MedicalResearch.com: What are the main findings of the study?
Dr. Chowdhury: Total saturated fatty acid, whether measured as a dietary intake variable or in the bloodstream as a biomarker, was not associated with coronary disease risk in combining all available prospective observational studies. Similarly, there were non-significant overall associations in the prospective studies that involved assessments of total monounsaturated fatty acids, long-chain omega-3 and omega-6 polyunsaturated fatty acids.
However, we found diversity in the observational associations between specific circulating long-chain omega-3 and omega-6 fatty acids with coronary risk, with some evidence that circulating levels of eicosapentaenoic and docosahexaenoic acids (ie, the two main types of long-chain omega-3 polyunsaturated fatty acids), and arachidonic acid are each associated with lower coronary risk. Similarly, within saturated fatty acids, there were positive, however, non-significant associations observed for circulating blood composition of palmitic and stearic acids (found largely in palm oil and animal fats, respectively), whereas circulating margaric acid (a milk fat) had a significant inverse association.
Additionally, when we investigated the randomised controlled trials that reported on the effects of omega-3 and omega-6 fatty acids on reducing coronary outcomes, there was no significant overall association observed.
MedicalResearch.com: Were any of the findings unexpected?
Dr. Chowdhury: The pattern of findings from this review does not lend support to cardiovascular guidelines that promote high consumption of long-chain omega-3 and omega-6 polyunsaturated fatty acids and that suggest reduced consumption of total saturated fatty acids. Also, interestingly, when specific fatty acid subtypes were examined, there was diversity in the associations across individual fatty acids with coronary risk within the same broad family of fatty acid considered.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Chowdhury: There was a lack of association for “total” fatty acid groups and an important heterogeneity of association across “individual” subtype fatty acids with in broad fatty acid groups. This suggests that the current (typically composite) nutrient-based guidelines should perhaps consider this diversity (and potential interplay) of different individual nutrients which may have divergent biological and health effects. We believe that a more “food-focused” approach should be considered so that the patients can consume the fatty acid food sources that are beneficial (or not harmful) to cardiovascular health. When certain foods such as red and processed meat are avoided, they should be replaced them with nuts, fatty fish, and healthy oils—but importantly not with white rice, white bread, potatoes, sugary drinks, or other refined carbohydrates.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Chowdhury: There were moderate amount of available data on some specific circulating fatty acids that future large-scale and more detailed studies should look at. Additionally, the effect of omega-3 and omega-6 fatty acids in general populations are required.