Cholesterol is an essential component of every cell membrane in your body, the (some people consider it rather important) brain, while only 2% of body weight contains 25% of the total cholesterol in your body. A sustained and highly successful campaign to lower cholesterol has had next to no effect on heart disease rates.  In fact there is recent and accumulating evidence that one should be more concerned over an excessively low cholesterol than an excessively high cholesterol.  There is an interesting writeup on this topic at the health Journal club where MIT research scientist Stephanie Sennef looks into the topic of cholesterol-lowering in general and Statin drugs in particular.