This information has been reviewed and adapted for use in South Carolina by J. G. Hunter, HGIC Information Specialist, and K. L. Cason, Professor, State EFNEP Coordinator, Clemson University. (New 09/05.)
Cholesterol is a waxy, fatlike substance that occurs naturally in every body cell and is needed by the body to function normally. It is found throughout the body, including the brain, nerves, muscle, hormones, vitamin D, and the bile acids that help to digest and absorb fat. With the help of sunlight, cholesterol in skin can change to vitamin D, which is essential for building strong bones.
Only a small amount of cholesterol is needed in the blood to meet all the body’s needs. Too much cholesterol in the bloodstream can lead to atherosclerosis, a type of "hardening of the arteries." Atherosclerosis is a condition in which cholesterol and fat are deposited in artery walls, causing them to become narrow and reducing blood flow. Narrowing of the coronary arteries by atherosclerosis can produce signs and symptoms of heart disease, including angina and heart attack. Sometimes there are no symptoms until an artery is about 75% blocked.
There are two types of cholesterol: blood (serum) and dietary cholesterol. Blood (serum) cholesterol circulates in the bloodstream. While every cell can make cholesterol, the liver produces most of it. When the body makes too much, this increases the risk for heart disease, including heart attack and stroke.
The body of an adult can make all the cholesterol it needs, but most people also get it from foods. Unlike adults, children under age two do not produce enough cholesterol; therefore, their food must supply part of it.
Plants do not produce cholesterol, even if they contain fat. Dietary cholesterol only comes from foods of animal origin. Common sources are eggs, meats, poultry, fish, dairy products and animal fats, such as butter or lard.
Blood cholesterol cannot mix with blood, so it needs a vehicle to transport it around the bloodstream. Therefore, cholesterol uses three lipoproteins as vehicles: high density lipoproteins (HDL), low density lipoproteins (LDL) and very low density lipoproteins (VLDL). These three measures make up total blood cholesterol level. Table 1 shows what LDL and HDL do in the body and their effects on risk of heart disease.
|Full Name:||Low Density Lipoprotein.||High Density Lipoprotein.|
|What it does:||Takes cholesterol from the liver to the rest of the body, depositing some on artery walls and vessels.||Primarily takes cholesterol from body tissue back to liver for removal from the body.|
|Effects on risk of heart disease:||Excess amounts increase risk.||High amounts reduce risk.|
|Nickname:||"Bad" cholesterol.||"Good" cholesterol.|
Triglycerides are the main form of fat in food, whether it is saturated, monounsaturated, or polyunsaturated. The body produces them when excess calories are eaten from any foods (protein, carbohydrate or fat). Most of the fat in the body is stored as triglycerides. Triglycerides trigger the liver to make more cholesterol, causing the levels of LDL and total cholesterol to rise. The desired level for triglycerides is < 250 mg/dL. High triglyceride levels alone may not be associated with heart disease. Triglyceride levels are affected by alcohol, medication, hormones, diet, recent exercise, menstrual cycle, and time of day.
The National Cholesterol Education Program (NCEP) recommends that everyone age 20 and older obtain a "fasting lipoprotein profile" every five years, more often for older adults and people at risk for heart disease. A child is considered at risk if a parent has a total cholesterol level of 240 mg/dL or higher or suffered a heart attack before age fifty-five, and if there is a family history of heart disease. A "fasting lipoprotein profile" is a blood test done after a nine to twelve-hour fast without food, liquids or pills. It reveals information about the total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride levels in the blood.
Total cholesterol is made up of HDL cholesterol (good) and LDL cholesterol (bad). Problems develop when the total cholesterol or LDL cholesterol gets too high and HDL is too low.
There should be more HDL cholesterol than LDL cholesterol. HDL carries the artery clogging cholesterol out of the body, while LDL carries the cholesterol around the body, depositing it where it can cause serious problems.
Results of the "fasting lipoprotein profile" can help determine the overall risk for heart disease. Other risk factors include: age, gender, family history, high-fat eating, inactivity, cigarette smoking, excessive alcohol intake, hypertension, diabetes, obesity and low HDL. Before menopause, women usually have lower cholesterol levels than men. However, women’s LDL cholesterol often rises after menopause.
Table 2 shows how test results are classified for everyone, regardless of height and weight. Since this test is a per unit measurement rather than a measure of all the cholesterol in the body, each deciliter of blood should contain less than 200 milligrams of cholesterol.
Some doctors also believe that the ratio of total cholesterol to HDL (TC/HDL) is the most predictive measure of risk for heart disease. Women should strive for a ratio less than 4.0 and men should strive for less than 4.5.
According to scientific evidence, blood cholesterol can be affected by the type and amount of dietary fat consumed. High cholesterol levels and high LDL levels are most often related to a diet high in saturated fats and a sedentary lifestyle. Dietary cholesterol can raise blood cholesterol but generally is not as important as saturated fat and total fat in the diet.
|Total Cholesterol||HDL Cholesterol|
|Desirable||< 200 mg/dL||Low||< 40 mg/dL|
|Borderline High||200 – 239 mg/dL||High1||> 60 mg/dL|
|High||> 240 mg/dL||1 An HDL of 60 mg/dL and above is considered protective against heart disease.|
|Optimal||< 100 mg/dL||Normal||< 150 mg/dL|
|Near Optimal/Above Optimal||100 – 129 mg/dL||Borderline High||150 –199 mg/dL|
|Borderline High||130 –159 mg/dL||High||200 – 499 mg/dL|
|High||160 – 189 mg/dL||Very High||> 500 mg/dL|
|Very High||> 190 mg/dL|
To lower blood cholesterol levels, eat less fat, especially saturated fats, and replace some saturated fats with polyunsaturated and monounsaturated fats (especially olive and canola oil). High total blood cholesterol levels and LDL cholesterol levels increase risk of heart disease while lower levels reduce risk. Higher levels of HDL cholesterol help lower the risk for heart disease.
Genetics can be an important factor as well. Some people have genetically high blood cholesterol levels, and despite their best efforts cannot lower their cholesterol into the safe range without the help of medication.
There is no single type of fat. Rather, the word "fat" is often used to refer to all of the fatty substances found both in food and in the body. Here are the types of fat.
Lipid: Scientific term referring to fat, cholesterol and other fat-like substances. A common quality among lipids is that they do not dissolve in water.
Lipoprotein: A protein-coated transporter that carries fat and/or cholesterol in the bloodstream.
Triglycerides: Scientific name for the main form of fat found in the diet and in the body. Most of the fat in the body is stored as triglycerides.
Saturated Fats: Usually solid or firm at room and refrigerator temperatures, saturated fats have all of the hydrogen atoms they can hold (saturated with hydrogen). They can raise blood cholesterol more than anything else in the diet. They trigger the liver to make more total and LDL cholesterol. Saturated fats primarily come from animal products, such as meat, butter, lard, cheese, whole milk, and cream. They are also found in tropical plant oils, such as coconut and palm, hydrogenated vegetable oil and cocoa butter (in chocolate.)
Monounsaturated Fats: Liquid at room temperature, monounsaturated fats are missing one pair of hydrogen atoms. They lower blood cholesterol and trigger more HDL cholesterol production. Monounsaturated fats primarily come from plants and include olive oil, canola oil and peanut oil.
Polyunsaturated Fats: Liquid at room temperature, polyunsaturated fats are missing two or more pairs of hydrogen atoms. They can lower total blood cholesterol and may lower HDL, as well as LDL. Many common vegetable oils, such as corn, soybean, safflower, sesame, cottonseed and sunflower oil, are high in polyunsaturated fats.
Hydrogenated Fats: Polyunsaturated fats and monounsaturated fats are sometimes processed to make them stable and solid at room temperature and to protect against rancidity. Examples are stick margarine and packaged crackers and cookies. Hydrogen atoms are added through a process called hydrogenation.
Trans Fatty Acids: A type of fat formed during the process of hydrogenation. Trans fatty acids act like saturated fats in the body and tend to raise blood cholesterol levels. They have been shown to increase LDL cholesterol and lower HDL cholesterol, which may increase the risk for heart disease.
Omega-3 Fatty Acids: A type of fatty acid that is highly polyunsaturated. Omega-3 fatty acids are mainly found in higher-fat, cold-water fish, such as salmon, albacore tuna, mackerel, whitefish and herring. While eating fish is encouraged, the use of fish oil supplements is not currently recommended by the American Heart Association. Additional omega-3 sources are nuts, soy, canola and flaxseed oils. Diets high in omega-3 fatty acids may help lower levels of LDL cholesterol and triglycerides and reduce risk of heart disease. They may protect from hardening of the arteries and help reduce blood clotting.
Omega-6 Fatty Acids: Polyunsaturated fatty acids found in vegetable oils. Soybean, corn and safflower oils are good sources. Omega-6s may reduce the risk of heart disease by lowering total and LDL cholesterol levels. However, they also may lower HDL levels.
Frequently, recommendations for fat are given in percentage of calories from fat or fat calories. The average American gets about 34 percent of total calories from fat. Most medical experts think this is too much. The U.S. Dietary Guidelines advise a general reduction in fat (especially saturated fat) and cholesterol. Table 3 presents the dietary recommendations for fat and cholesterol intakes for both the general public and for people with high LDL cholesterol, heart disease and/or diabetes. These recommendations are for the total diet, not a single food or meal.
|Nutrient||People without Heart Disease or High LDL Cholesterol||People with Heart Disease, Diabetes, or High LDL Cholesterol|
|*By the American Heart Association and the National Cholesterol Education Program
1A higher fat intake is allowed, provided most of it is unsaturated fat, and may be needed to prevent low HDL levels from worsening
|Total Calories||Balance energy intake and expenditure to maintain desirable body weight and prevent weight gain.|
|Total Fat||Less than 30% of total calories||25 – 35% of total calories|
|Saturated Fat||Less than 10% of total calories||Less than 7% of total calories|
|Polyunsaturated Fat||Up to 10% of total calories|
|Monounsaturated Fat||10-15% of total calories|
|Cholesterol||Less than 300 mg/day||Less than 200 mg/day|
Some people with high risk may find that diet therapy alone is inadequate. Most people, however, continue diet therapy at least six months before deciding whether to add drug treatment.
Optimal fat intake for children is unknown, according to the American Academy of Pediatrics. However, 30 percent of calories from fat seems sensible for adequate growth and development in children, especially after the age of two.
Diet impacts blood cholesterol levels both positively and negatively. Dietary cholesterol can elevate blood cholesterol levels, although it does not automatically become cholesterol in blood. The total amount of fat eaten, especially saturated fat, has a greater impact on blood cholesterol levels.Here are some simple daily guidelines for lowering blood cholesterol:
In Summary: Eat foods low in saturated fat and cholesterol, and eat lots of fruits, vegetables, whole grains and non-fat dairy products. Foods known to help lower blood cholesterol include soluble fiber, garlic, salmon, foods rich in vitamin C and E, and food products that contain plant stanols or plant sterols. Maintain a healthy weight and stay physically active.
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