Not All Seed Oils Are Toxic

Understanding the Difference Between Ultra-Processed Seed Oils and Cold-Pressed Seed Oils

If you’ve spent time in the ancestral health or real-food world, you’ve probably heard that “seed oils are toxic.” It’s a claim that’s become almost gospel online. And while there’s plenty of truth behind the warning, it’s also missing something important: not all seed oils are created equal.

The problem isn’t necessarily the seed. It’s what modern processing does to it.

When you get all your information from short social-media clips or Instagram posts, you only get the surface-level story. The nuance gets lost, and so do the real differences between ultra-processed and cold-pressed oils.

How Ultra-Processed Seed Oils Are Made

Most of the seed oils you’ll find in packaged foods, restaurant fryers, and grocery-store bottles are ultra-processed. Oils like canola, soybean, corn, cottonseed, and safflower are extracted in massive industrial facilities built for efficiency, not nourishment.

Here’s what that process looks like. The seeds are heated and crushed under high pressure, then treated with a chemical solvent, usually hexane, to pull out every last drop of oil. After that, the oil is refined, bleached, and deodorized at very high temperatures, sometimes reaching 450 to 500°F during the final deodorization stage.

Hexane, a solvent derived from petroleum, is classified as a neurotoxin in humans and animals. Manufacturers claim it’s removed before bottling, but its use in food processing raises valid concerns. Even if residues are minimal, the fact that your cooking oil had to be chemically stripped and deodorized at extreme temperatures says enough. That’s not real food.

By the end of this refining process, nearly all of the oil’s natural antioxidants, vitamins, and flavor compounds are gone. What’s left is a neutral, shelf-stable liquid that looks clean but is chemically fragile.

These oils are high in polyunsaturated omega-6 fatty acids (mainly linoleic acid), which oxidize easily when exposed to heat, air, and light. That oxidation produces reactive compounds called aldehydes, which can damage cells and tissues when consumed regularly, especially from fried or reheated oils.

So yes, the concern is real. Ultra-processed seed oils are not the same as natural fats like tallow, butter, or olive oil.

Traditional Cold-Pressed Seed Oils

Not every oil that comes from a seed deserves the same bad reputation.

Some seed oils, when made the traditional way (cold-pressed and unrefined), can be stable, flavorful, and rich in beneficial compounds. Think of oils like sesame, and peanut oil and black cumin.

The key difference lies in how they’re made.

Cold-pressed oils are extracted mechanically, without solvents or high heat. That means no chemical refining, no bleaching or deodorizing, and minimal oxidation. These oils retain natural antioxidants such as vitamin E, sesamol, or resveratrol, depending on the seed.

They’ve been part of traditional diets for centuries—sesame oil in East Asia, peanut oil in West Africa, pumpkin seed oil in Central Europe. Each has its own distinct flavor and nutrient profile. They’re aromatic, nutrient-rich, and used sparingly for flavor, not as bulk industrial ingredients.

Some of these oils even contain compounds that protect the fat from oxidation. For example, sesame oil contains sesamol and sesamin, two natural antioxidants that make it remarkably stable compared to modern refined oils.

It’s About Processing, Not Paranoia

When people say “seed oils are toxic,” they’re referring to the industrial versions refined with chemicals, heated repeatedly, and used in deep fryers or processed foods. They are a modern invention, not a traditional food.

Cold-pressed or expeller-pressed seed oils, on the other hand, are much closer to whole foods. They can be a healthy addition when used as finishing oils, in low-heat cooking, and in small amounts. 

Final Thoughts

Seed oils exist on a spectrum.

At one end are the highly refined industrial oils, which are cheap, overused, and stripped of life. At the other are the cold-pressed, minimally processed oils that still carry the character of the plant they came from.

That’s being said, do we think that you should be cooking all your meals with cold-pressed seed oils? No. 

Humans are suppose to get most of our nutrients from animals. Beef tallow, butter or ghee should be what you cook most of your meals with. 

Seed oils aren’t all equal, but they also aren’t essential. Animal fats are.