What is more healthy: unsaturated, or polyunsaturated fat?

Length of fat: Polyunsaturated fats are longer than monounsaturated fats. Both are healthier alternatives to animal fate-saturated fats.

PUFA Toxicity: Most people in industrialized countries get too much polyunsaturated fat of the omega-6 kind: from either natural or partially hydrogenated corn, soy, cottonseed or safflower oils. Only 1% of dietary calories is required as polyunsaturates and most modern diets supply 10% or more. These fats oxidize themselves (the same process makes oil-based paint dry) and increase the need for anti-oxidants.