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What should we be telling our patients about saturated fat and cardiovascular risk? There have been highly publicised systematic reviews of observational data suggesting no relationship between saturated fat and all-cause mortality or coronary heart disease (CHD).1 ,2 This is sensational, but is it correct? Randomised controlled trials (RCTs) are better than observational studies at clarifying effectiveness of interventions, and large numbers of people have been involved in randomised trials of saturated fat reduction over periods of at least 24 months. What do trials tell us about the effects of saturated fat reduction on health? And if we cut down on saturated fat, does it matter what we eat in its place? To find out, we carried out a Cochrane systematic review of RCTs.3
We worked with the WHO Nutrition Guidance Expert Advisory Group (WHO NUGAG) to ensure the review accurately assessed effects of reducing saturated fats on all-cause mortality, cardiovascular morbidity and other health outcomes, and to consider the differential effects on health outcomes of replacement of the energy from saturated fat by polyunsaturated fats, monounsaturated fats, carbohydrates or protein. Review methods followed the Cochrane Handbook for Systematic Reviews of Interventions (http://community.cochrane.org/handbook). The inclusion criteria for the Cochrane review are summarised in table 1, along with key review results.3
Meta-analysis of the 15 included RCTs did not suggest that reducing saturated fat altered risks of all-cause mortality, cardiovascular mortality, CHD mortality, CHD events, non-fatal myocardial infarction (MI) or stroke, but there was a 17% reduction in people experiencing cardiovascular disease (CVD) events and a marginal effect (suggesting a 10% reduction) on those experiencing MI (fatal or non-fatal). In this context we defined CVD events as including …
Collaborators George Davey Smith.
Contributors This editorial was planned and written by LH, NM and AA, and based on the systematic review planned, conducted and reported by LH, NM, AA and George Davey Smith.
Competing interests None declared.
Provenance and peer review Commissioned; externally peer reviewed.
↵i Please note that de Souza's results compare high saturated fat with low saturated fat intakes, while our systematic review of RCTs assesses effects of reducing saturated fat (effectively compares low saturated fat intake with high intake), so the RRs will be inverted. It is difficult to compare these directly but confidence intervals appear to overlap for all outcomes.
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