Another way in which polyunsaturated cooKing oils are oxidized is by repeated re-use and re-heating, such as was commonly practiced in Great Britain during the war. It would be reasonable to regard this as a bad and possibly dangerous habit, whether owing to oxidation of PUFA or of some other constituent of cooking oils.

No convincing case has been made that PUFA cause either premature ageing or cancer. Nevertheless, People consuming PUFA in quantity might consider taking supplements of vitamin E and should bear in mind the view that saturated, monounsaturated and polyunsaturated fatty acids should be consumed in equal amounts.

Concern about the possible danger of PUFA nearly fades into insignificance when compared with our ignorance about the fat composition of many widely consumed prepared foods. The term "Vegetable oil" may include coconut oil believed to be a constituent of many ice creams, "non dairy creamers," confections and cooking oils. Yet coconut oil is 85% saturated, has a particularly low iodine-value and contains larger amounts of palmitic and lauric acids. Palmitic and myristic acids are regarded as particularly potent atherogenic agents, and the level of myristic acid is raised in the serum of patients with ischaemic heart disease. Its composition makes coconut oil as even less desirable component of the diet than dairy fats, beef-fat, and the like. If people are consuming more vegetable oils. They should insist on eating the right sorts-such as corn oil, Soya-bean oil or preferably sunflower -seed oil-and not one that is more saturated than "animal fat." Rapeseed oil, owing to its high content of eruric acid, is known to be cardiatoxic in animals, so that it would seem to be a most undesirable vegetable oil. But how are public to know? They have a right to be informed about "Vegetable oils." Manufactures should declare the source and major composition of all fats used in foodstuffs. A deplorable commercial secrecy envelops the topic of edible fats.

The public are also ignorant about the extent and effects of hydrogenating PUFA to make them more solid. This is reputed to cause trans-unsaturated fatty acids to be formed. The cholesterol esters of these fatty acids are known to be highly fibrogenic. Again the facts should be divulged. It is disturbing that we consume commercially processed foods without considering what they contain, how they are made or what harm they may do.

Source: British Medical Journal 6th October 1973, Page 1 & 2