ACI recognises National Cholesterol Education Month. Cholesterol is important to many bodily functions like the production of cell membranes and some hormones. Having too much of the "bad" cholesterol and not enough of the "good", can put us at risk for coronary heart disease. Low-density lipoprotein, or LDL, is known as "bad" cholesterol. High-density lipoprotein, or HDL, is known as "good" cholesterol. LDL (bad) cholesterol can slowly build up in the walls of the arteries of the heart and brain.