Fats for the Brain, Part 2: Making Sense of the Seed Oil Controversy

Seed oils have become one of the most controversial topics in nutrition.  Some claim they're driving today's epidemics of heart disease, obesity, and chronic inflammation, while others point to the research that suggests they can be part of a healthy diet. 

With so much conflicting information, it's understandable to wonder what to believe.  In Part 1 of our Fats for the Brain series, we introduced four major types of dietary fat and how they affect brain health.  Here in Part 2, we're adding one more type, which may be the most talked-about group of all: seed oils.  We'll explore why they've become so controversial, what research says, and what it means for brain health. 

What Are Seed Oils and Omega-6 Fatty Acids? 

As their name suggests, seed oils are oils extracted from the seeds of certain plants.  Common examples include canola, corn, cottonseed, grapeseed, rice bran, safflower, soybean, and sunflower oils.  (For comparison, olive oil and avocado oil are extracted from the fruit of the plant rather than the seed.) 

Although seed oils contain a mix of different fats, they are best known for being rich in omega-6 polyunsaturated fatty acids, particularly linoleic acid.  Like omega-3s, omega-6s are considered essential fatty acids, meaning our bodies cannot make them and must obtain them through food. 

That distinction is important because omega-6 fats are not inherently harmful — they're essential nutrients required for normal growth, cell membrane structure, and many physiological processes.  On top of that, recent reviews continue to indicate that linoleic acid appears beneficial, not harmful, for cardiometabolic health when consumed in typical dietary amounts.¹ 

The real question isn't whether seed oils (and omega-6 fats by association) are good or bad, but how they're consumed and how they fit into a broader diet. 

The Seed Oil Controversy 

Despite containing an essential fatty acid, seed oils have become a highly discussed food.  These are the common claims surrounding seed oils: 

Many of these claims have picked up speed through social media, podcasts, blogs, and popular media, where health and wellness influencers can present them as clear explanations for complex health problems.  These messages can attract attention and spread quickly, but when compared with peer-reviewed scientific and clinical research, the difference between an online narrative and actual research is notable. 

Where Did These Claims Come From? 

Some of these controversial claims likely originate from how omega-6 fats are metabolized in the body.  The primary omega-6 fat found in seed oils, linoleic acid, can be converted into arachidonic acid, which the body uses to produce signaling molecules involved in inflammatory processes.²  This linkage to inflammation is where much of the confusion stems.  Because chronic inflammation is linked to conditions like cardiovascular disease, cognitive decline, and Alzheimer's disease, some claim that consuming more omega-6 fats could increase inflammation (due to arachidonic acid) and, in turn, increase disease risk. 

However, research doesn’t necessarily support this conclusion, since the roles of omega-6 fatty acids and arachidonic acid are much, much more complex, playing roles in driving inflammation, reducing inflammation, promoting healing, and important structural functions in cell membranes.² 

Simply put, current evidence has not found that moderate omega-6 intake increases inflammation or disease risk.  In fact, studies have shown the opposite: replacing foods high in saturated fat with foods rich in polyunsaturated fats, including omega-6 fats, is generally associated with better cardiovascular health.  Because heart and brain health are closely connected, these findings are also relevant to long-term brain health.  A 2024 review found no consistent evidence that higher omega-6 intake increases inflammatory markers, while a large 2025 study reported that replacing butter with plant oils was associated with lower mortality.^3,4  

Omega-6 and Omega-3: How Important is Balance? 

Both omega-6 and omega-3 fatty acids are essential, but modern diets generally provide much more omega-6 than omega-3.  Some estimates suggest that early human diets had an omega-6 ratio closer to 1:1 or 2:1, while Western diets may now reach as high as 10:1 to 20:1.^5,6  This change has led researchers to investigate whether the relative balance between these fats influences inflammation and long-term health.  

At this point, there’s no “ideal” omega-6:omega-3 ratio that’s been established by the medical community, and researchers continue to debate whether the ratio alone is an accurate indicator of a healthy diet.  For example, a seemingly “good” ratio could result from consuming very little of either fatty acid, while a higher ratio could be seen in a diet rich in heart-healthy linoleic acid but low in omega-3.  In other words, the ratio does not tell us enough about the quality or quantity of the fats being consumed.⁷  

For now, increasing omega-3 intake may be a more practical and evidence-based priority than broadly restricting omega-6-rich foods.  This could include eating fatty fish regularly and incorporating other omega-3 sources into the diet.  Whether reducing omega-6 intake provides additional benefits — and whether we should aim for a specific omega-6:omega-3 ratio — remains an active area of research.⁷  

If It's Not the Seed Oils, Then What’s the Problem? 

One reason the seed oil debate has become so complicated is that we rarely consume seed oils by themselves.  More often, they're found in foods like potato chips, french fries, packaged snacks, fast food, frozen meals, and baked desserts.  These foods are frequently used as examples when discussing the potential harm of seed oils. 

In Part 1 of this series, we mentioned the concept of the food matrix: a food's health effects are shaped not only by its individual nutrients, but also by how those nutrients interact in the food itself — demonstrating the importance of overall diet. 

Context matters.  Seed oils (and their accompanying omega-6 fats) might be unjustifiably “guilty by association” due to the unhealthy food matrix surrounding them. 

For example, many ultra-processed foods that contain seed oils are also high in refined grains, added sugars, sodium, and saturated fats, while providing relatively little fiber and other beneficial nutrients.  That makes it difficult to determine whether poorer health outcomes are related to the seed oils themselves or to the broader eating pattern in which they're commonly consumed.  At the same time, seed oils aren't found exclusively in ultra-processed foods.  They can also be ingredients in homemade vinaigrettes, hummus, canned beans, whole grain breads, and other foods that can fit within a generally healthy way of eating.⁸  

This doesn't mean the type of fat doesn't matter.  It means fats should be considered within the foods and dietary patterns they come from.  Both the nutrients themselves and the context of the diet contribute to long-term health. 

What Does This Mean for Brain Health? 

Much of the controversy surrounding seed oils and brain health stems from the role chronic inflammation plays in cognitive decline and Alzheimer's disease.  If omega-6-rich seed oils substantially increased chronic inflammation, concern about their effects on brain health would indeed be warranted. 

However, current research has not shown that consuming typical amounts of omega-6 fats from seed oils increases inflammation or dementia risk on its own.  Instead, research suggests that the bigger picture matters more.  Omega-3 fatty acids remain among the most well-studied nutrients for brain health, and ensuring adequate intake may be more beneficial than avoiding omega-6-rich foods altogether.⁹ 

What We Know About Seed Oils So Far 

The seed oil controversy is more complicated than many online discussions suggest.  Based on the current evidence, here are the essential points to keep in mind: 

So, rather than viewing seed oils as something to fear, focus on the quality of your overall diet.  Eating fatty fish regularly, choosing healthy oils in place of saturated fats when appropriate, limiting ultra-processed foods, and following research-backed eating patterns such as the Mediterranean or MIND diet are likely to have a much greater impact on long-term brain health than eliminating a single ingredient.    

Never Miss a Day of Brain Support  

A healthy diet remains the foundation of brain health, but eating enough brain-supporting foods every day isn’t always easy.  RELEVATE was designed to complement a healthy diet by providing 17 nutrients commonly found in Mediterranean and MIND-style eating patterns.  When paired with a healthy lifestyle, it can help support cognitive function, everyday energy, and healthy aging. 

Brain Health Kitchen Extra Virgin Olive Oil is another way to support a brain-healthy eating pattern.  Organically grown, harvested, and cold-pressed in Tuscany, Italy, it delivers a high-polyphenol nutritional profile and fits naturally into Mediterranean and MIND-style meals.    

References: 

1. Visioli, F. & Poli, A. Omega 6 fatty acids: helpful, harmless or harmful? Curr. Opin. Clin. Nutr. Metab. Care 28, 114–120 (2025). 

2. Poli, A., Agostoni, C. & Visioli, F. Dietary Fatty Acids and Inflammation: Focus on the n-6 Series. Int. J. Mol. Sci. 24, 4567 (2023). 

3. Petersen, K. S. et al. Perspective on the health effects of unsaturated fatty acids and commonly consumed plant oils high in unsaturated fat. British Journal of Nutrition 132, 1039–1050 (2024). 

4. Zhang, Y. et al. Butter and Plant-Based Oils Intake and Mortality. JAMA Intern. Med. 185, 549 (2025). 

5. Navneet, N. The Evolution of Omega-3 to Omega-6 Ratios: From Ancestral Diets to Modern Imbalances. J. Neonatal Surg. 14, 1111–1121 (2025). 

6. Schulze, M. B., Minihane, A. M., Saleh, R. N. M. & Risérus, U. Intake and metabolism of omega-3 and omega-6 polyunsaturated fatty acids: nutritional implications for cardiometabolic diseases. Lancet Diabetes Endocrinol. 8, 915–930 (2020). 

7. Cao, M. et al. Impact of dietary n-6/n-3 fatty acid ratio of atherosclerosis risk: A review. Prog. Lipid Res. 95, 101289 (2024). 

8. Nagra, M., Goldman, D. M., Belury, M. A. & Messina, M. Concerns about the health effects of industrially produced seed oils are without scientific foundation: a scoping narrative review of the clinical and observational evidence. Crit. Rev. Food Sci. Nutr. 1–61 (2026) doi:10.1080/10408398.2026.2657527. 

9. Wei, B.-Z., Li, L., Dong, C.-W., Tan, C.-C. & Xu, W. The Relationship of Omega-3 Fatty Acids with Dementia and Cognitive Decline: Evidence from Prospective Cohort Studies of Supplementation, Dietary Intake, and Blood Markers. Am. J. Clin. Nutr. 117, 1096–1109 (2023).