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★ TIER B+ — STRONG & EMERGING 6 Clinical Trials 100+ Publications Cardiovascular · Metabolic · Longevity

Fatty15 (C15:0 — Pentadecanoic Acid)

The first essential fatty acid identified in nearly a century. Six clinical trials, 100+ peer-reviewed publications, and a head-to-head comparison with rapamycin showing equivalent — and often superior — activity across 12 human cell systems.

Evidence Strength
B+
36
Clinically Relevant Cell Activities
6
Published Clinical Trials
100+
Peer-Reviewed Publications
−29 U/L
ALT Reduction (RCT, threshold group)
33%
Liver Fat Reduction — TANGO RCT
14,000+
Cohort — Lower C15:0 linked to higher 14-yr mortality
Disclosure — Conflict of Interest: The primary researcher behind most C15:0 publications, Dr. Stephanie Venn-Watson, is also co-founder of Fatty15. EBL notes this transparently. The science is independently compelling, but independent replication from unaffiliated labs is still limited. This is factored into the B+ (not A) grade. We cite this not to dismiss the evidence — which withstands scrutiny — but because our standards require disclosure of funding and authorship conflicts.

Clinical Trials on Record

All controlled studies to date — chronological order

TrialDesignNDose / DurationKey Finding
Stallings et al. — Pharmacokinetics Controlled, human Single oral dose C15:0 Every 100 mg C15:0 raises circulating levels by ~1 µg/mL; confirmed predictable dose-response bioavailability
Venn-Watson et al. — Navy dolphin longevity study Longitudinal, controlled ~50 dolphins Dietary C15:0 supplementation Higher C15:0 correlated with slower aging rate biomarkers, higher hemoglobin, improved metabolic indices in long-lived mammals
TANGO RCT — Am J Clin Nutr, 2024 Mar;119(3):788–799 Randomized, controlled, 3-arm ~90 females with NAFLD C15:0 + Med diet vs. Med diet alone vs. control · 12 weeks C15:0 arm: −33% liver fat, lower LDL-C, favorable gut microbiome shift (Bifidobacterium adolescentis ↑) — above and beyond diet alone
Vascular health pilot — Human, controlled Controlled Small cohort Daily C15:0 · 12 weeks Improvements in vascular health markers and mood indices observed
Robinson / Schwimmer RCT — J Nutrition, 2024 (NCT04947176) Double-blind, randomized, placebo-controlled 30 (20 treatment, 10 placebo) 200 mg/day fatty15 vs. rice flour · 12 weeks Threshold group (C15:0 >5 µg/mL): ALT −29 U/L, AST −6 U/L, hemoglobin +0.6 g/dL. No adverse events. 2/3 of participants at baseline met criteria for C15:0 deficiency.
LDL RCT — Adult women with high BMI Randomized, controlled Pure C15:0 · 12 weeks Significant LDL-cholesterol reduction in women with elevated BMI who reached sufficient C15:0 levels

Mechanism — Why C15:0 Is Structurally Different

Odd-chain saturated fatty acids behave fundamentally differently from even-chain and unsaturated fats

Cell Membrane Stabilization

C15:0 integrates into cell membranes as a structurally stable, odd-chain saturated fatty acid. Unlike even-chain saturated fats (which pack too rigidly) or unsaturated fats (which are peroxidation-prone), C15:0 occupies a mechanical sweet spot — reducing membrane fragility and ferroptosis risk. Studies demonstrate 80% improvement in cellular stability with C15:0 supplementation.

AMPK Activation / mTOR Inhibition

C15:0 activates AMPK — the cellular energy sensor and metabolic master switch — and inhibits mTOR, the primary driver of cellular aging and senescence. These are the same two pathways targeted by metformin (AMPK) and rapamycin (mTOR) respectively. C15:0 achieves both simultaneously at physiologically relevant concentrations.

Mitochondrial Complex II Repair

C15:0 directly rescues mitochondrial function at Complex II of the electron transport chain by increasing succinate production. Mitochondrial dysfunction is a primary hallmark of aging — and Complex II is rarely targeted by other longevity compounds. This is a mechanistically distinct contribution to the longevity stack.

PPAR α/δ Dual Agonist

As a dual partial PPAR alpha/delta agonist, C15:0 activates metabolic regulators that govern fat burning, inflammation, liver function, and cardiovascular homeostasis. This mechanism underpins its demonstrated activity in NAFLD (TANGO trial) and cardiometabolic endpoints seen across cohort and clinical studies.

Ferroptosis Resistance

Ferroptosis is iron-dependent lipid peroxidation cell death — a key driver of accelerated cellular aging. C15:0, as a stable saturated fatty acid incorporated into membranes, reduces the substrate available for lipid peroxidation. The 2024 Cellular Stability Hypothesis paper formally proposes C15:0 deficiency as "Cellular Fragility Syndrome" — the first new nutritional deficiency syndrome in 75 years.

Pentadecanoylcarnitine (Endocannabinoid)

C15:0 produces a novel endocannabinoid metabolite, pentadecanoylcarnitine (C15:0-carnitine), with pleiotropic activity relevant to mood, inflammation, sleep, and physical health. This metabolite acts on CB1/CB2 receptors and has anti-inflammatory properties measured across multiple cell systems. Identified in a 2022 paper in Scientific Reports.

C15:0 vs. Rapamycin, Metformin & Acarbose

BioMAP Diversity PLUS system — 148 biomarkers across 12 primary human cell systems (Nutrients, PMC10649853, Oct 2023)

Using the gold-standard pharmaceutical phenotyping platform (BioMAP, used by pharma companies to screen drug candidates), researchers measured dose-dependent activities of C15:0 against three leading longevity-enhancing compounds. Results are the number of clinically relevant biomarker hits at each compound's optimal dose.

C15:0 (Fatty15)
36
hits at 17 µM · 10 of 12 cell systems
Rapamycin
32
hits at 9 µM · 12 of 12 cell systems
Metformin
28
hits at 5,000 µM (294× higher dose)
Acarbose
15
hits at 30 µM

Note: These are cell-based (in vitro) assays, not human clinical outcome data. They indicate mechanistic breadth and potency, not proven clinical equivalence. Rapamycin and metformin both have decades of clinical trial data that C15:0 does not yet match. Interpret accordingly.

100+ Publications — Research Categories

Breadth of peer-reviewed evidence across health domains

Heart Health Multiple studies
Metabolic Health RCT data · LDL, glucose
Liver Health TANGO RCT · ALT/AST data
Longevity Pathways AMPK · mTOR · sirtuins
Mood & Brain Health MAO-B inhibition · amyloid-β
Gut Health Bifidobacterium support
Anticancer Properties Multiple cancer types
Immune & Joint Health Anti-inflammatory
Lung Health Emerging data
Ocular Health Emerging data
Antimicrobial In vitro data
Pregnancy & Fertility Developmental studies
Essential Fatty Acid Formal classification push
Aging Rate Biomarkers Hemoglobin · RDW

Dosing Protocol

Based on clinical trial data and pharmacokinetic studies

Evidence-Based Dosing — C15:0 (Fatty15)

Maintenance / general longevity100 mg/day with a meal containing fat
C15:0 deficiency (elevated liver enzymes, low dairy intake)200 mg/day — Schwimmer RCT protocol dose
Target circulating level>5 µg/mL — clinical threshold where benefits were observed in RCT
Onset of measurable effect8–12 weeks to reach threshold; benefits dose and adherence-dependent
Testing availableAt-home C15:0 blood test available via discoverc15.com — confirms whether you are deficient
TimingWith fat-containing meal for optimal absorption
FormPure free fatty acid powder capsule (FA15) — not butter or dairy (concentration too low)

Safety Profile

Excellent safety record across all clinical trials — no significant adverse events reported in any study to date. No drug interactions identified. Side effects were statistically equivalent between fatty15 and placebo groups in the Schwimmer RCT. C15:0 is a naturally occurring dietary fatty acid present in whole-fat dairy — the supplement delivers a concentrated pure form. Long-term safety data beyond 12 weeks is limited; trials of 6+ months are needed.

Product — Only One Option

Fatty15 is the only commercially available pure C15:0 supplement; no generic competitors with equivalent purity currently exist

ONLY CLINICALLY STUDIED FORM
Fatty15
Fatty15 — Pure C15:0 (FA15)
Dose: 100 mg or 200 mg pure pentadecanoic acid per capsule
Form: FA15™ — pure free fatty acid powder, vegan, no fillers
Purity: 99%+ pure C15:0; third-party tested
Used in: All 6 clinical trials to date
Price: ~$1.40–$1.80/day depending on subscription tier

The only form of C15:0 tested in human RCTs. No generic equivalent with equivalent purity and clinical validation currently exists. Developed in collaboration with US Navy research. Subscription available — price per capsule drops significantly with 90-day subscription. Available via Amazon or direct.

Shop Fatty15 Direct ↗ Fatty15 on Amazon ↗
Generic C15:0 — Caution
Third-Party C15:0 Supplements
Purity: Variable — unverified in most cases
Form: Often mixed with other fatty acids
Clinical validation: None — no trials use generic C15:0
Price: Lower, but purity unconfirmed

As C15:0 awareness has grown, generic versions have appeared on Amazon and iHerb. EBL does not endorse these: purity is unverified, concentration is often lower, and none have been tested in clinical trials. If cost is a barrier, a 90-day Fatty15 subscription reduces per-dose cost significantly.