People obtain cholesterol through its production by the liver and also via their diet. Total blood cholesterol is a measure of low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol. Another type of fat in the blood, triglycerides, are also considered a component of cholesterol. Blood cholesterol is measured in milligrams per deciliter (mg/dL). High cholesterol levels can lead to coronary artery disease.
Lipoproteins
Blood is composed primarily of water, such that cholesterol and triglycerides must be carried through the bloodstream by protein packages. These proteins are known as apoproteins, and the combination of lipids (fats) and apoproteins is called lipoprotein.
LDL Cholesterol
LDL cholesterol is the so-called bad cholesterol. Although cholesterol is essential for cell health, LDL levels can become too high. Cholesterol then may accumulate in the arteries and form plaque, a hard deposit that narrows the arteries. If a blood clot forms and blocks a constricted artery, the person may have a stroke or heart attack. LDL levels should be less than 130 mg/dL. A level of 160 or higher is considered high risk.
High levels of LDL cholesterol can be caused by being overweight, a lack of exercise and regularly eating foods with large amounts of cholesterol. These include animal organs, egg yolks and high-fat dairy products. Some people, however, have high cholesterol levels for no apparent reason.
HDL Cholesterol
HDL cholesterol is the good cholesterol, as it helps remove excess cholesterol from the bloodstream for return to the liver. HDL cholesterol should be greater than 60 mg/dL and less than 35 is considered high risk. Low HDL cholesterol is associated with an increased risk for heart disease, according to the American Heart Association, and high levels appear to protect against heart attack. People can raise HDL cholesterol levels by eating whole grains, legumes, green vegetables, onions, fruit and walnuts. Cooking with olive and flaxseed oil and using these oils for salad dressing also can help. Eating fatty fish such as salmon and tuna is beneficial for raising HDL cholesterol. Additionally, regular exercise raises HDL cholesterol.
Total Cholesterol and Cholesterol Ratio
Total cholesterol and LDL/HDL ratios are other components of cholesterol, as their measurement provides further indication about healthy lipid levels. Total cholesterol should be less than 200 mg/dL, and total cholesterol of 240 or greater is considered high risk. The LDL/HDL ratio should be 0.5-3.0. A healthy reading, for example, would be 120 LDL/80 HDL, for a ratio of 1.5. A ratio greater than 6 is considered high risk.
Triglycerides
Triglyceride levels should be less than 200 mg/dL, and greater than 400 mg/dL is considered high risk. High levels of triglycerides can increase the risk of cardiovascular disease like LDL cholesterol does, according to the Mayo Clinic. High triglyceride levels may indicate Type 2 diabetes, kidney or liver disease, or low levels of thyroid hormones. As with cholesterol, triglycerides can be reduced by exercising, eating properly and maintaining a healthy weight.
