Is L-Leucine safe in cosmetics?
L-Leucine has a safety rating of "EXCELLENT" in our database. EU status: permitted. US status: permitted.
Excellent
Antioxidant
L-Leucine
Also known as: Leucine, L-, L-2-Amino-4-methylpentanoic acid, Leu, L-(-)-2-Amino-4-methylpentanoic acid, 2-Amino-4-methylpentanoic acid, (S)- (+15 more)
INCI: LEUCINE
L-Leucine (CAS 61-90-5) is a cosmetic antioxidant functioning as Essential branched-chain amino acid that inhibits lipid peroxidation and. EU Regulation 1223/2009 status: permitted. Industrial safety data is also available in the chemical safety database. Same-CAS public records also appear in industrial chemical safety and pharmaceutical data.
View industrial chemical safety profile for CAS 61-90-5 →
Auto-generated CPSR Part A draft with source citations
Function
Essential branched-chain amino acid that inhibits lipid peroxidation and enhances accessibility of fat-soluble ROS. The hydrophobic isobutyl side chain partitions into lipid membranes and sebaceous environments, scavenging fat-soluble reactive oxygen species and disrupting lipid peroxidation chain reactions. Also commonly used as a slip agent and texture modifier in cosmetic powder formulations.
Safety Rating
EXCELLENT
Chemistry & Identifiers
IUPAC Name
(2S)-2-amino-4-methylpentanoic acid
InChIKey
ROHFNLRQFUQHCH-YFKPBYRVSA-N
Regulatory Status
EU EU Status
permitted
US US Status
permitted
US Notes
FDA GRAS as direct food additive. CIR amino acid class assessed safe.
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for L-Leucine.
Calculate MoS for your specific formulation with the MoS Calculator.
ECHA REACH Registration
European Chemicals Agency REACH dossier and Substances of Very High Concern listing.
Registration Type
Full
Tonnage Band
100 - 1,000 tonnes
Substance Type
SUBSTANCE
SVHC Candidate
No
Additional Ingredient Properties
3 property records from structured ingredient metadata.
acne
{"cas_number": "61-90-5", "anti_acne_mechanism": "anti_inflammatory", "comedogenicity_rating_0_to_5": "0", "acne_type_efficacy": "inflammatory", "sebum_reduction_pct_clinical": "0-5", "prescription_required_usa": "No", "otc_drug_monograph_category": "No", "max_otc_concentration_pct": "No limit", "japan_quasi_drug_anti_acne": "No", "korea_functional_cosmetic_acne": "No", "eu_cosmetic_restriction_ac…
anti_aging
{"anti_aging_claim": "barrier-repair", "mechanism_of_action": "Building block for proteins, NMF component", "target_skin_layer": "epidermis", "collagen_stimulation": "Mild", "elastin_protection": "Mild", "wrinkle_reduction_pct": "4-8", "clinical_study_duration_weeks": "8", "sample_size": "25", "double_blind": "No", "placebo_controlled": "Yes", "published_journal": "Int J Cosmet Sci", "improvement_…
pediatric_safety
{"safe_for_newborn_0_6m": "yes", "safe_for_infant_6_12m": "yes", "safe_for_toddler_1_3y": "yes", "safe_for_child_3_12y": "yes", "safe_for_teen_12_18y": "yes", "pediatric_max_concentration_pct": "5.0", "adult_max_concentration_pct": "5.0", "pediatric_dermal_absorption_factor": "normal", "diaper_area_safe": "yes", "pediatric_allergy_prevalence": "low", "banned_in_children_products_eu": "no", "banned…
PubChem Annotations
Safety and regulatory annotations from PubChem (NCBI) aggregated sources.
Safety (1)
Carcinogen Classification
No indication of carcinogenicity to humans (not listed by IARC).
Source: Toxin and Toxin Target Database (T3DB)
Regulatory (2)
JECFA Number
1423
Source: Joint FAO/WHO Expert Committee on Food Additives (JECFA)
JECFA Evaluation
L-LEUCINE | 2004 | No safety concern at current levels of intake when used as a flavouring agent | Not evaluated using the Procedure for the Safety Evaluation of Flavouring Agents; the substance is a macronutrient and a normal component of protein and, as such, human exposure through food is orders of magnitude higher than the anticipated level of exposure from use as a flavouring agent | TRS 928-
Source: Joint FAO/WHO Expert Committee on Food Additives (JECFA)
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Anti-static agent
Flavouring and nutrient
Softener and conditioner
Regulatory List Membership (2)
EU Restricted for Children (Cosmetics)
FDA Substances Added to Food (EAFUS)
Expert Verdict
Expert safety assessment and concern-level summary for L-Leucine.
Regulatory Flags
gras-fda
cir-approved
antioxidant
lipid-peroxidation-inhibitor
branched-chain
slip-agent
eu_children_restricted
fda_food_additive
jecfa_safe
Known Synonyms
Leucine, L-
L-2-Amino-4-methylpentanoic acid
Leu
L-(-)-2-Amino-4-methylpentanoic acid
2-Amino-4-methylpentanoic acid, (S)-
EINECS 200-522-0
FEMA No. 3297
Valeric acid, 2-amino-4-methyl-, (S)-
Leucina
Leucinum
UNII-GMW67QNF9C
(2S)-2-Amino-4-methylpentanoate
(2S)-2-amino-4-methyl-pentanoic acid
(S)-2-Amino-4-methylpentanoate
(S)-2-Amino-4-methylvalerate
4-Methyl-L-Norvaline
L-Leuzin
L-a-Aminoisocaproate
L-a-Aminoisocaproic acid
L-alpha-Aminoisocaproate
Chemical Function
Anti-static agent
Softener and conditioner
Flavouring and nutrient
Regulatory Lists
Europe
food_additive; Substances Added to Food (formerly EAFUS) (2/2019)
pharmaceutical
children; Europe; Personal care
children; Europe; Personal care
Cross-Vertical Safety Context
Same-CAS public records found in pharmaceutical data.
SOURCE
ChEMBL / DrugCentral / FAERS
DB_PHARMA CAS match
Pharmaceutical Data
Same-CAS rows from the pharmaceutical spoke database.
Compound
LEUCINE
ChEMBL ID
CHEMBL291962
Max Phase
3
Adverse Event Associations
8
Frequently Asked Questions
Is L-Leucine allowed in the EU?
L-Leucine EU regulatory status: permitted. This is based on EU Regulation 1223/2009 and its amendments.
What does L-Leucine do in cosmetics?
L-Leucine functions as: Essential branched-chain amino acid that inhibits lipid peroxidation and enhances accessibility of fat-soluble ROS. The hydrophobic isobutyl side chain partitions into lipid membranes and sebaceous environments, scavenging fat-soluble reactive oxygen species and disrupting lipid peroxidation chain reactions. Also commonly used as a slip agent and texture modifier in cosmetic powder formulations.. It is classified as a Antioxidant in our database. CAS number: 61-90-5.
Is L-Leucine used outside cosmetics?
L-Leucine also appears in industrial chemical safety and pharmaceutical data. The cross-vertical cards on this page render same-CAS public rows from the matched databases.
Compliance Tools
Check L-Leucine compliance across multiple jurisdictions:
Ingredient Decoder
Paste a full ingredient list for instant analysis
82 Allergen Checker
Check for EU declarable fragrance allergens
Substance Compliance
Check compliance across multiple jurisdictions
MoS Calculator
Calculate Margin of Safety using SCCS methodology
Heavy Metal Limits
Compare limits across jurisdictions
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