The accumulating evidence on the lack of association between eating saturated fat and heart disease has featured in previous posts.  An intriguing re-analysis of an RCT carried out in nursing homes and hospitals for mental illness has recently been published in the BMJ. In this trial saturated fats were replaced in the diet by polyunsaturated fats. The now familiar story was confirmed; yes, the polyunsaturated fat is associated with lower cholesterol levels, but no, there was no hint of a decrease in heart attack or all-cause mortality in the low fat group. The authors then carried out a systematic review, finding five RCTs examining the same hypothesis. They provided strikingly similar results; the meta-analysis corroborated the nursing home study. One intriguing point made in an accompanying editorial  is that the climate was so heavily slanted towards the fat and cholesterol hypothesis that the trial, which ended in 1973, was not published until 1989. But opinion has eventually caught up with the evidence and US dietary guidelines have finally removed dietary cholesterol and fat from the list of foods that should be avoided. But note this point – the fact that saturated fats are no worse than polyunsaturated fats does not mean that there are not yet better sources of calories. And, yes, plants are better than meat, butter, etc. They are boring to eat, of course, but they are probably the best source for most of our calories.
— Richard Lilford, CLAHRC WM Director
- Lilford R. More on Diet. NIHR CLAHRC WM News Blog. 14 August 2015.
- Lilford R. On Diet Again. NIHR CLAHRC WM News Blog. 23 October 2015.
- Ramsden CE, Zamora D, Majchrzak-Hong S, et al. Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73). BMJ. 2016; 353: i246.
- Veerman JL. Dietary fats: a new look at old data challenges established wisdom. 2016; 352: i1512.
- US Department of Health and Humans Services and US Department of Agriculture. 2015-2020 Dietary Guidelines for Americans. 8th Washington, D.C.: USDA, 2015