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James H. O'Keefe MD's avatar

Great question Karin — here is what CHAT GPT says

Big picture first

• Yes, MCTs (medium-chain triglycerides) are absorbed directly into the portal vein and go straight to the liver, unlike long-chain fats that get packaged into chylomicrons.

• Because of that, they tend to have less post-prandial lipemia and less immediate impact on LDL than saturated long-chain fats.

• But… “less” does not mean “none,” particularly in APOE4 carriers.

APOE4 + MCTs

• APOE4 individuals are more sensitive to saturated fat, even shorter-chain ones.

• Several lipidologists (and plenty of N=1 data) have seen LDL-C and ApoB rise in some APOE4 carriers using MCT oil or powder.

• The liver can convert excess MCTs into acetyl-CoA → cholesterol and VLDL, especially if total caloric intake is high or insulin resistance is present.

C8 vs C10 vs “generic” MCT

This is where nuance matters:

C8 (caprylic acid)

• Most ketogenic

• Rapidly oxidized

• Least likely of the MCTs to raise LDL

• Shorter half-life, less incorporation into lipoproteins

C10 (capric acid)

• Still MCT, but behaves a bit more like long-chain fat

• More likely to raise LDL than C8

C12 (lauric acid)

• Not really an MCT physiologically

• Clearly raises LDL (especially in APOE4)

👉 If an APOE4 patient is going to use MCT at all, C8-only is the safest choice.

MCT oil vs MCT powder

• Powder = MCT oil + carrier (usually acacia fiber or tapioca-derived starch)

• Lipid effects come from the fat itself, not the form

• Powder may blunt absorption slightly, but does not eliminate LDL effects

Practical advice I usually give

For APOE4 carriers:

• ✅ Prefer C8-only

• ✅ Keep dose low (e.g., 5–10 g/day, not 20–30 g)

• ✅ Use in a metabolically healthy context (exercise, low refined carbs)

• ❌ Avoid if LDL-C, ApoB, or LDL-P rise meaningfully

• 📊 Check ApoB after 6–8 weeks — that’s the arbiter

Bottom line

• Your instinct is right: portal vein transport does reduce—but does not eliminate—LDL effects

• C8 is “less bad,” not “neutral,” in APOE4

• In APOE4 carriers chasing metabolic or cognitive benefits, I treat MCTs as a trial with labs, not a free pass

Wayne Osborn's avatar

Excellent! My morning glucose has been in the low 90s. I asked AI about it, and it said yeah, that's common in keto and fasting and nothing to worry about - just your body adjusting. I had been thinking of adding MCTs again... and also saffron. You gave me the go-ahead! Good story!

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