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 …