Evidence Trace, complete trial record

In plain terms

In plain terms: Pentadecanoic Acid (C15:0) shows early signals in human research but the evidence is limited -- small trials, surrogate endpoints, or not yet independently replicated. It is an emerging area, not yet a proven one.

Pentadecanoic Acid (C15:0)

C Limited: small, mixed or unreplicated trials

Category Supplements

Evidence Two small randomized controlled trials

Reviewed September 2026

PMIDs 38035997 · 39069269

The endpoint this grade is based on: Surrogate biomarker endpoint, LDL cholesterol lowering in one trial, on top of a weight-loss diet in women with fatty liver disease; not yet replicated, and no clinical endpoint has been tested

The evidence as the record states it

Evidence record

PMID 38035997 PMID 39069269

Chooi et al. (Am J Clin Nutr, 2024; PMID 38035997), the TANGO trial: 88 Chinese women with fatty liver disease were randomized for 12 weeks to an Asian-adapted Mediterranean diet with C15:0, the same diet without it, or their usual diet. C15:0 was given as 300 mg a day in soymilk supplied by a commercial food manufacturer. Both diet arms lost weight and liver fat; adding C15:0 lowered LDL cholesterol further and shifted the gut microbiome. Robinson et al. (J Nutr, 2024; PMID 39069269): 30 young adults with overweight or obesity randomized 2:1 to 200 mg C15:0 a day or placebo for 12 weeks. The primary outcome was the blood level of C15:0, which rose. Lower liver enzymes and higher hemoglobin were seen only in the half of the treated group whose level passed 5 micrograms per mL, a comparison of responders rather than of randomized arms. Grade C: two small trials, one surrogate benefit that has not been repeated, and no clinical endpoint.

PMID 38035997 PMID 39069269

Why Grade C and not Grade B

Grade C reflects early or limited human evidence -- small trials, surrogate endpoints, or preliminary findings not yet independently replicated. The evidence points in a promising direction but does not yet meet the standard for Grade B. A single well-powered, independently replicated trial with a meaningful endpoint would move this to Grade B or higher.

What this grade covers and what it does not

Close to the line between C and D, and C is the honest letter. Two randomized trials have given C15:0 to people. In one (TANGO) it lowered LDL cholesterol beyond what a weight-loss diet achieved, a surrogate result from a single trial that nobody has repeated. In the other its pre-specified outcome was only whether the blood level rises, and the encouraging liver-enzyme numbers come from splitting the treated group by response, which randomization does not protect. Most of the published C15:0 literature is cell work, animal work and observational association with dairy fat intake, none of which enters a grade. A replicated trial on a clinical or functional endpoint at a stated dose would move this record. WHAT THIS GRADE DOES NOT COVER: aging, longevity or cellular health, which are how C15:0 is sold and which no trial has measured. It does not cover the 100 mg retail serving, which is below both studied doses, and the LDL result does not transfer to someone who is not also on a weight-loss diet, because that is the only setting in which it was seen.

What would move this grade

A well-powered randomized trial with an objective, clinically meaningful primary endpoint and at least one independent replication would support Grade B or higher.

How this was studied

Form: Pure C15:0: capsules in one trial, fortified soymilk in the other · Dose: 200 mg/day and 300 mg/day · Population: 88 Chinese women with fatty liver disease on a weight-loss diet; 30 young adults with overweight or obesity · Duration: 12 weeks in both · What is sold differs: Sold as a healthy-aging capsule at 100 mg, one or two a day. The trials used 200 to 300 mg, tested liver and cholesterol markers rather than aging, and the LDL result was on top of a weight-loss diet.

How to track whether this is working LDL cholesterol, ALT and AST at baseline and 12 weeks, the endpoints the two trials measured. Plasma C15:0 if available: in the 200 mg trial, only participants whose level passed 5 micrograms per mL showed the liver-enzyme change.