Recently, seed oils—such as sunflower, safflower, canola, and soybean oil—have been targeted by certain health influencers and diet trends as being « toxic » or « inflammatory. » Claims often centre around their omega-6 fatty acid content, perceived overprocessing, or alleged contribution to chronic diseases. However, these claims often lack scientific support. Let’s dive into the research to separate myth from fact.
The role of Omega-6 fatty acids
A major point of contention with seed oils is their high content of omega-6 fatty acids, particularly linoleic acid. Omega-6 is a type of polyunsaturated fat that plays essential roles in brain function, growth, and development. Critics argue that omega-6s promote inflammation, but this misrepresents their biological role. According to a review published in Circulation (2010), increasing dietary omega-6 fatty acids is associated with reduced risk of cardiovascular disease. The study analysed data from large-scale trials and concluded that omega-6s are beneficial when consumed as part of a balanced diet, not harmful as some claim.
It is important to note that inflammation in the body is a complex process. Omega-6 fatty acids can contribute to pro-inflammatory and anti-inflammatory pathways, depending on context. What matters most is the overall balance of omega-3 to omega-6 fatty acids. Rather than eliminating seed oils, a practical approach is to increase omega-3-rich foods like fatty fish, flaxseeds, and walnuts to improve this ratio.
Seed oils and heart health
Seed oils are often vilified for their supposed role in heart disease. Yet, research consistently shows the opposite. For example, a meta-analysis in The Journal of Clinical Lipidology (2018) found that replacing saturated fats with polyunsaturated fats from sources like seed oils reduces LDL (« bad ») cholesterol and lowers cardiovascular risk. Canola oil, in particular, is endorsed by several health organisations for its favourable fatty acid profile and cholesterol-lowering effects.
Addressing concerns about processing
Another common critique is that seed oils undergo extensive processing, including chemical extraction and deodorisation. While it’s true that these processes are part of production, the resulting oils remain safe and nutrient-rich. Refined seed oils are free from harmful trans fats and are fortified with vitamin E, a powerful antioxidant. Furthermore, cold-pressed and minimally processed versions of seed oils are available for those who prefer less refinement.
Real-world evidence
Public health data also highlight the positive impact of seed oil consumption. In countries like Japan and Spain, where diets are rich in plant-based oils, heart disease rates are significantly lower compared to regions with high saturated fat intake. Additionally, replacing animal fats with seed oils has been shown to improve lipid profiles and support weight management in numerous studies.
Conclusion
The claim that seed oils are inherently harmful is not supported by scientific evidence. When consumed as part of a balanced diet, seed oils provide essential fatty acids, improve heart health, and support overall well-being. Instead of demonising a single food group, it’s more productive to focus on eating a variety of nutrient-dense foods while limiting ultra-processed snacks and added sugars. By embracing a holistic approach, seed oils can be part of a healthy, sustainable diet.