What is the difference between LDL and HDL?

LDL and HDL are delivery trucks for cholesterol, and the good-versus-bad labels come from the direction they drive. LDL - low-density lipoprotein - carries cholesterol from the liver out to tissues, and when there is too much of it, cholesterol deposits into artery walls, building the plaques that narrow arteries and cause heart attacks and strokes. NHLBI calls LDL the major cholesterol carrier and the primary treatment target. HDL - high-density lipoprotein - runs the reverse route, scavenging cholesterol from arteries and hauling it back to the liver for disposal, which is why higher HDL associates with lower risk. The nuance worth knowing: HDL's good reputation comes from observation - people with high HDL fare better - but trials of drugs that raise HDL failed to reduce heart attacks, which shifted thinking: HDL is a marker of a healthy system more than a lever to pull. LDL remains the actionable target - every proven therapy, from statins to diet, works by lowering LDL. The practical numbers: LDL under 100 optimal, under 70 if you already have heart disease; HDL 40-plus for men, 50-plus for women. Moving them: LDL falls with less saturated fat, more fiber - oats and beans genuinely bind cholesterol - and activity; HDL rises with exercise, not smoking, and modest healthy fats. And triglycerides matter alongside - high triglycerides with low HDL is the pattern insulin resistance produces. Pymander is a free AI doctor, 24/7 by text. Share your numbers, and it can help you read the direction of travel.