I didn’t used to think much about cooking oils.

For most of my life, I grabbed whatever was in the pantry—canola, vegetable, maybe some “heart-healthy” blend in a plastic bottle—and used it without a second thought. It wasn’t something I questioned; it wasn’t something anyone around me questioned. The bottle said it was good for you, the dietary guidelines agreed, and that was the end of the conversation.

That changed for me around 2018 when I went carnivore and started paying attention to what I was actually putting into my body. Once I cut seed oils out of my own diet, the difference was hard to ignore—less inflammation, fewer aches, better skin, things I hadn’t even realized were problems until they weren’t anymore. I had my own experience, I had the research I’d been reading, and I had a strong suspicion that these oils were doing more harm than most people realized.

Then I started working in clinical practice in 2024, and what I saw with patients confirmed everything I’d been feeling for years.

What We’re Actually Talking About

When I say “seed oils,” I’m referring to a specific group of industrially processed vegetable oils: canola (rapeseed), soybean, corn, sunflower, safflower, cottonseed, grapeseed, and rice bran oil. These are sometimes called “industrial seed oils” because of how they’re made—extracted using chemical solvents, deodorized, bleached, and refined at high temperatures before they ever reach your kitchen.

That process alone is worth pausing on. These oils don’t come from pressing a coconut or an olive; they require significant industrial processing to become something you’d want to put on food. The end product is shelf-stable, cheap to produce, and nearly flavorless—which makes it perfect for the food industry, even if it raises questions about what’s been lost (or created) along the way.

How Did We Get Here?

This is where I try really hard not to blame anyone, because the truth is more complicated than “the food industry tricked us.”

The shift toward seed oils started in the mid-20th century, largely driven by the hypothesis that saturated fat caused heart disease. The American Heart Association began recommending vegetable oils as a replacement for animal fats in the 1960s, and the food industry—which had already developed cheap, scalable ways to produce these oils—was more than happy to meet that demand.

From a systems perspective, it made sense at the time. There was a hypothesis, there were institutions willing to promote it, and there was an industry that could deliver an affordable product. The problem is that the original hypothesis has not held up the way many people assume it has; the research on saturated fat and heart disease is far more nuanced than “saturated fat bad, vegetable oil good.” In the meantime, seed oil consumption in the U.S. has increased dramatically—some estimates suggest a tenfold increase over the last century.

That’s a massive dietary shift in a very short evolutionary window.

The Omega-6 Question

Here’s where the science gets interesting.

Seed oils are exceptionally high in linoleic acid, an omega-6 polyunsaturated fatty acid. Omega-6 isn’t inherently evil—your body needs some of it. The concern is about the ratio of omega-6 to omega-3 fatty acids in the modern diet and what happens when that ratio gets dramatically skewed.

Historically, the human diet likely had an omega-6 to omega-3 ratio somewhere around 1:1 to 4:1. The modern Western diet? Estimates range from 15:1 to 25:1, depending on who you ask. Seed oils are a primary driver of that shift.

From what I’ve seen in the research, excessive linoleic acid consumption appears to promote inflammatory pathways. When linoleic acid is metabolized, it can convert to arachidonic acid, which serves as a precursor for pro-inflammatory compounds called eicosanoids. This doesn’t mean every molecule of omega-6 causes inflammation—it means the dose matters, and we’re getting a lot more of it than our biology seems designed to handle.

There’s also the oxidation issue. Polyunsaturated fats are chemically unstable; they’re more susceptible to oxidation than saturated or monounsaturated fats. When seed oils are heated—especially to the high temperatures used in restaurant fryers and industrial food processing—they produce oxidized lipids and aldehydes, some of which have been linked to oxidative stress and cellular damage in laboratory studies.

I want to be careful here, because the research is still evolving and there are legitimate scientists on multiple sides of this conversation. I’m not going to tell you the science is settled; what I will say is that the pattern is consistent enough that I think it’s worth paying attention to.

What I See Clinically

This is where my experience starts to matter more to me than any single study.

I work with clients and patients on ketogenic, carnivore, and paleo protocols—populations that tend to dramatically reduce seed oil intake as a natural byproduct of eating whole, unprocessed foods. What I see week in and week out is that when people clean up their fat sources—shifting from seed oils to animal fats, butter, ghee, tallow, coconut oil, and olive oil—a cluster of improvements tends to follow.

Skin issues calm down. Joint pain decreases. Digestive complaints improve. Inflammatory markers on bloodwork move in favorable directions. Energy stabilizes.

Am I going to claim that removing seed oils is the sole cause of all those improvements? No. These clients are usually making multiple changes at once—cutting processed food, improving protein intake, addressing blood sugar regulation. Isolating any single variable in real-world clinical practice is genuinely difficult.

What I will say is this: the people who make a point of eliminating seed oils tend to report improvements in inflammatory symptoms faster and more consistently than I’d expect if this variable didn’t matter. In my experience, so far, it’s one of the highest-impact changes a person can make—and it’s one of the ones most people overlook because the oils are so invisible in the food supply.

They’re Everywhere (And That’s the Hard Part)

This is the piece that frustrates me the most, honestly.

Seed oils aren’t just in the obvious places like deep fryers and fast food. They’re in salad dressings, roasted nuts, protein bars, “healthy” snack foods, restaurant meals (even the good restaurants), bread, crackers, sauces, and condiments. If a product comes in a package, there’s a strong chance it contains soybean oil or canola oil—they’re two of the most widely used ingredients in the American food supply.

Reading labels helps, though it can feel overwhelming at first. The ingredients list will tell you exactly which oils are in a product; the front-of-package marketing will not. “Made with olive oil” on the label often means there’s a splash of olive oil alongside a base of canola or soybean oil.

Eating out is trickier. Most restaurants cook with seed oils because they’re cheap and have a high smoke point. Asking your server what oil the kitchen uses is a reasonable question—some places use butter or olive oil, and it’s worth finding those spots.

Practical Swaps

When clients ask me what to cook with instead, I keep it simple:

  • For high heat: beef tallow, ghee, or coconut oil—these are stable saturated fats that handle heat well without oxidizing
  • For medium heat and finishing: extra virgin olive oil, butter, or avocado oil (though avocado oil has its own quality control issues—research from UC Davis has found that a significant percentage of commercial avocado oil is adulterated or oxidized before you even open the bottle)
  • For cold use: extra virgin olive oil is hard to beat

I’m not asking anyone to be perfect about this. Eliminating every trace of seed oil from your diet is nearly impossible unless you prepare every meal at home from whole ingredients. The goal isn’t perfection—it’s awareness. Once you start noticing where these oils show up, you can make informed decisions about which exposures matter most to you.

The Bigger Picture

What bothers me about the seed oil conversation isn’t any single study or any single oil. It’s the pattern.

We took a group of highly processed, industrially produced fats that didn’t exist in the human diet until very recently, made them the foundation of our food supply based on a hypothesis about saturated fat that has not been clearly validated, and now we’re seeing widespread chronic inflammation at population scale. That doesn’t prove causation—I want to be clear about that—but it’s a pattern I don’t think we can afford to ignore. And when I see industry-funded reviews trying to reassure the public that the seed oil concerns are overblown, it tracks with a familiar playbook.

The good news is that this is one of the more actionable changes a person can make. You don’t need a prescription, you don’t need a lab test, and you don’t need to overhaul your entire life. You just need to start paying attention to what’s in the bottle and what’s on the label.

Small changes compound over time. This is one I’d put near the top of the list.

Sources

  • Ramsden CE, et al. “Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968–73).” BMJ, 2016. 10.1136/bmj.i1246
  • Ramsden CE, et al. “Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis.” BMJ, 2013. 10.1136/bmj.e8707

Rance Edwards is a National Board Certified Health and Wellness Coach (NBC-HWC) with over 2,000 clinical hours of experience, specializing in chronic disease management and lifestyle medicine.

If seed oils and inflammation are showing up on your radar and you’d like to talk through what a cleaner approach to dietary fat could look like for your situation, book a free discovery call—no pressure, no pitch.

Photo by Towfiqu Barbhuiya on Pexels