Recently, seed oils—like canola, sunflower, safflower, and soybean oil—have become a hot topic. Are they really bad for you? Let's review the research.
As a registered dietitian, I frequently hear questions about which dietary fats are "good" or "bad" for heart health. Recently, seed oils—like canola, sunflower, safflower, and soybean oil—have become a hot topic. Claims linking these oils to inflammation and chronic disease have flooded social media, adding to the growing list of foods the internet insists you should “never eat again.” These assertions can be confusing and may lead patients to make drastic dietary changes that are not supported by scientific evidence.
You’ve likely come across the posts, heard the claims, and found yourself wondering: Are seed oils really bad for you? So, let’s begin to examine what the evidence really says, to dispel some of the myths surrounding seed oils, and explore their role in heart health. We want to give you the facts, so that you can make informed, evidence-based choices that are in line with your personal health and nutrition goals.
Image Source: Margaret Schroeder, MPH, RDN, LDN
What Are Seed Oils?
Seed oils are extracted from the seeds of plants like canola, soybean, sesame, corn, sunflower, or safflower. A large body of research supports the use of seed oils for their high polyunsaturated fat content, particularly omega-6 linoleic acid, which has been linked to health benefits such as: Reduced low density lipoprotein (LDL) or “lousy” cholesterol, improved heart health, lower risk of cardiovascular disease, stroke and type 2 diabetes, and potential anti-inflammatory effects in proper ratios with omega-3s. In fact, in a recent 2025 study, adipose tissue content of linoleic acid was inversely associated with all-cause mortality.
Image Source: Margaret Schroeder, MPH, RDN, LDN
Why are Seed Oils Controversial?
Seed oils are widely used in cooking and food production due to their affordability, versatility, and high smoke-point – this means that they are also used in the production of many processed and packaged foods. Ultra-processed foods have been associated with an increased risk of cancer, stroke, obesity, type 2 diabetes, high blood pressure, and other chronic health conditions. Because many highly processed foods contain seed oils, this contributes to the perception that seed oils are “unhealthy.” However, it’s important to take a step back and recognize the bigger picture. Ultra-processed foods, such as chips, packaged baked goods, sugary cereals, and processed meats or cheeses, are often also very high in sodium, added sugars, saturated fats, dietary cholesterol, and/or refined carbohydrates. These are ingredients that we know for a fact can negatively impact health when consumed in excess. Diet patterns that include ultra-processed foods are linked to poorer health outcomes, but the reality is that seed oils themselves are unlikely to be the culprit.
In fact, the science overwhelmingly shows us that when used in moderation, these oils can have a healthy place in our diet, and in many ways, can even benefit our health. Thus, while critics like to claim that the processing of seed oils, and the high omega-6 content, promotes chronic disease and/or inflammation, the relationship between seed oils and our health is much more positive, and more complex, than these claims would suggest.
What does the Research Suggest?
- Seed Oils Are Not Inherently Harmful – Despite internet claims, scientific evidence supports the health benefits of seed oils, particularly their role in reducing LDL cholesterol and cardiovascular disease risk.
- Polyunsaturated Fats, Including Omega-6s, Are Beneficial – Linoleic acid, an omega-6 fatty acid found in seed oils, is essential for health and does not inherently cause inflammation when consumed in appropriate ratios with omega-3s.
- Ultra-Processed Foods Are the Bigger Concern – Many ultra-processed foods contain seed oils, but their health risks stem from the high sodium, saturated fat, dietary cholesterol, and added sugar content, rather than the seed oils themselves.
- Processing of Seed Oils Does Not Make Them Dangerous – While refining removes some nutrients, modern methods minimize harmful compounds like trans fats and environmental impurities. Cold-pressed and expeller-pressed options are available for those who prefer less processing.
- Cooking with Seed Oils at Normal Temperatures Is Safe – The claim that heating seed oils releases harmful toxins is overstated, as moderate cooking temperatures do not produce dangerous levels of byproducts like aldehydes.
- Replacing Saturated Fats with Unsaturated Fats Improves Heart Health – Swapping butter and coconut oil for seed oils can lower LDL cholesterol and reduce cardiovascular disease risk.
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Seed oils can be a beneficial part of a heart-healthy diet when used in moderation and as part of a balanced eating pattern like the Pritikin Eating Plan. The myths surrounding their potential harms are often based on misinformation or isolated studies, while the broader body of evidence supports their role in improving cholesterol levels and reducing cardiovascular risk. While oils, including seed oils, provide essential fats, they are calorie-dense and should be consumed mindfully to support heart health and weight management. Rather than blaming seed oils for chronic ailments without the evidence to back this claim up, we should instead focus on overall dietary patterns that prioritize nutrient-rich, minimally processed foods, and minimize ingredients that we do know are linked to chronic disease. For optimal health, it’s important to limit or avoid foods high in sodium, saturated fat, trans fat, dietary cholesterol, and added sugars. The Pritikin Eating Plan helps you lower risk for chronic disease by emphasizing whole, mostly plant-based foods such as fruits, vegetables, whole grains, lean proteins, and a variety of healthy fats from sources like seed oils. By adopting a more sustainable, holistic approach—emphasizing balanced nutrition, physical activity, good rest, and a healthy mindset—we can better support long-term heart health and overall well-being.
