I’m a Dietitian. Here’s What I Really Think About Seed Oils

I’m a Dietitian. Here’s What I Really Think About Seed Oils originally appeared on Men’s Fitness.

Close to 30 years ago, when I decided to go to school to become a dietitian and earn a Ph.D. in exercise physiology, I hoped to learn evidence-based nutrition and knowledge and learn how to apply it to clients. And I did.

Now, though, I’m constantly exposed to a lot of opinions about science—both from clients and in my everyday life—that are, let’s say, less based in evidence than what I learned in school and beyond with my continuing education. Some may have some tiny, distant level of truth, but are preached about like they’re gospel. Ultimately, the less people know, the more confidently they know it.

And that brings me to this topic: Seed oils.

What Are Seed Oils?

Seed oils are common cooking oils that have been around since the early 1900s. As the name implies, the demonized category of seed oils come from the seeds of various plants. Some of the top seeds and resultant oils include canola, corn, cottonseed, grapeseed, sunflower, soybean, safflower, rice bran and peanut, among others.

Seed oils tend to be rich in a type of fat called polyunsaturated fats. You are likely familiar with saturated fats—like butter, beef tallow, and coconut oil. Polyunsaturated fats are another category. Generally, the term refers to a type of healthy fat found in foods like fatty fish, walnuts, flaxseeds, and sunflower oil as examples. They contain essential omega-3 and omega-6 fatty acids, which support heart health, brain function, and inflammation control.

Why Are Seed Oils Controversial?

Seed oil’s controversy is rooted in a lot of half-truths, misunderstandings and extrapolation of data without a true grasp of the science.

Yes, it’s true that seed oils are present in a lot of ultra-processed foods, and ultra-processed foods should be limited. But demonizing seed oils is like stepping over dollars to pick up pennies.

“The type of oil in which your food is cooked matters a whole lot less than the food itself—and your dietary pattern on the whole. Our diets aren’t built in a single ingredient or food, but rather overall patterns,” says Jacyln London, M.S., R.D.

In other words, is it the seed oil in the ultra processed food you’re eating, or is it the food as a whole? And how often is said food a part of your overall diet? I’d argue that a dietary pattern built around ultra-processed, fiber-free, low-protein, high-sugar foods are all more of a concern than the seed oil.

Let’s dig deeper into some of the myths around seed oils and the underlying truths.

Myth 1: Seed Oils are Inflammatory

Here’s where that confusion stems from. Seed oils are rich sources of omega-6 fats. Omega-6 fats are essential, meaning we have to get them from the diet since our bodies don’t make them. But most people eat a lot of them, as they’re present in eggs, poultry, nuts, seeds, and vegetable oils. Omega-3 fats are primarily from fish, flaxseed, leafy green veggies, walnuts, and others. Most people don’t eat nearly enough of these kinds of foods.

There are some data suggesting that dietary patterns where fat consumption is out of balance, meaning too many omega-6’s to too few 3’s, is linked to an increased risk of inflammation and chronic disease over time. But “the idea is mechanistic in nature and when it comes to health outcomes, which is what truly matters, people end up healthier when replacing less healthy fats with seed oils,” says Spencer Nadolsky, D.O., Obesity and Lipid Specialist and founder of Join Vineyard. “In fact, they show an improvement in health outcomes like improved lipids, lower rates of heart disease, and mortality when replace saturated fats with mono and polyunsaturated fats—that is, seed oils along with olive oil, avocado oil and others.”

Further, a study that was just published examined this very topic—inflammatory markers after supplementation with omega-3 or omega-6 fats—and found “no difference between treatments for any circulatory inflammatory markers.”

So, what does this mean? Ordering or preparing meals with more whole foods—like vegetables, seafood, pulses, nuts, seeds, a variety of lean proteins—while using a variety of fats and cooking oils (yes, including seed oils) will ensure you’re eating an anti-inflammatory diet overall.

Myth 2: Seed Oils are Full of Toxic, Poisonous Chemicals

Conventional seed oil extraction can include use of a chemical solvent, called hexane, to improve shelf life and flavor. Hexane can cause neurological and respiratory issues when inhaled in gas form. Yes, that sounds scary and dangerous, “but research has yet to show that trace exposure to hexane in food is harmful for human health,” says London. “Exposure route really matters when it comes to any substance, despite the way this is portrayed online.”

And, let’s be honest, eating seed oils doesn’t mean you’re inhaling hexane gas. If you’re still concerned, look for “cold pressed” oil, which is a solvent-free way to extract the oil you’ll be enjoying.

Myth 3: Seed Oils Are Rancid

Oils that are high in polyunsaturated fat (like seed oils) are more prone to oxidation when exposed to heat, light, and air. These aspects can form harmful compounds that contribute to inflammation over time. But consider that those elements—heat, light, and air—can all be controlled.

Look for cold pressed oils, store them in dark or opaque bottles in cool, dry places. Then also understand the smoke point of the oil used, which is the temperature at which the oil begins to smoke and break down. Sunflower oil comes to mind here, as it offers a higher smoke point than most and is also mostly made up of about 85 percent unsaturated fatty acids.

Keep in mind, despite being susceptible to oxidation, “the actual effect of seed oils on human health doesn’t necessarily translate to increased inflammation in the body,” London says. In fact, a 2025 study in the Journal of the American Medical Association showed that replacing saturated fat with unsaturated fats (like seed oils) was associated with lower risk of mortality.

Anything you remove from your diet is only as good for your health as what you replace it with and how often you consume it.

How does this apply to real life?

If you’re trading butter for canola or sunflower oil to saute your vegetables and eating them more often, you’re taking a positive step toward improving your health and reducing your risk of inflammation overall. If you’re choosing fries that are fried in beef tallow instead of a seed oil, that’s not going to make a huge impact on your inflammation.

Context matters.

The point?

Seed oils aren’t toxic.

Sure, if seed oils still concern you, olive oil and avocado can both do the job in the kitchen too. They’re both insanely healthy options that have numerous health benefits, when being subbed for more saturated fat rich oils.

Look for 100 percent extra virgin olive oil (EVOO) on the label and, similarly, look for 100% pure avocado oil. There’s numerous brands offering both; two I’m loving right now are Enzo’s Organic EVOO and Chosen Foods 100 Percent Pure Avocado Oil. Both are high quality with unique attributes – EVOO, a more flavorful add to any recipe (their Fresno Chili Crush Olive Oil is next level!) while avocado oil has a neutral flavor and a very high smoke point of up to 500 degrees.

Moral of the Seed Oil Story?

Overconsumption of anything, including calories themselves, can lead to detrimental effects. If you eat a lot of seed oil-filled ultra-processed foods, it’s very possible that you’ll experience some detrimental effects. I’d argue and very easily back up the argument with science that it’s not the seed oils themselves but instead the overall calorie load, added sugar, sodium, lack of fiber, and other ingredients I wouldn’t encourage people to eat on the regular.

I’m a Dietitian. Here’s What I Really Think About Seed Oils first appeared on Men’s Fitness on Jul 30, 2025

This story was originally reported by Men’s Fitness on Jul 30, 2025, where it first appeared.