Fats are divided chemically into three kinds: the saturates and polyunsaturates, now so familiar, and the less publicized monounsaturates. Saturated fats are the baddies, furring the arteries by raising cholesterol levels until a clot or blockage leads to a heart attack. Polyunsaturates don’t fur blood vessels, and may even, it is thought, act as an antidote to the process (though this is not yet proven). Polyunsaturates also supply us with the essential fatty acids (EFAS: linoleic, linolenic and archidonic acids) which are necessary to healthy blood flow and blood vessels. Monounsaturates are neutral in health terms.