LEUCINE

📋 Quick facts

Description: LEUCINE — amino acid, part of the skin natural moisturizing factor (NMF).

All Functions: amino acid, part of the skin natural moisturizing factor (NMF)

Quick Facts:

• Category: humectant

Proven Benefits At A Glance:

• Leucine appears in research primarily as part of protein structures and signaling molecules, not as a standalone skincare ingredient
• Sources discuss leucine-rich proteins involved in cancer biology, immune function, and wound healing—not topical leucine benefits
• No sources provide evidence that leucine applied to skin improves appearance, texture, or skin health

⚗️ Chemical Overview

Leucine is a branched-chain amino acid that consists of glycine in which one of the hydrogens attached to the alpha-carbon is substituted by an isobutyl group. It has a role as a Daphnia magna metabolite. It is a branched-chain amino acid and an alpha-amino acid. It contains an isobutyl group. It is a conjugate base of a leucinium. It is a conjugate acid of a leucinate. DL-leucine has been reported in Homo sapiens, Pisum sativum, and other organisms with data available. See also: L-Leucine (annotation moved to).

Source(s): LOTUS – the natural products occurrence database, PubChem, ChEBI, via PubChem

📊 Comedogenicity

🛡️ Safety rating

Safety tier is a starting heuristic from regulatory status and comedogenic rating, not a dermatological verdict — see our Terms for the full disclaimer. Research confidence reflects how many real cited studies back this ingredient, not the strength of their findings.

🌍 Regulatory Status

💧 Skin Type Compatibility

⚠️ Don’t Combine With

📚 Research & Evidence

🔬 The Science

The research abstracts provided do not contain evidence supporting leucine as a consumer skincare ingredient. Instead, they discuss leucine in highly specialized biomedical contexts unrelated to topical skincare. Here’s what the sources actually address: The sources mention leucine-rich structures in specific proteins like LGR5 (a cancer stem cell marker studied in organoid screens for antibody development, per Cancers Basel 2025) and LRRK2 (a Parkinson’s disease biomarker, per Cureus 2025). One source discusses small leucine-rich proteoglycans (SLRPs) as extracellular matrix components with roles in wound healing—including anti-inflammatory and pro-angiogenic properties in skin repair (Front Pharmacol 2019). However, this research concerns how these proteins function internally during wound healing processes, not how topical leucine application would affect skin.

Another source examines lysine/leucine-rich antimicrobial peptides in laboratory studies of tumor-associated macrophages (Int J Mol Sci 2025), which relates to cancer immunotherapy research, not skincare. The psoriasis research mentions GC-Induced-Leucine-Zipper (GILZ), a protein involved in anti-inflammatory signaling pathways, but discusses systemic glucocorticoid therapy and potential future therapeutics—not topical skincare products (Front Immunol 2019). In summary: these sources do not evaluate leucine as a skincare ingredient, do not contain consumer-relevant skin benefits, and do not provide a foundation for skincare marketing claims about leucine.

📄 Related Research

Matched by search — not necessarily verified support for every statement above.

• Lundberg AS et al. (2025). Petosemtamab, a Bispecific Antibody Targeting Epidermal Growth Factor Receptor (EGFR) and Leucine-Rich G Repeat-Containing Protein-Coupled Receptor (LGR5) Designed for Broad Clinical Applications. Cancers (Basel).
• Sevilla LM et al. (2019). Glucocorticoids and Glucocorticoid-Induced-Leucine-Zipper (GILZ) in Psoriasis. Front Immunol.
• Pang X et al. (2019). Small Leucine-Rich Proteoglycans in Skin Wound Healing. Front Pharmacol.
• Heineman A et al. (2025). Challenges and Opportunities of Early Parkinson’s Disease Biomarkers: α-Synuclein, Leucine-Rich Repeat Kinase 2 (LRRK2), DJ-1, and microRNAs. Cureus.
• Li Z et al. (2025). Lysine-Leucine-Rich Frog Skin Antimicrobial Peptides Inhibit Breast Cancer Metastasis by Reprogramming Tumor-Associated Macrophage Polarization. Int J Mol Sci.

🧴 Products Containing LEUCINE

• Seba Med Seifenfreies Waschstück
• sebamed Flüssig-Wasch-Emulsion
• BCL Kansosan Skincare Moisture Base AQ
• RETINOL RETINOL SKIN CREAM
• MyProtein Hair & body wash
• Bioélixire Odżywka do włosów zniszczonych
• today, today med Waschlotion (für empfindliche Haut)
• Tío Nacho Tío Nacho Anti-Caida Engrosador
• marc anthony argan shampoo
• Pacifica Cosmic Hemp Balancing Face Wash
• NIOD Multi-Molecular Hyaluronic Complex (MMHC2)
• The Ordinary The Ordinary Glycolic Acid 7% Toning Solution (Solução tonificante de ácido glicólico 7%)
• ordinary suncream
• dr groot shampoo
• Paul Mitchell Paul Mitchell Awapuhi Shampoo
• collagen face mask
• OPLAPLEX Leave In – Numéro 5
• Sephora Beauty insider
• Olaplex No. 8 Bond Intense Moisture Mask
• FILORGA TIME-FILLER Crème Absolue Correction Rides
• Klorane Bébé Crème lavante nourrissante cold cream
• Klorane Klorane Bébé Baume corps au cold cream
• Klorane Klorane Bébé Crème hydratante Physio Calenduline
• Klorane Klorane Bébé Crème Nutritive Cold Cream
• Klorane Gel douceur moussant
• Bébé Klorane, Klorane, Klorane bébé, Laboratoires Klorane, PHYSIOcalenduline, Pierre Fabre Eau nettoyante micellaire sans rinçage
• CeraVe Hydrating cream-to-foam cleanser
• Filorga Filorga Hydra Filler 50ML
• CeraVe Hyrdrating Cream To Foam Cleanser
• Davines Davines MOMO Moisturizing Shampoo
• SebaMed Seifenfreies Waschstück
• sebamed sebamed Frische Dusche
• Moroccan oil body lotion
• Atomy Atomy absolute BB no.23 spf 50
• Essano expertise 02 Volumising Conditioner
• Asianic Hair Conditioner
• averac caviar
• The Ordinary Natural Moisturizing Factors + HA
• sirius groom shampoo
• Dm Leichtkämm spray