Seed Oils: Are They Really Bad for You? What the Science Actually Says
No one could have predicted the war on plant oils, but here we are, arguing whether or not you should consume an oil from a plant vs. an oil from animal fat. Registered dietitians everywhere are committed to setting the record straight on the truth about seed oils and what’s being said on social media.
What is a Seed Oil?
A seed oil is an oil extracted from the seeds of specific plants. Some of the most common are soybean, canola, grapeseed, peanut, and corn oils. They are considered unsaturated fats and typically contain a mixture of essential fatty acids such as omega-6 and omega-3 fatty acids. They are called “essential” because we can’t make them, we need to get them from food.
Omega-3 vs. Omega-6: What People Get Wrong
Omega-3 fatty acids get a lot of love. They are the kind found in salmon, flaxseed, and walnuts. They are known to be anti-inflammatory and praised in the nutrition world.
mega-6s are also anti-inflammatory; however, somewhere along the line, these were labeled as pro-inflammatory, and the demonization began (remember the egg debate and cholesterol? We’re still trying to clean up that mess). The research simply doesn’t support this notion.
Here’s the truth. Both omega-3 and omega-6 fatty acids support brain health, metabolism, vision, immunity, and overall cellular function.
The Case Against Seed Oils—And Why It Doesn’t Hold Up
Myth 1: Omega-6 Causes Inflammation
Omega-6 fatty acids make arachidonic acid (AA), which is used for metabolic health, brain health, and immunity. AA has been blamed for creating inflammation in the body and is one of the strikes used against seed oils. However, the exact opposite is true. AA is actively being shown in research to be a protector of cardiovascular disease, and in multiple studies where subjects were given AA directly, inflammation markers in the body did not increase. As with most facets of nutrition, the dose makes the poison. Too much or too little of anything can be problematic.
Myth 2: The Hexane Extraction Process Is Dangerous
The next point of contention is the extraction method used for seed oils. Hexane is a solvent used to extract oil from seeds. The oil goes through a refining process to remove the hexane and is used in both U.S. and European seed oil refining. Hexane residue levels are tested to be below the allowable level approved by the FDA. Regardless of this, there is always a choice to use cold-pressed seed oils if hexane is a concern. The choice to choose cold-pressed seed oils renders the hexane argument moot in the seed oil debate.
The Case for Seed Oils
The effect of seed oil on cardiovascular health is well studied, and the research is clear, and has been for over 30 years. Replacing animal (saturated) fat with seed oils (unsaturated) in the same amount lowers bad cholesterol levels and reduces the risk of heart disease. Furthermore, a recent 2025 study with over 220,000 adults concluded that replacing butter with plant-based oils, such as olive, soybean, and canola was associated with lower cancer deaths as well as lower risk of death from heart disease.
Studies have also looked at seed oils and their role in other inflammatory conditions, such as type 2 diabetes. Seeds oils were found to reduce oxidative stress (damage to cells), improve glycemic control, and decrease insulin resistance.
So Why the Confusion About Seed Oils?
Here's where the confusion started. Seed oils are cheap to produce, and because of that, manufacturers started using them in ultra-processed foods. When people eat more ultra-processed foods, their health declines. As we like to do in society, pinpointing a cause of this was necessary—seed oils were an easy scapegoat.
There seemed to be a linear relationship between the increased consumption of seed oils and the increased cases of chronic disease, along with a continued rise in obesity rates. What was also increasing was the intake of added sugar, sodium, and, up until 7 years ago, trans fat.
There is also a decline in physical activity, loss of social ties, and increasing isolation—all of which can impact physical health.
The Bottom Line: Should You Avoid Seed Oils?
The research on seed oils is so clear—if you replace equal amounts of animal fat in the diet with plant/seed oils, your risk of inflammatory chronic disease may decrease. Switching to a saturated fat isn’t the answer to combat chronic disease. Seed oils are not the dietary villain they are made to be on social media; there is no evidence to support it.
When looking to improve your health and reduce your risk of chronic disease, choose whole foods more often. Work towards decreasing the amount of ultra-processed and packaged foods in your diet, which will help to reduce the amount of added sugar, sodium and saturated fat, and don’t stress about that canola oil in your pantry.
Want to level up your nutrition game?
Join the Nutrition Group in the Team RWB app to connect with service members from all branches and eras. They share recipes, tips, and information. They also provide support as you work to achieve your fitness goals.
Sarah Pflugradt is a registered dietitian with a specialization in human performance. She is an Air Force vet, a military spouse, and a health promotion professor at American University in Washington D.C. She spends her free time cooking, writing, and watching her 3 kids compete in sports.
