 7 percent and LDL by 12 percent. Another study showed that seven cloves of fresh garlic a day significantly reduced LDL, as did a daily dose of four garlic extract pills.

CHOLESTIN Cholestin has been available since 1997 as a cholesterol-lowering dietary supplement. It is a processed form of red yeast fermented with rice, a traditional herbal remedy used for centuries in China. Two studies released in 1998 showed Cholestin lowered LDL cholesterol by 20 to 30 percent. It also appeared to raise HDL and lower triglyceride levels. Although the supplement contains hundreds of compounds, the major active LDL-lowering ingredient is lovastatin, a chemical also found in the prescription drug Mevacor. The product is available as a dietary supplement, not a drug; its actual mechanism is not known. No serious side effects have been reported, but minor side effects, including bloating and heartburn, have been noted.

OTHER TREATMENT A study released in 1999 indicated that blue-green algae contains polyunsaturated fatty acids that lower cholesterol. The algae, known as Aphanizomenon flos-aquae (AFA) is available as an over-the-counter dietary supplement. Flax seed oil is another source of fatty acids known to reduce cholesterol levels. Niacin, also known as nicotinic acid or vitamin B3, has been shown to reduce LDL levels by 10 to 20 percent and raise HDL levels by 15 to 35 percent. It also reduces triglycerides. Because an extremely high dose of niacin is needed to treat cholesterol problems, it should only be taken under a doctor's supervision to monitor possible toxic side effects. Niacin can also cause flushing when taken in high doses. Soy protein with high levels of isoflavones also has been shown to reduce LDL levels by up to 10 percent. In 2003, a Cuban research study revealed that policosanol, a substance made from sugar cane wax or beeswax, lowered LDL cholesterol nearly 27 percent in study subjects.

Nutritional concerns

Several specific diet options have been shown to be beneficial for reducing cholesterol. A vegetarian diet provides up to 100 percent more fiber and up to 50 percent less cholesterol from food than a meat-based diet. A balanced vegetarian diet consists of at least six servings of whole grain foods, three or more servings of green leafy vegetables, two to four servings of fruit, two to four servings of legumes (protein source), and one or two servings of non-fat dairy products daily. The macrobiotic diet is similar, with brown rice being a staple, but with the addition of other protein sources such as fish and fowl, tofu, and other soy products (miso, tempeh). The low glycemic or diabetic diet is known to raise the HDL (good cholesterol) level by as much as 20 percent in three weeks. Low glycemic foods promote a slow but steady rise in blood glucose levels following a meal, which increases the level of HDL. They also lower total cholesterol and triglycerides. Low glycemic foods include certain fruits, vegetables, beans, and whole grains. Processed (packaged foods) and refined foods (white flour products, white rice) and refined sugars (white sugar, brown sugar, molasses, and products made with them) should be avoided in all diets. Soy protein can be added to the daily diet to help replace animal sources of protein and reduce cholesterol; a diet containing 62 mg of isoflavones in soy protein is recommended and can be incorporated into other diet regimens, including vegetarian, macrobiotic, and low glycemic.

Prognosis

High cholesterol is one of the key risk factors for heart disease and has been shown to be treatable. Left untreated, high levels of LDL and total cholesterol can lead to the formation of plaque, the narrowing of blood vessels, vascular disease, and subsequent heart attacks and stroke.

Prevention

Since a large number of people with high cholesterol are overweight, a healthy diet and regular exercise are probably the most beneficial ways to control cholesterol levels. Exercise is an extremely important part of burning calories obtained by eating fats and helps maintain lower bad cholesterol and higher levels of good cholesterol. Exercise should consist of 20 to 30 minutes of vigorous aerobic exercise at least three times a week. Exercises that cause the heart to beat faster include fast walking, bicycling, jogging, roller skating, swimming, and walking up stairs.

Nutritional concerns

In general, the nutritional goals for preventing high levels of cholesterol are to substantially reduce or eliminate foods high in animal fat, including meat, shellfish, eggs, and dairy products. The use of polyunsaturated fats in cooking is also recommended, including cold pressed oils such as olive oil, canola oil, and sesame oil. Many vegetable oils are hydrogenated or extracted at high temperatures and are best avoided. Trans-fatty acids found in solid shortenings, most margarines, and hydrogenated oils or products containing them should also be avoided because they are known to increase levels of LDL.

Parental concerns

Parents need not be concerned about high cholesterol levels in their children unless the child is obese or there is a family history of high cholesterol, heart attack, or stroke. Parents who have cholesterol levels over 200 mg/dL themselves may want to have their children's cholesterol levels tested. Much information is available from public health sources and family physicians about diet and exercise recommendations to help people of all ages reduce the risk of vascular disease and related illnesses, such as heart disease and stroke.

Resources

BOOKS

Bratman, Steven, and David Kroll. Natural Pharmacist: Natural Treatments for High Cholesterol. Roseville, CA: Prima Publishing, 2000.

PERIODICALS

"Eating a Vegetarian Diet that Includes Cholesterol-lowering Foods May Lower Lipid Levels as Much as Some Medications." Environmental Nutrition (March 2003): 8.

Sage, Katie. "Cut Cholesterol with Policosanol: This Supplement Worked Better than a Low-fat Diet in One Study." Natural Health (March 2003): 32.

ORGANIZATIONS

National Cholesterol Education Program. NHLBI Information Center, PO Box 30105, Bethesda, MD 20824–0105. Web site: http://www.nhlbi.nih.gov.

WEB SITES

"Cholesterol." MedlinePlus . Available online at http://www.nlm.nih.gov/medlineplus/cholesterol.html (accessed December 8, 2004).

L. Lee Culvert Ken R. Wells Teresa G. Odle