Here is an intriguing line of thinking: if we can identify unambiguously beneficial components of our metabolism, why not make artificial replicas and flood the body with them? "The particles that ferry cholesterol through the bloodstream are popularly known as 'bad' or 'good': bad if they deposit cholesterol on vessel walls, potentially clogging them; good if they carry the cholesterol on to the liver for excretion. Now scientists have created tiny particles in the laboratory that mimic those good carriers, scooping up the cholesterol before it can grow into dangerous deposits of plaque. The surfaces of these new particles are coated with fats and proteins so they can bind tightly with the sticky cholesterol to transport it through the bloodstream. ... Researchers have endowed these artificial particles with the same properties as natural particles that circulate in the blood, [called] high-density lipoproteins, or HDL ... The artificial carriers can clean up sites where plaques can otherwise rupture, leading to strokes and heart attacks."