Seed Oils: Real Harm or Just Another Food Fear Fad?
Two health obsessions that I’ve never really understood are the supposed benefits of vitamin D (for every imaginable ill) and harm of seed oils. Dr. Bobby Dubois thinks a lot about the evidence behind health recommendations on his podcast. His research has led him to a pretty clear opinion about the role of seed oils in health and disease. Attentive Sensible Medicine readers will note that his take is a bit different from that expressed in a recent post. As we note in our about, “Once upon a time, that was how progress occurred, through dialogue. We work to nurture a home for this type of engagement.”
Adam Cifu
I enjoy eating and cooking. I like butter for sauteing and olive oil for many dishes. But, what about canola oil?
In recent years, seed oils like canola have become a hot topic among the alternative medicine community, with many claiming they cause inflammation, heart disease, diabetes, and other chronic health conditions–Is there evidence to support these claims? Social media is flooded with warnings from health “experts” about the so-called “hateful eight” oils—corn, canola, safflower, cottonseed, grapeseed, rice bran, soybean, and sunflower oils. It seems like many who raise this concern feel that the traditional medical approaches miss the mark and that many (most) illnesses might be prevented with better life choices.
As a physician, scientist, wellness/longevity podcaster, and Ironman Triathlete, I strongly support healthy life choices. But are the widely disseminated concerns about seed oils valid? Unlike many who theorize that they are dangerous (or only point to in vitro data), let’s dive into the evidence to explore whether seed oils are truly harmful or just another food fear fad.
What Are Seed Oils?
Seed oils are extracted from various seeds and have become a staple in the modern diet due to their affordability and versatility in cooking. Concerns have been raised that the chemicals used to extract the oils can harm us. Potentially those chemicals could harm the factory workers as they may be present in large quantities. But those chemicals have dissipated long before they arrive on the market shelf.
When saturated fats (e.g., butter, lard) were deemed unhealthy, seed oils became a popular alternative. However, many now claim that these oils are dangerous due to their polyunsaturated fats, specifically omega-6 fatty acids like linoleic acid. But does consuming seed oils lead to health problems?
The Basics of Seed Oils
Seed oils are a mixture of saturated, monounsaturated, and polyunsaturated fats. The main concern is about the polyunsaturated fats (PUFAs), specifically omega-6 fats like linoleic acid. Some argue that these fats promote inflammation and lead to chronic diseases. However, the situation is more nuanced.
First, omega-6 fats are essential fatty acids, meaning our bodies need them but can’t produce them. They play a vital role in skin health and cell membrane function. The concern some “experts” make is the changing balance between omega-6 and omega-3 fats in our diet. Historically, humans consumed roughly equal amounts of omega-3 and omega-6. Today, due to the prevalence of seed oils, we consume much more omega-6, which some fear may promote inflammation. But is there any evidence to support this?
The Evidence on Seed Oils and Health
Inflammation: In 15 randomized controlled trials, participants who replaced saturated fats with PUFAs, including those from seed oils, showed no significant increase in markers of inflammation. While lab studies (in vitro) have suggested that linoleic acid can cause inflammation in cells, these results haven’t been replicated in humans.
Heart Disease: If seed oils truly promoted inflammation, we might expect higher rates of heart disease in people who consume them. However, a meta-analysis of 30 observational studies across 13 countries found that higher levels of linoleic acid in the blood were associated with a lower risk of heart disease and stroke. Furthermore, a large randomized trial from the Minnesota Coronary Survey showed no difference in cardiac mortality between people consuming a diet rich in seed oils and those who didn’t.
Diabetes: Concerns about seed oils causing diabetes have also been refuted by large-scale studies. In the Nurses’ Health Study and the Health Professionals’ Follow-Up Study, people with higher linoleic acid intake actually had a lower risk of developing diabetes.
The Real Problem: Processed Foods, Not Seed Oils
While the evidence suggests that seed oils themselves are not harmful, the issue may lie elsewhere. Seed oils are inexpensive to produce, which has allowed the food industry to create a wide range of ultra-processed, calorie-dense foods like chips, cookies, and fried snacks. These highly processed foods may be the real culprits behind the rising rates of obesity, heart disease, and diabetes—not the seed oils themselves.
Calorie dense processed foods are designed to be irresistible, and their excessive consumption contributes to weight gain and poor health. So, while seed oils are a convenient and cost-effective ingredient, it’s their role in the creation of unhealthy, processed foods that’s likely the real problem.
What About Cooking with Seed Oils?
People have also expressed concern about what happens when you cook with seed oils. When oils are heated to high temperatures, they can produce harmful compounds like aldehydes and polycyclic aromatic hydrocarbons (PAHs). However, this occurs mainly at very high temperatures—above 450°F. Most cooking, including frying chicken, happens at much lower temperatures, typically around 325°F to 375°F, where the formation of harmful compounds is minimal.
Grilling a nice piece of salmon at high temperature can produce harmful byproducts—so likely the “problem” is not the type of oil (seed vs. avocado vs. olive vs. fatty fish) but rather what happens when we cook with it (at high temperatures). Since seed oils are inexpensive many restaurants use them and reuse them in deep fryers. Repeated use of the same oil at high temperatures can lead to accumulation of harmful byproducts.
Should You Avoid Seed Oils?
For the average person cooking at home, there’s little reason to fear seed oils. The amount of oil used in cooking is small, and as long as you’re not reusing oil repeatedly at high heat, the risk of harmful compounds forming is minimal. From the studies cited above, there is no apparent harm in using seed oils for salad dressing or small amounts when sauteing foods. That said, if you prefer to use olive oil or avocado oil, there’s no harm in switching—just be prepared for a higher price tag (2-4 times more costly).
Conclusion: Seed Oils Are Not the Enemy
Based on the available evidence, I don’t believe that seed oils are the health hazard they’ve been made out to be. Seed oils do not appear to cause inflammation, heart disease, or diabetes. Seed oils are problematic, but that reflects their role in processed foods. If you’re looking to improve your health, the best approach is to minimize ultra-processed foods, focus on whole, nutrient-dense options, and maintain a balanced diet.
In the end, the fear surrounding seed oils is more of a food fad than a legitimate health concern. I will continue to enjoy my sauteed vegetables and my salad dressing.
Dr. Bobby Dubois is a physician and scientist with 180 peer-reviewed publications on evidence-based medicine, appropriateness of care, and the value of health care interventions. He is also an Ironman Triathlete, and wellness/longevity/health podcaster and writer. To hear more health thoughts, listen to his podcast: Live Long and Well With Dr. Bobby.
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 | A guest post by
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In this column of Sensible Medicine, Bobby Dubois relies on two superficially reviewed references (i.e., without a critical evaluation of the cited evidence) to grant a surprising exoneration to one of the most significant contributors to modern disease. He cites 15 randomized clinical trials and 20 meta-analyses without providing the respective references, critically assessing their validity, or addressing the adverse effects documented in the evidence. This approach undermines the credibility of the argument he presents in defense of the serious precursors of arachidonic acid.
Fundamentally, it is difficult to argue that seed oils can be considered healthy. Originally used as industrial lubricants in machinery during the 1930s—rather than as food—they eventually became the basis for hydrogenated products like margarine. This shift replaced healthy saturated fats and was largely driven by misinformation propagated during the first half of the 20th century.
When combined with sugar—which accounts for 70% of the standard American diet—seed oils are likely contributors to 8 out of the 10 leading causes of disease and death globally ( https://bit.ly/EcheverryJ_2024_Falsehod_origin_diabesity_pandemic ).
While it is possible that seed oils are not as harmful as some theories and evidence suggest, it remains essential to thoroughly and rigorously evaluate the information cited in their defense.
Lastly, the author’s status as an Ironman is mentioned in his defense, but there is no evidence to suggest that being an Ironman represents a sustainable lifestyle or a crucial factor for achieving maximum longevity and quality of life. Evaluating the evidence supporting such claims is equally important to ensure that the arguments presented are scientifically robust.
I simply stopped using seed oils. I only use animal fat, butter, and cold pressed coconut nut oil.