Saturated fat and heart disease
“Guidelines urging people to avoid fat to stave off heart disease ‘are wrong’” reported the Daily Mail on 18th March. This was one of several news stories reporting the results of a newly published systematic review on the association between fatty acids and coronary disease.1-4
The review found that trans fats significantly increased the risk of coronary disease, but found no significant association for saturated fat. While the results suggested a possible protective effect of eating omega-3 polyunsaturates, this was not statistically significant.5 A detailed critical abstract of the systematic review can be found here.
This was a thorough analysis of the published evidence, but as the review authors themselves noted, the included studies were not without limitations. Concerns about the duration and accuracy of collected dietary information, as well the possible influence of unmeasured factors create a degree of uncertainty around some of the results.
This uncertainty is reflected in comments from Professor Jeremy Pearson of the British Heart Foundation - which co-funded the study. Prof Pearson said “This analysis of existing data suggests there isn't enough evidence to say that a diet rich in polyunsaturated fats but low in saturated fats reduces the risk of cardiovascular disease.
“But large scale clinical studies are needed, as these researchers recommend, before making a conclusive judgement”.
Most of the media reports questioned the validity of existing recommendations to replace dietary saturated fats with polyunsaturated fats. However, dietary guidance varies between different countries and organisations. Current UK recommendations from NICE on the prevention of cardiovascular disease6 do not mention polyunsaturates; rather they seek to protect people from the now well-established harms associated with trans fats, and to reduce the proportion of food energy that comes from saturated fats.
This latest systematic review may raise questions about the impact of the latter recommendation, but the benefits of eating less fat extend beyond direct correlations with heart disease. Broader recommendations around eating a healthy, balanced diet, being physically active and not smoking are unlikely to change anytime soon. As is always the case with the results of dietary research, it is important to step back and look at the bigger picture.References
1. Saturated fat advice ‘unclear’. BBC News, 17th March 2014.
2. No link found between saturated fat and heart disease. Daily Telegraph, 18th March 2014.
3. Saturated fat DOESN’T cause heart disease after all. Daily Mail, 17th March 2014.
4. Saturated fats and heart disease: no link found. Sky News, 18th March 2014.
5. Chowdhury R, et al. Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-analysis. Annals of Internal Medicine 2014;160(6):398-406.
6. NICE Public Health Guidance 25: Prevention of Cardiovascular Disease.