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Implausible discussions in saturated fat ‘research’; definitive solutions won’t come from another million editorials (or a million views of one)
  1. David Nunan1,
  2. Duane Mellor2,
  3. Nicola Guess3,
  4. Ian M Lahart4
  1. 1Centre for Evidence-Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
  2. 2Coventry University, Coventry, UK
  3. 3Division of Diabetes and Nutritional Sciences, Kings College London, London, UK
  4. 4Faculty of Education, Health and Wellbeing, University of Wolverhampton, Walsall, UK
  1. Correspondence to Dr David Nunan, Centre for Evidence-Based Medicine, Nuffield Department of Primary Care Health Science, University of Oxford, Oxford OX2 6GG, UK; david.nunan{at}phc.ox.ac.uk

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The British Journal of Sports Medicine published an opinion editorial advocating a revision of public health guidance on saturated fat.1 Here, we offer a rebuttal, incorporating evidence-based principles absent in the original editorial, focusing on the quality of the evidence presented and we discuss contradictory evidence in relation to saturated fat, low-density lipoprotein cholesterol (LDL-C), specific dietary interventions and cardiovascular disease (CVD) alongside future directions. 

Effects of reducing saturated fat intake on CVD 

The authors cite a 2015 ‘landmark’ meta-analysis of observational studies showing a lack of an association between saturated fat consumption and both all-cause mortality and cardiovascular outcomes.2 According to best practice evidence-based methods, these types of studies provide low-quality evidence.3 Indeed, the authors of the cited meta-analysis reported that the likelihood of the reported associations was ‘very low’,2 meaning we can have very little confidence in the findings.

The authors have also overlooked a 2015 Cochrane meta-analysis of 17 randomised controlled trials (RCTs; ~59 000 participants) which showed moderate quality evidence that long-term reduction of dietary saturated fat lowered the risk of cardiovascular events (number needed to treat=14) but had no statistical effect on all-cause mortality or cardiovascular outcomes.4 In pre-planned subgroup analyses, cardiovascular events were reduced when saturated fat was replaced by polyunsaturated fat (but not by carbohydrates, proteins or monounsaturated fat).4 This is a caveat that has been observed and emphasised by others and is well acknowledged in the field.5

To further support their view, the editorial authors turn to data from a 2004 post hoc observational study (low quality evidence) of postmenopausal women with established coronary heart disease, which showed an inverse relation between self-reported saturated fat intake and progression of atherosclerosis.6 Methodological weaknesses of this study include assessment of dietary intake only at baseline, with …

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