Current guidelines that promote high consumption of polyunsaturated fatty acids and low consumption of total saturated fats to reduce the risk of cardiovascular disease are based on inadequate evidence, a new analysis concludes (Chowdhury et al., 2014).
Nutritional guidelines generally encourage eating a relatively low amount of saturated fats such as butter in favour of polyunsaturated fat such as olive oil and sunflower oil. However, guidance about the optimum amounts and types of fatty acids that people should consume varies from country to country.
The systematic review and meta-analysis, published in the Annals of Internal Medicine, included studies involving more than 600 000 people in 18 countries. The researchers found no association between total saturated fatty acid consumption and coronary risk when they analysed 32 observational studies of fatty acids in dietary intake and 17 observational studies of fatty acid biomarkers. However, total intake of trans fats, found in some processed foods, was associated with coronary disease risk.
The researchers, led by Rajiv Chowdhury from the University of Cambridge, also found that higher intake of polyunsaturated fats did not offer any protection against heart disease. They found some evidence that circulating levels of two main types of long chain omega 3 polyunsaturated fatty acids and arachidonic acid are each associated with lower coronary risk. However, their meta-analysis of 27 randomised trials involving more than 100 000 participants indicated that taking supplements with these nutrients did not significantly reduce the risk of poor coronary outcomes.
The research was part funded by the British Heart Foundation. The foundation’s associate medical director, Jeremy 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.”
Wise, J. (2014) Evidence Does Not Support Guidelines on Saturated Fat, Researchers Say. British Medical Journal. BMJ 2014;348:g2238.
Chowdhury, R., Warnakula, S., Kunutsor, S., Crowe, F., Ward, H.A., Johnson, L., Franco, O.H., Butterworth, A.S., Forouhi, N.G., Thompson, S.G., Khaw, K-T., Mozaffarian, D., Danesh, J. & Di Angelantonio, E. (2014) Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-Analysis. Annals of Internal Medicine. 160(6), pp.398-406. doi:10.7326/M13-1788