Cholesterol has become a huge buzzword among physicians who are constantly warning their patients about the dangers of high cholesterol. Too much cholesterol contributes to hardening of the arteries. Essentially it can lead to heart disease, which is the top killer of adults in the United States. Total cholesterol should be no higher than 200 mg/dL. LDL levels should not exceed 100 mg/dL. But what makes for "good" and "bad" cholesterol? Low-density lipoproteins might be a mouthful, but it's an important term to familiarize yourself with. Lipoproteins are what carry cholesterol through the bloodstream, and LDL cholesterol tends to build up on the walls of the arteries that feed the heart and brain. Arteries can harden and get blocked as a result of this plaque buildup and cause a heart attack or stroke, which is why LDL is the "bad" cholesterol.