Evidence-based·Last reviewed May 31, 2026·How we grade evidence

Caprylic acid triglycerides

Fatty-acidMCT

Pure C8 (caprylic acid) triglycerides are the single most ketogenic chain in the MCT family — head-to-head studies show C8 produces about 3× the blood ketone rise of C10 and about 4× that of coconut oil at equivalent doses. Use cases are narrow: people on ketogenic diets who want a fast ketone bump, and mild Alzheimer's / MCI patients exploring nutritional ketosis (mostly APOE4-negative). Most other 'brain octane' marketing claims are not supported.

Quick decision guide

May help most

People on a ketogenic diet wanting predictable, fast ketone elevation; APOE4-negative adults with mild Alzheimer's or MCI under clinical supervision exploring nutritional ketosis.

Common dosing range

Start at 1 tsp (5 mL ≈ 5 g). Build to 10–30 g/d split across 2–3 meals. AD trials use 20–30 g/d.

When to expect effects

Ketone rise within 60–90 minutes per dose; clinical-trial endpoints at 1–3 months.

Watch out for

GI side effects (cramping, loose stools, nausea) scale with single-dose size — start small and titrate up.

Evidence snapshot

Acute ketone elevationStrong

Cognition in APOE4-negative mild ADEmerging

Cognition in healthy adultsLow

Athletic performance / enduranceLow

Weight loss (over mixed MCT or coconut)Low (no head-to-head)

What is it

Caprylic acid triglycerides are esters of glycerol with three caprylic acid (C8) molecules. They are a medium-chain triglyceride (MCT) component often sold as 'Brain Octane' or pure C8 MCT oil.

Is it worth it for you?

Use this as a quick fit check, not a diagnosis.

Worth considering if…

You're on a strict ketogenic diet and want the fastest, most predictable ketone bump per gram of MCT

You have mild Alzheimer's or MCI, you're APOE4-negative, and your neurologist supports a structured nutritional-ketosis trial

You're using MCT around exercise or fasting on a keto diet and want to extend ketosis

You found mixed C8/C10 MCT gave you GI side effects and want to try a purer C8 product (sometimes better tolerated per gram)

Probably skip if…

You expect 'brain octane' to make you smarter — there's no evidence in healthy adults

You're APOE4-positive with Alzheimer's — Henderson 2009 showed no cognitive benefit in carriers

You're on a high-carb diet and want C8 for 'brain energy' — sustained insulin blunts the ketone response; you'll get little of the supposed benefit

You have IBS, IBD, or sensitive bowels — diarrhea is the most common reason people stop

Price matters and you'd get equivalent value from mixed C8/C10 MCT (60:40) — pure C8 typically costs 2–3× as much per gram

You're substituting C8 MCT for healthy unsaturated fats (olive oil, fish oil) — that raises LDL cholesterol

Evidence at a glance

Goal	Effect	Best fit	Time
Acute ketone elevation Strong Evidence	Plasma β-hydroxybutyrate rises ~0.3–0.6 mmol/L within 60–90 min of a 15–20 g C8 dose; 3× the response of C10, ~4× that of coconut oil	Adults on a ketogenic diet wanting predictable, fast ketone elevation	60–90 min per dose
Cognition in APOE4-negative mild Alzheimer's / MCI Limited Evidence	~3–5 point ADAS-Cog improvement in APOE4-negative mild AD over 45–90 days; null in APOE4 carriers	APOE4-negative adults with mild AD or MCI under neurologist supervision	45–90 days in trials
Cognition / focus in healthy adults Mixed Evidence	No reliable cognitive benefit demonstrated in healthy adults	Not applicable — no evidence supports this use	Not established
Athletic performance / endurance Mixed Evidence	No reliable performance benefit in controlled trials	Possibly keto-adapted endurance athletes — evidence is still weak	Not established

Acute ketone elevation

Strong Evidence

Effect: Plasma β-hydroxybutyrate rises ~0.3–0.6 mmol/L within 60–90 min of a 15–20 g C8 dose; 3× the response of C10, ~4× that of coconut oil
Best fit: Adults on a ketogenic diet wanting predictable, fast ketone elevation
Time: 60–90 min per dose

Cognition in APOE4-negative mild Alzheimer's / MCI

Limited Evidence

Effect: ~3–5 point ADAS-Cog improvement in APOE4-negative mild AD over 45–90 days; null in APOE4 carriers
Best fit: APOE4-negative adults with mild AD or MCI under neurologist supervision
Time: 45–90 days in trials

Cognition / focus in healthy adults

Mixed Evidence

Effect: No reliable cognitive benefit demonstrated in healthy adults
Best fit: Not applicable — no evidence supports this use
Time: Not established

Athletic performance / endurance

Mixed Evidence

Effect: No reliable performance benefit in controlled trials
Best fit: Possibly keto-adapted endurance athletes — evidence is still weak
Time: Not established

Evidence for 4 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Acute ketone elevation

Biomarker support

Strong Evidence

Pure C8 (tricaprylin) is the most ketogenic MCT chain. Vandenberghe 2017's head-to-head trial in healthy adults found C8 produced a peak plasma beta-hydroxybutyrate around 0.5 mmol/L within 90 minutes of a 20 g dose — about 3× the response of pure C10, 2× the response of mixed C8/C10 (60:40), and 4× the response of coconut oil at the same gram dose. The ketone rise is reliable and dose-dependent, and lasts 2–4 hours. This is a biochemical effect, not a clinical claim by itself.

Effect size

Plasma β-hydroxybutyrate rises ~0.3–0.6 mmol/L within 60–90 min of a 15–20 g C8 dose; 3× the response of C10, ~4× that of coconut oil

Time to effect

60–90 min per dose

Best fit

Adults on a ketogenic diet wanting predictable, fast ketone elevation

Less likely

Adults on a high-carb diet — sustained insulin blunts the ketogenic response

Bottom line: Real, reliable, fastest ketone bump per gram in the MCT family. Whether ketones help your specific goal is a separate question.

SourceVandenberghe et al., 2017 — PMC — Current Developments in Nutrition Vandenberghe et al., 2019 — PubMed — Nutrition Research

Cognition in APOE4-negative mild Alzheimer's / MCI

Disease adjunct

Limited Evidence

Henderson 2009 (AC-1202, the medical-food form of C8 triglycerides) showed a ~4.77-point ADAS-Cog improvement at day 45 (p=0.0005) and 3.36 at day 90 in APOE4-negative patients with mild-moderate Alzheimer's. APOE4-positive carriers showed no benefit. Norgren 2020 (15 g BID × 8 weeks) and Vandenberghe 2019 (30 g/d × 1 month) replicated the ketone-elevation finding and saw subgroup-consistent (but not overall) cognitive signals. Croteau 2018 showed PET brain ketone uptake compensates for the AD-typical brain-glucose hypometabolism. The most reliable predictor is APOE4 status; effect sizes are modest, and this is not a cure.

Effect size

~3–5 point ADAS-Cog improvement in APOE4-negative mild AD over 45–90 days; null in APOE4 carriers

Time to effect

45–90 days in trials

Best fit

APOE4-negative adults with mild AD or MCI under neurologist supervision

Less likely

APOE4-positive AD, late-stage dementia, healthy adults

Bottom line: Worth discussing with the neurologist if APOE4-negative and mild stage; skip if APOE4-positive.

Evidence is mixed

Henderson 2009 was sponsored by the AC-1202 maker. Subsequent independent trials (Norgren 2020) show weaker overall effects; APOE4 stratification consistently predicts response.

SourceHenderson et al., 2009 — PubMed — Nutrition & Metabolism· conflicting Norgren et al., 2020 — PubMed — Journal of Internal Medicine· conflicting

SourceHenderson et al., 2009 — PubMed — Nutrition & Metabolism Vandenberghe et al., 2019 — PubMed — Nutrition Research Norgren et al., 2020 — PubMed — Journal of Internal Medicine Croteau et al., 2018 — PubMed — Journal of Alzheimer's Disease

Cognition / focus in healthy adults

Mechanism only

Mixed Evidence

Despite extensive 'brain octane' marketing, there are essentially no controlled trials showing cognitive benefit in healthy adults from C8 MCT. The mechanism (ketone elevation) is well-established; the clinical claim (better focus, faster thinking) is not. Subjective reports of 'clean energy' are common but don't translate into measurable cognitive performance gains in controlled studies.

Effect size

No reliable cognitive benefit demonstrated in healthy adults

Time to effect

Not established

Best fit

Not applicable — no evidence supports this use

Less likely

Anyone hoping C8 will replace sleep, caffeine, or training as a performance edge

Bottom line: Don't pay a premium for 'cognitive enhancement' claims. The brain-energy gap C8 corrects is specific to AD.

SourceVandenberghe et al., 2017 — PMC — Current Developments in Nutrition

Athletic performance / endurance

Mechanism only

Mixed Evidence

C8 MCT is sometimes marketed for endurance athletes on the premise that ketones spare glycogen. Trials testing time-to-exhaustion, peak power, or recovery outcomes are small and inconsistent. GI side effects from a pre-exercise C8 dose often hurt performance more than the ketones help.

Effect size

No reliable performance benefit in controlled trials

Time to effect

Not established

Best fit

Possibly keto-adapted endurance athletes — evidence is still weak

Less likely

Athletes on a high-carb diet for whom GI distress would impair performance

Bottom line: Don't rely on C8 as a performance edge. If you tolerate it on a keto diet, it's fine fuel; otherwise skip.

SourceParrish, 2017 — Practical Gastroenterology

How it works

Unlike long-chain triglycerides, C8 caprylic triglycerides are hydrolyzed quickly, absorbed via the portal vein, and shuttled to the liver where they are rapidly oxidized to acetyl-CoA. A portion is converted to ketone bodies (beta-hydroxybutyrate), which can fuel the brain and muscle independent of insulin. C8 is the most ketogenic of the medium-chain fatty acids.

How to take it

1. Typical dose

• Start: 1 tsp (5 mL ≈ 5 g) with food for 3–5 days • Build to 10–30 g/d split across 2–3 meals as tolerated • AD / MCI trial doses: 20–30 g/d (the Vandenberghe / Henderson protocols) • Pure C8 has slightly more GI tolerance than mixed C8/C10 in some users — but single-dose size matters more than chain length

2. Higher studied dose

30 g/d (1 oz / 2 Tbsp) is the upper end used in cognitive-decline trials, typically split into 2–3 doses. Doses above 50 g in a single sitting reliably cause GI upset in most people.

3. Timing

Take with food. Common pairings: coffee (the 'bulletproof' staple), smoothies, salad dressing, stirred into oatmeal or yogurt. Avoid empty-stomach use until tolerance is established. Pre-workout dosing risks GI distress.

4. With food

Yes — always with food, especially while titrating up.

5. Split dosing

Split across 2–3 meals rather than a single large dose. GI side effects scale with single-dose size; total daily amount matters less.

6. How long to try

Ketone elevation is immediate (1–2 hr). Cognitive trial endpoints in AD/MCI run 1–3 months. Body-composition or 'mental clarity' effects in healthy adults are not established, so don't commit to long-term use without a clear benefit you can track.

What to track

GI side effects — cramping, loose stools, nausea (back off the dose, not the frequency)

Blood ketones (β-hydroxybutyrate) if on a keto diet and verifying response

Cognitive measures (paper-pencil or app-based) if using for AD/MCI under clinician oversight

Lipid panel (LDL-C) if you're substituting C8 MCT for unsaturated fats long-term

Bottom line: Start at 1 tsp with food. Build slowly to 10–30 g/d split. Stop if GI side effects don't resolve within a week.

5 commercial forms

Compare the main delivery options and what they’re best suited for.

Pure C8 / tricaprylin (this form)

Strongest ketone bump

100% caprylic acid triglycerides. Produces ~3× the blood ketone response of pure C10 and ~4× that of coconut oil at equivalent gram doses. Most expensive MCT format per gram.

Highest β-hydroxybutyrate response per gram in the MCT family.

Mixed C8/C10 (60:40 to 80:20) MCT oil

Most common

The workhorse format. Mid-priced and used in most weight/body-comp MCT trials. Ketogenic effect is moderate — about half the per-gram ketone response of pure C8, but cheaper.

Moderate ketogenic effect; the standard for general MCT use.

Caprylidene (AC-1202 / Axona, medical food)

Medical food for AD

Prescription-style medical food specifically labeled for mild-moderate Alzheimer's. Same active molecule as supplement-grade C8 MCT but sold through clinician channels with a formal AD indication.

Functionally equivalent to high-quality C8 MCT oil.

MCT powder (often C8-only or mostly C8)

Convenient mixing

Spray-dried MCT on a carrier (acacia fiber or maltodextrin). Mixes into drinks more easily than oil. Acacia-carrier versions are appropriate for keto users; maltodextrin spikes blood glucose and defeats the purpose.

Slightly slower absorption than liquid MCT; carrier ingredient matters.

Coconut oil (~6% C8)

Whole food, weakest

About 60% MCTs by content but mostly C12 (lauric acid, which behaves metabolically more like a long-chain fat). Only ~6% C8 and ~6% C10. Produces a much smaller ketone bump than C8 MCT oil and shouldn't be relied on for therapeutic nutritional ketosis.

~4× lower ketone response than pure C8 at the same gram dose.

Safety

Know the common side effects, key cautions, and who should avoid it.

Common side effects

loose stools or diarrheaabdominal crampingnauseaburpingbloating

Serious risks

Severe GI upset (watery diarrhea, vomiting) with rapid dose escalation or doses above ~50 g in a single sitting. Almost always self-limiting after dose reduction.
SourceParrish, 2017 — Practical Gastroenterology
LDL cholesterol can rise when C8 MCT replaces unsaturated fats (olive oil, fish oil, canola). Keep C8 as a substitution for less-healthy fats, not for monounsaturates.
SourceWatanabe & Tsujino, 2022 — PubMed — Journal of Nutrition
Theoretical risk of inducing ketoacidosis in poorly-controlled type 1 diabetes — caution in insulin-dependent diabetes on ketogenic regimens, only under diabetologist oversight.
SourceParrish, 2017 — Practical Gastroenterology

Who should avoid it

People with hepatic encephalopathy or advanced cirrhosis — MCTs are processed primarily by the liver; discuss with hepatologist.
SourceParrish, 2017 — Practical Gastroenterology
People with type 1 diabetes on insulin — risk of unexpected ketosis and need for insulin adjustment; only with diabetologist supervision.
SourceParrish, 2017 — Practical Gastroenterology
People with severe IBS, IBD flare, or active GI inflammation — symptoms commonly worsen with even small MCT doses.
SourceParrish, 2017 — Practical Gastroenterology
People with severe pancreatitis or chronic pancreatitis flares — fat tolerance is reduced.

Pregnancy & breastfeeding

C8 MCT is well-tolerated as a food fat in moderate amounts during pregnancy and breastfeeding. It's used clinically in infant formulas (smaller dose) and in malabsorption during pregnancy. Higher-dose ketogenic-style use during pregnancy hasn't been systematically studied — stay at food-level amounts unless you're under medical supervision.

SourceParrish, 2017 — Practical Gastroenterology

Bottom line: Safe in moderate amounts for most people; GI tolerance is the practical limit. Don't ramp fast.

Interactions

insulin and sulfonylureas (in diabetes)Moderate

Adding C8 MCT to a ketogenic or carb-restricted diet can amplify the ketogenic effect and require insulin/sulfonylurea dose reduction. Monitor glucose closely.

SourceParrish, 2017 — Practical Gastroenterology

lipid-lowering medications (statins, fibrates)Minor

If C8 MCT substitutes for unsaturated fats it may modestly raise LDL — check follow-up lipid panel and discuss with your prescriber.

SourceWatanabe & Tsujino, 2022 — PubMed — Journal of Nutrition

valproic acid (Depakote)Minor

Theoretical interaction via shared β-oxidation pathways; the combination is used in some ketogenic-diet epilepsy programs but warrants clinician awareness.

anti-emetics (when starting at high doses)Minor

Not a true drug interaction; just a flag that GI side effects from high-dose C8 may confound assessment of new GI symptoms.

Food sources

Food	Amount	%DV
Pure C8 MCT oil	1 Tbsp / 14 mL (~13 g caprylic triglycerides)	—
Mixed C8/C10 MCT oil	1 Tbsp / 14 mL (~7–11 g C8 depending on ratio)	—
Coconut oil	1 Tbsp / 14 g (~0.8 g caprylic acid)	—
Coconut milk, canned	½ cup (~0.5 g caprylic acid)	—
Whole milk (cow)	1 cup (~0.07 g caprylic acid)	—
Butter	1 Tbsp (~0.05 g caprylic acid)	—

Pure C8 MCT oil

Amount: 1 Tbsp / 14 mL (~13 g caprylic triglycerides)
%DV: —

Mixed C8/C10 MCT oil

Amount: 1 Tbsp / 14 mL (~7–11 g C8 depending on ratio)
%DV: —

Coconut oil

Amount: 1 Tbsp / 14 g (~0.8 g caprylic acid)
%DV: —

Coconut milk, canned

Amount: ½ cup (~0.5 g caprylic acid)
%DV: —

Whole milk (cow)

Amount: 1 cup (~0.07 g caprylic acid)
%DV: —

Butter

Amount: 1 Tbsp (~0.05 g caprylic acid)
%DV: —

Choosing a product

What to look for on the label — and what to be skeptical of.

Look for…

100% caprylic acid (C8) listed as the only ingredient — not 'mixed MCT,' 'C8/C10,' or 'MCT from coconut'

Glass bottle and dark storage — fatty oils oxidize over time

Coconut-derived (vs palm) if sustainability matters; both are equivalent biochemically

Third-party tested (USP, NSF, ConsumerLab) — independent testing has flagged products with much less C8 than label claims

Country of origin disclosed; manufacturer reachable

No 'proprietary blend' language hiding the actual C8 content

Be skeptical of…

'Brain Octane' / 'smart drug' / 'cognitive enhancer' marketing for healthy adults — Henderson's effect was in APOE4-negative AD, not in healthy brains

'Better than coffee for focus' / 'replaces caffeine' — no controlled trials support this

'Burns fat for fuel' as a weight-loss claim — the body-comp evidence base is for mixed MCT, not C8 specifically, and effects are small

'Vegan keto super-fuel' on coconut oil products — coconut oil is mostly C12 (lauric acid), not C8, and produces a much smaller ketone bump

'C8/C10 60:40 MCT oil' sold as 'pure C8' — different product

'No GI side effects' claims at high doses — false; all MCTs cause GI upset above tolerance

Frequently asked questions

Is C8 better than regular coconut oil?⌄

It produces a stronger ketone response per gram. Coconut oil is mostly lauric acid (C12), which is less ketogenic.

Why am I getting diarrhea?⌄

Common with rapid escalation. Start at 1 teaspoon with food and increase over a week.

References by claim

Acute ketone elevation

Vandenberghe et al., 2017 — PMC — Current Developments in Nutrition (2017) link

Vandenberghe et al., 2019 — PubMed — Nutrition Research (2019) link

Cognition in APOE4-negative mild Alzheimer's / MCI

Henderson et al., 2009 — PubMed — Nutrition & Metabolism (2009) link

Norgren et al., 2020 — PubMed — Journal of Internal Medicine (2020) link

Croteau et al., 2018 — PubMed — Journal of Alzheimer's Disease (2018) link

Athletic performance / endurance

Parrish, 2017 — Practical Gastroenterology (2017) link

Safety

Watanabe & Tsujino, 2022 — PubMed — Journal of Nutrition (2022) link

Other references

Caprylic acid triglycerides on NIH DSLD — NIH Dietary Supplement Label Database link

Track Caprylic acid triglycerides with Pilora

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Evidence-based·Last reviewed May 31, 2026·Evidence current as of May 31, 2026·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.