Peter Attia, M.D., with Layne Norton, Ph.D., Breaks Down the Seed Oil Debate: Are They Actually Hurting Your Health?

Seed oils are suddenly everywhere in health debates—blamed for inflammation, heart disease, and “modern illness.” But are they actually harmful… or just misunderstood?

👉 Watch the full conversation on YouTube here to hear Peter Attia, M.D., and Layne Norton, Ph.D., walk through the real science behind seed oils, cholesterol, and cardiovascular risk.

Who’s speaking?

• Peter Attia, M.D. is a physician known for deep dives into longevity, cardiovascular disease, and metabolic health.

• Layne Norton, Ph.D. is a PhD in nutritional sciences who specializes in metabolism, fat loss, and evidence-based nutrition—especially where popular narratives conflict with data.

The Seed Oil Debate, Explained Simply

The internet claim goes like this:

“Seed oils are uniquely toxic, inflammatory, and responsible for modern heart disease.”

The reality, according to the best available evidence, is far more nuanced.

Peter and Layne walk through decades of human trials, genetics, and mechanisms—and the big takeaway is this:

Seed oils are not uniquely harmful when compared to other fats.
In fact, when they replace saturated fat calorie-for-calorie, cardiovascular risk usually goes down, not up.

But there are reasons people are confused—and some concerns aren’t completely wrong.

Why Old Studies Made Seed Oils Look Dangerous (But Aren’t the Smoking Gun)

Several classic studies often cited by anti–seed oil advocates showed worse outcomes when saturated fat was replaced with vegetable oils.

The problem?
Those studies used margarine loaded with trans fats—sometimes 25–40% trans fat by content.

We now know:

• Trans fats are far more harmful than saturated fat

• They are unequivocally atherogenic

• They are now banned for a reason

👉 When studies remove trans fat confounding, the apparent harm of seed oils disappears—and often reverses.

The LDL & Cholesterol Piece Most People Miss

Here’s the part that rarely shows up on social media:

• LDL particles (ApoB-containing particles) are a causal driver of atherosclerosis
  

• This is supported by:

  • Human randomized trials

  • Statin trials

  • Mendelian randomization (lifelong genetic “experiments”)

Across all methods:

Lower LDL exposure over time = lower heart disease risk

And crucially:

• Replacing saturated fat with polyunsaturated fat (including seed oils) lowers LDL

• This effect is consistent and dose-dependent

Even if seed-oil–derived LDL particles are slightly more prone to oxidation, far fewer particles enter artery walls in the first place, which matters far more.

“But Aren’t Seed Oils Inflammatory?”

This is one of the biggest myths addressed.

Yes, seed oils contain linoleic acid, which can theoretically convert to inflammatory molecules.

But in real humans:

• Higher linoleic acid intake is associated with lower cardiovascular risk

• Tissue levels of linoleic acid correlate with better, not worse, outcomes

• Conversion to inflammatory arachidonic acid is tightly regulated—not runaway

Oxidized LDL mostly forms inside artery walls, not floating around your blood.
The biggest driver of oxidation is how much LDL enters and stays there, not whether you used canola oil on a salad.

What About Processing, Hexane, and “Industrial Oils”?

Another common concern: chemical extraction and processing.

What the data actually show:

• Residual hexane levels are extremely low (parts per million or less)

• You’d need to consume thousands of kilograms of oil at once to approach toxicity

• Refining actually reduces oxidation products, not increases them

• These compounds do not bioaccumulate

This doesn’t mean ultra-processed foods are healthy—it means seed oils themselves aren’t the villain.

The Real-World Confounder No One Talks About

Seed oils show up most often in:

• Chips

• Fries

• Ultra-processed foods

• Junk sauces and dressings

So when people remove seed oils and “feel better,” it’s often because they:

• Ate fewer calories

• Ate less junk food

• Improved overall diet quality

That’s a win—but it doesn’t prove seed oils were toxic.

Dr. Bones Take 🦴

While this topic is messy, the advice is still clear:

• Get your labs done (LDL, ApoB, cholesterol markers matter)

• Watch your cholesterol and heart risk over time

• Keep saturated fat intake reasonable to protect cardiovascular health

• And out of an abundance of caution, avoiding seed oils isn’t a bad idea—but it’s not mandatory

• When possible, opt for olive oil or avocado oil, especially for home cooking

• Seed oils are often used in highly processed foods, which should be avoided in general 

ACTIONABLE TAKEAWAYS (What You Should Actually Do)

1. Prioritize LDL & ApoB, not food fear
If you care about heart health, tracking LDL and ApoB matters more than obsessing over oil types.

2. Don’t swap seed oils for unlimited butter or tallow
Replacing seed oils with saturated fat often worsens cholesterol—even if it “feels ancestral.”

3. Cooking matters more than the oil label
Repeatedly reheated oils (restaurant fryers) are worse than occasional home use—regardless of oil type.

4. Olive oil & avocado oil are safe default choices
They’re stable, heart-friendly, and easy to use—but not magical.

5. Focus on big levers first
Calories, activity, fiber intake, protein, and strength matter far more than seed oil minutiae.

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