Revisiting the diet-heart hypothesis: critical appraisal of the Minnesota Coronary ExperimentBMJ 2017; 357 doi: https://doi.org/10.1136/bmj.j2108 (Published 01 June 2017) Cite this as: BMJ 2017;357:j2108
- Tumas Beinortas, physician and researcher1,
- Kamal R Mahtani, deputy director2,
- David Nunan2
- 1St James’s University Hospital, Leeds Teaching Hospitals NHS Trust, Leeds LS9 7TF, UK
- 2Centre for Evidence Based Medicine, Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
Several articles have concluded that associations between high cholesterol and premature death are lacking and advocate revision of current guidance advising low consumption (<10%) of saturated fat.123 Ramsden and colleagues recovered 45 year old data from the Minnesota Coronary Experiment, a randomised controlled trial conducted in state psychiatric hospitals and nursing homes in Minnesota, USA, and reassessed the effect of a diet rich in linoleic acid on serum cholesterol and mortality.3 The authors found that the diet lowered total cholesterol but did not reduce the risk of premature mortality and might even have increased it.
To change current consensus, however, these claims should be based on valid and reliable evidence. We performed a critical appraisal of the Minnesota Coronary Experiment using the methods and data provided in three publicly available descriptions of this trial: two peer reviewed papers (by Ramsden and colleagues3 and Frantz et al4) and a thesis by Broste,5 on which the primary data in the analysis by Ramsden and colleagues were based.
We used the Cochrane risk of bias tool to assess the internal validity of data from the original experiment (table 1⇓).6