Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis
- Zoë Harcombe1,
- Julien S Baker1,
- Stephen Mark Cooper2,
- Bruce Davies3,
- Nicholas Sculthorpe1,
- James J DiNicolantonio4 and
- Fergal Grace1
- 1Institute of Clinical Exercise and Health Science, University of the West of Scotland, Hamilton, Lanarkshire, UK
- 2Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, UK
- 3University of South Wales, Pontypridd, UK
- 4Saint Luke's Mid America Heart Institute, Kansas City, Missouri, USA
- Correspondence to Zoë Harcombe;
Objectives National dietary guidelines were introduced in 1977 and 1983, by the US and UK governments, respectively, with the ambition of reducing coronary heart disease (CHD) by reducing fat intake. To date, no analysis of the evidence base for these recommendations has been undertaken. The present study examines the evidence from randomised controlled trials (RCTs) available to the US and UK regulatory committees at their respective points of implementation.
Methods A systematic review and meta-analysis were undertaken of RCTs, published prior to 1983, which examined the relationship between dietary fat, serum cholesterol and the development of CHD.
Results 2467 males participated in six dietary trials: five secondary prevention studies and one including healthy participants. There were 370 deaths from all-cause mortality in the intervention and control groups. The risk ratio (RR) from meta-analysis was 0.996 (95% CI 0.865 to 1.147). There were 207 and 216 deaths from CHD in the intervention and control groups, respectively. The RR was 0.989 (95% CI 0.784 to 1.247). There were no differences in all-cause mortality and non-significant differences in CHD mortality, resulting from the dietary interventions. The reductions in mean serum cholesterol levels were significantly higher in the intervention groups; this did not result in significant differences in CHD or all-cause mortality. Government dietary fat recommendations were untested in any trial prior to being introduced.
Conclusions Dietary recommendations were introduced for 220 million US and 56 million UK citizens by 1983, in the absence of supporting evidence from RCTs.
- Received September 18, 2014.
- Revision received November 26, 2014.
- Accepted December 2, 2014.
- Published 9 February 2015
- Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions
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