Cholesterol does not travel freely through the bloodstream. Instead, it is attached or carried by lipoproteins (lipo = fat) in the blood. There are three types of lipoproteins that are categorized based upon how much protein there is in relation to the amount of cholesterol.Low-density lipoproteins (LDL) contain a higher ratio of cholesterol to protein and are thought of as the âbadâ cholesterol. Elevated levels of LDL lipoprotein increase the risk of heart disease, stroke, and peripheral artery disease, by helping form cholesterol plaque along the inside of artery walls. Over time, as plaque buildup (plaque deposits) increases, the artery narrows (atherosclerosis) and blood flow decreases. If the plaque ruptures, it can cause a blood clot to form that prevents any blood flow. This clot is the cause of a heart attack or myocardial infarction if the clot occurs in one of the coronary arteries in the heart.High-density lipoproteins (HDL) are made up of a higher level of protein and a lower level of cholesterol. These tend to be thought of as âgoodâ cholesterol. The higher the HDL to LDL ratio, the better it is for the individual because such ratios can potentially be protective against heart disease, stroke, and peripheral artery disease.Very low-density lipoproteins (VLDL) contain even less protein than LDL. VLDL like LDL has been associated with plaque deposits.Triglycerides (a type of fat) may increase cholesterol-containing plaques if levels of LDL are high and HDL are low.Total cholesterol score is the sum of HDL cholesterol, LDL cholesterol and 20% of triglycerides as determined by a blood test. A high score indicates an increased risk for developing cardiovascular disease and/or strokes. Chart of LDL and HDL Cholesterol NumbersChart courtesy of the National Institutes of Health.