NEW: Evidence from randomized controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis

Zoë Harcombe, Julien S Baker, Stephen Mark Cooper, Bruce Davies, Nicholas Sculthorpe, James J DiNicolantonio, Fergal Grace


https://pubmed.ncbi.nlm.nih.gov/25685363/


PURPOSE:

To examine the evidence from randomized controlled trials (RCTs) available to the US and UK regulatory committees at their respective points of implementation regarding National dietary guidelines introduced in 1977 and 1983 for the purpose of reducing coronary heart disease (CHD) by reducing fat intake. 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.


CONCLUSIONS:

2467 males participated in six dietary trials:

· Five secondary prevention studies.

· 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.


Dietary recommendations that were introduced for 220 million US and 56 million UK citizens by 1983 did not show any supporting evidence from RCTs.


IN PLAIN ENGLISH:

The dietary guidelines provided for reducing coronary heart disease were not supported by studies involving random controlled trials. No conclusive evidence that dietary fat intake is correlated to heart disease.