The American Heart Association's rationale for recommending polyunsaturated fatty acids is primarily their LDL-lowering effect, but this drop may be a consequence of membrane stiffening.

“the main reason that the American Heart Association thinks that polyunsaturated fatty acids found in canola corn oil peanut oil soybean oil grapeseed oil what else cottonseed oil whatever are good for you is because they lower your LDL cholesterol but the homeoviscus model which is pretty darn interesting and compelling posits that when you eat those polyunsaturated fatty acids your body has to make the membranes essentially more stiff because those polyunsaturated fatty acids make the membranes too fluid in order to make the membranes more stiff your LDL cholesterol drops