Adapted from BMJ 9 Feb 13 Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis. Christopher E Ramsden et al
Despite lack of evidence to the contrary I still see NHS dieticians telling patients to avoid naturally occurring saturated fat such as butter, cream and the fat in animal meats. This study didn’t get much publicity at the time so here it is again.
The question was, does increasing dietary omega 6 linoleic acid in the place of saturated fat reduce the risk of death from coronary heart disease?
What happened was that in the Sydney Diet Heart Study, a RCT done between 1966 and 1973, saturated fat (thought to produce heart attacks) was replaced by omega 6 fatty acids from Safflower oil ( vegetable oil and margarines, thought to be heart healthy). Although the blood cholesterol levels decreased in the intervention group, deaths from all causes, coronary heart disease and cardiovascular disease, all increased.
The subjects were all men aged 30-59 who had had a recent heart attack. As an example, all cause mortality was 17.2% in the intervention group compared to 11.8% in the control group. Results for cardiovascular disease were similar.
It is mystifying that dietary advice telling people to swap lard for vegetable oils and butter for margarine is still going on. Very telling is that date that this study was done. The results would have been out by 1975.