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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)

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Editorial
Implausible discussions in saturated fat ‘research’; definitive solutions won’t come from another million editorials (or a million views of one)
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  1. David Nunan1,
  2. Duane Mellor2,
  3. Nicola Guess3,
  4. Ian M Lahart4
  1. 1 Centre for Evidence-Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
  2. 2 Coventry University, Coventry, UK
  3. 3 Division of Diabetes and Nutritional Sciences, Kings College London, London, UK
  4. 4 Faculty 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

https://doi.org/10.1136/bjsports-2018-099799

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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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