Omega-3 Protect Against Heart Disease Risk: New Data from a Famous Study

A few days after its publication, the meta-analysis study on the role of saturated fatty acids and Omega-3 in cardiovascular diseases was corrected in some parts. In particular, the authors admitted that Omega-3s protect against coronary heart disease, contrary to what was previously stated.

The research, published on March 17 in the Annals of Internal Medicine, had immediately raised criticism from nutritionists and scientists who pointed out methodological flaws and issues in the final review. The study also gained significant media attention. By claiming that saturated fats are not very harmful to the heart and that polyunsaturated fats do not reduce cardiovascular risk, it completely contradicted the principles of healthy eating promoted for years.

Which points in the study were corrected?

Although many researchers called for the article’s retraction due to inadequate analyses, only modifications were made. One of the most substantial changes concerned the effect of Omega-3s. In the original publication, the association between their consumption and reduced coronary risk was not statistically significant, likely due to errors in data input from a Danish study. The corrected version instead reported the protective effect of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) on the heart, substantially changing the final message. The corrected publication included a link to a 2013 article by one of the coauthors, highlighting a 27% mortality reduction in elderly and adults with high blood Omega-3 levels. Regarding the relationship between fatty acids and sudden cardiac death, new inclusion criteria raised the number of participants from 103,052 to 105,085 and coronary attacks from 5,726 to 6,229.

Omega-3 Protect Against Coronary Risk

In the conclusion of the original article, the authors stated they did not support guidelines promoting polyunsaturated fat consumption and saturated fat reduction in relation to cardiovascular health. The slightly revised conclusion no longer “fully” rejects guidelines, stating instead that consuming foods containing Omega-3 reduces coronary heart disease risk. The final sentence, where the authors suggested revising nutritional guidelines, was removed from the updated article.

Greater Attention from Scientists and Journalists

This episode highlighted, as suggested by Walter Willett, professor at Harvard University, that meta-analyses often are not applicable to nutrition studies. As in this case, important data are sometimes omitted from analyses. Regarding this, Robert Heaney, professor at Creighton University, published six guidelines for researchers to properly conduct meta-analyses in nutrition. Willett also argued that the article should be retracted rather than just corrected. While the discovery gained significant media attention and caused consumer confusion, it is unlikely that the public will be informed about the study’s corrections. Responsibility for such transparency in the future lies not only with scientists but also with journalists and communicators.

Source: Rajiv Chowdhury, MD, PhD; Samantha Warnakula, MPhil; Setor Kunutsor, MD, MSt; Francesca Crowe, PhD; Heather A. Ward, PhD; Laura Johnson, PhD; Oscar H. Franco, MD, PhD; Adam S. Butterworth, PhD; Nita G. Forouhi, MRCP, PhD; Simon G. Thompson, FMedSci; Kay-Tee Khaw, FMedSci; Dariush Mozaffarian, MD, DrPH; John Danesh, FRCP; and Emanuele Di Angelantonio, MD, PhD. “Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-analysis” Ann Intern Med. 2014;160(6):398-406-406. doi:10.7326/M13-1788