C15:0 / Pentadecanoic acid (Fatty15)

LongevityEmergingMetabolic

An odd-chain saturated fatty acid that may be the first essential fatty acid identified in 90 years. Emerging evidence; not yet established.

EvidenceEmerging

Early human trials and biomarker work positive: improved liver function, red cell membrane integrity, inflammatory markers, modest lipid effects. The 'essential fatty acid' framing is contested — not yet established by mainstream nutritional science. Effects: 12+ weeks for biomarkers.

C15:0 (pentadecanoic acid) is a saturated fatty acid found in whole-fat dairy. Researcher Stephanie Venn-Watson and team proposed in 2020 that low C15:0 levels may underlie a 'Cellular Fragility Syndrome' that accelerates aging, and that supplementation reverses biomarker changes associated with metabolic decline. The branded form (Fatty15) is C15:0 in pure form. Early human trials are showing improvements in liver fat, red blood cell membrane integrity, and inflammatory markers. The claim that C15:0 is 'the first essential fatty acid discovered since omega-3 in the 1930s' is bold and not universally accepted. Treat as promising-but-emerging.

Form: Fatty15 (branded pure C15:0). Generic versions becoming available. Or consume whole-fat dairy.
Dose: 100 mg/day (the Fatty15 dose). Up to 300 mg/day in some emerging research.
Timing: With a meal. Once daily.
Schedule: Daily.
Side effects: Generally well-tolerated. Mild GI upset rare.
Interactions: No established interactions. Limited data.
Contraindications: Pregnancy / lactation — limited safety data. Active liver disease (caution).
Lab markers: C15:0 in red blood cell membrane (specialty labs offer this — useful baseline + follow-up). Liver enzymes if tracking liver outcomes.
Food sources: Whole-fat dairy (butter, full-fat milk, full-fat yogurt, cheese) is the primary food source. Some grass-fed beef. The shift away from full-fat dairy in modern diets may be why C15:0 levels have dropped at population scale.

Pairs with

Omega-3 fish oil (complementary fatty acid). Generally no established synergies.

Where to buy

Curated pick

C15:0 / Pentadecanoic acid is exclusively sold under the Fatty15 brand (the company holds the patent + research program). ~$45/month subscription, direct-to-consumer at fatty15.com. No generic equivalent on Amazon. Promising emerging evidence for cellular longevity (the 'first essential fatty acid discovered in 90 years' claim).

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