In the past half century, literally hundreds of well-run scientific studies, run by thousands of different researchers in dozens of different countries, have shown beyond a shadow of a doubt that having high cholesterol ? specifically, high levels of LDLs? is a strong warning that Mr. Heart Disease and Ms. Heart Attack are lying in wait somewhere in the future. Luckily, a similar long list of studies shows that what you eat and how you live your life to stay fit and relatively trim can help reduce your risk. Cholesterol is the Dr. Jekyll and Mr. Hyde of the nutrition world. This fat-like substance is both essential for your healthy body and potentially hazardous.Yes, you get some cholesterol from food, but the curious fact is that most of the cholesterol in your blood and body tissues is produced right in your very own liver. Your liver uses the proteins, fats, and carbohydrates in food to manufacture and churn out about 1 gram (1,000 milligrams) of cholesterol a day.Whether your cholesterol comes from food or your liver, it travels through your bloodstream in particles called lipoproteins, a name derived from lipos (the Greek word for ?fat?) and protos (Greek for ?first? or ?most important?).The fatty substances in lipoproteins include cholesterol and triglycerides, the most common fatty substance in the human body.The proteins that combine with fats to produce lipoproteins are called apolipoproteins, often abbreviated as apo. Lipoproteins develop through five distinct phases as they mature into the particles that carry cholesterol around your body:chylomicron become a VLDL, then an IDL, then an LDL, and finally, maybe, an HDL.