Subject: 🧈The fat in butter that reverses artery plaque
From: Seed Oil Scout <[email-masked]>
To: [email-masked]
Date: Tue, 12 May 2026 13:53:01 +0000

A study found it didn't just stop atherosclerosis. It reversed it.  

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The Fat in Butter that Reverses Artery Plaque
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For decades, you were told to swap butter for margarine to protect your heart. Butter clogs arteries. Margarine saves them. That was the pitch. But a study published in Atherosclerosis found something the margarine lobby never mentioned: a naturally occurring fat in butter and beef doesn't just slow artery plaque. It reverses it.

 

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The Study
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Researchers at Trinity College Dublin took mice genetically engineered to develop atherosclerosis (ApoE-knockout mice) and fed them a high-cholesterol diet for eight weeks to build up artery plaque. Then they split the mice into two groups: one continued on the same diet, the other got the same diet plus 1% conjugated linoleic acid (CLA).

After eight more weeks, the CLA group showed almost complete resolution of their pre-existing arterial lesions. Not a slowdown. Not a pause. Near-total reversal.

The mechanism? CLA reduced macrophage buildup in artery walls, triggered programmed cell death in damaged plaque tissue, and activated PPARα and PPARγ receptors, both of which suppress chronic inflammation. It also inhibited platelet deposits on artery walls, a key driver of clot formation.

(Toomey et al., 2006, Atherosclerosis - PubMed ( https://pubmed.ncbi.nlm.nih.gov/16182300 ))

 

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What is CLA?
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Conjugated linoleic acid is a naturally occurring trans fat (the good kind) produced in the stomachs of ruminant animals like cows, sheep, and goats. It ends up in their milk and meat.

Here's the twist: CLA is technically a form of linoleic acid, the same omega-6 fatty acid found in seed oils. But its molecular geometry is completely different. The "conjugated" double bonds give it the opposite biological effect. Industrial linoleic acid from soybean and canola oil drives inflammation. CLA from dairy and beef fights it.

 

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Where to find it
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CLA content varies dramatically depending on what the animal ate.

* Grass-fed butter: 21-24 mg CLA per gram of fat
* Conventional butter: 4-7 mg CLA per gram of fat
* Grass-fed beef: 3-5x more CLA than grain-fed
* Grass-fed cheese, yogurt, whole milk: all meaningful sources
* Lamb: consistently high in CLA regardless of feed

Grass-fed dairy has roughly 3 to 5 times more CLA than conventional. The reason is simple: ruminants eating fresh pasture produce more CLA in their gut during digestion. Grain-fed animals produce less.

 

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The irony
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The dietary guidelines that told Americans to replace butter with margarine (hydrogenated seed oils) effectively removed the single richest dietary source of CLA from the American diet. They replaced a fat that reverses artery damage with a fat that promotes inflammation.

This matters for the ongoing statin conversation too. If a naturally occurring dairy fat can activate the same anti-inflammatory pathways (PPARs) that pharmaceutical companies spend billions targeting, the question becomes: why isn't anyone studying this in large-scale human trials?

 

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Important caveats
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This was a mouse study, not a human trial. ApoE-knockout mice develop atherosclerosis far faster and differently than humans. CLA supplements (synthetic versions) have shown mixed results in human studies, and some CLA isomers may behave differently than the natural blend found in dairy fat.

The most consistent benefits come from the cis-9, trans-11 isomer, which is the dominant form in grass-fed dairy.

The takeaway isn't "CLA cures heart disease." It's that the foods you were told to avoid contain compounds with profound anti-inflammatory and anti-atherosclerotic properties. And the foods you were told to eat instead contain none of them.

 

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Bottom Line
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* CLA from dairy fat reversed pre-existing artery plaque in atherosclerosis-prone mice
* It works by reducing inflammation, clearing damaged cells, and activating PPAR receptors
* Grass-fed butter has 3-5x more CLA than conventional butter
* Industrial linoleic acid (seed oils) and conjugated linoleic acid (dairy) have opposite effects despite sharing a name
* Replacing butter with margarine removed the best dietary source of CLA from the American diet

 

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