Ingredient intelligence
Linoleic acid
Skin barrier · Linoleic Acid · C18H32O2
Linoleic acid is an essential polyunsaturated fatty acid required for acylceramide formation in the epidermal barrier.
Molecular identity
- Formula
- C18H32O2
- Molecular weight
- 280.4 g/mol
- PubChem CID
- 5280450
- ChEBI
- CHEBI:17351
Biological targets
PNPLA1 acyltransferase
medium confidencetargets · enzyme
Transfers linoleate onto omega-hydroxyceramides.
UniProt Q8N8W4Peroxisome proliferator-activated receptor alpha (PPARA)
low confidenceactivates · receptor
UniProt Q07869
How could this ingredient interact with biology?
Biological network
Ingredient → molecule → target → gene/protein → pathway → process → studied outcome. Relationship strength is drawn from the curated confidence tier; nothing is added to make the chain look complete.
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2 lower-confidence relationships are hidden at this filter level. Use “Show more biology” to include them.
Text alternative for this network
- Linoleic acid is molecule Linoleic acid — high confidence
- Linoleic acid targets PNPLA1 acyltransferase — medium confidence
- PNPLA1 acyltransferase encoded by PNPLA1 — medium confidence
- PNPLA1 participates in Sphingolipid metabolism — medium confidence
- PNPLA1 participates in Fatty acid metabolism — medium confidence
- Sphingolipid metabolism associated with Epidermal barrier formation — medium confidence
- Fatty acid metabolism associated with Epidermal barrier formation — high confidence
- Epidermal barrier formation studied in Deficiency is associated with barrier dysfunction — high confidence
Biological pathways
Sphingolipid metabolism
medium confidenceAcylceramide synthesis requires linoleate.
Reactome R-HSA-428157
Fatty acid metabolism
high confidenceEssential fatty acid handling.
Reactome R-HSA-8978868
Evidence engine
Insufficient
Not enough curated evidence to characterise this ingredient.
Skinceptor Evidence Index
24
experimental · of 100
This index is a research-navigation aid describing how much evidence exists and how it was produced. It is not a medical safety score, an efficacy guarantee, or a clinical recommendation.
Study composition
- Animal1
- Review2
- Total studies
- 3
- Human studies
- 0
- Largest sample
- Data unavailable
- Range
- 1996–2016
Index breakdown
- Study design quality42% × 28%
Mean design weight across curated studies (meta-analysis 1.0, RCT 0.9, other human 0.7, review 0.45, animal 0.35, in-vitro 0.25).
- Human evidence share0% × 22%
Proportion of curated evidence measured in people rather than cells or animals.
- Evidence volume63% × 14%
Log-scaled count of curated studies, so volume alone cannot dominate the score.
- Largest sample size0% × 12%
Log-scaled largest reported sample size across curated human studies.
- Replication0% × 12%
Independent human studies, capped at three; one study is never treated as replicated.
- Recency50% × 7%
Linear decay over a twenty-year window from the most recent curated publication.
- Source traceability0% × 5%
Share of curated studies with a verified PMID or DOI in this dataset.
Insufficient comparable evidence for quantitative synthesis.
Research timeline
How the evidence accumulated
1996
Physiological lipid mixtures and accelerated barrier recovery
Animalsample size unavailable · Archives of Dermatological Research
2003
Stratum corneum lipids and barrier function: ceramide, cholesterol and free fatty acid ratios
Reviewsample size unavailable · Journal of Lipid Research (review)
2016
Essential fatty acid deficiency and epidermal acylceramide formation
Reviewsample size unavailable · Journal of Lipid Research (review)
Ingredient fingerprint
10 nodes · 12 relationships · seed "linoleic-acid"
The fingerprint is a deterministic visual signature: ridge amplitude comes from the number of entities in each tier, node placement from identifier hashes, and opacity from confidence. Two ingredients can never produce the same figure unless their networks are identical.
Open in Biology as Art →Research
3 curated studies
Essential fatty acid deficiency and epidermal acylceramide formation
Establishes linoleate as required for omega-O-acylceramide formation, with PNPLA1 mediating the transfer step.
Limitations — Review of genetic and animal evidence; topical repletion effects less characterised.
Stratum corneum lipids and barrier function: ceramide, cholesterol and free fatty acid ratios
Establishes the approximately equimolar ceramide/cholesterol/free fatty acid composition required for competent lamellar barrier structure.
Limitations — Review; ratio requirements derived largely from animal and ex-vivo models.
Physiological lipid mixtures and accelerated barrier recovery
Reported that only balanced ceramide/cholesterol/fatty acid mixtures accelerated barrier recovery; incomplete mixtures delayed it.
Limitations — Animal model; identifier not verified during curation.
Community evidence
Submitted by readers
Reader submissions appear here only after review. They are not part of the curated dataset and do not affect the Skinceptor Evidence Index.
No approved community submissions yet.
Sources
- PubChem 5280450retrieved 2026-09-14
- UniProt Q8N8W4retrieved 2026-09-14
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