L-leucine is an essential branched chain amino acid that supports muscle protein synthesis and energy production. It can also be used as a nutrient.
L-Leucine
Found In
- Energy drinks
- Dietary supplements
- Protein powder beverages
- Sports drinks
- Naturally occurring in eggs, fish, meat, milk and poultry
Also Known As
- E641
- 2-Amino-4-Methylpentanoic Acid
The Beverage Bottom Line
L-leucine is authorized for use in the U.S., Europe and Canada.
This ingredient may have authorizations in countries not included on this site.
International Assessments and Authorizations
U.S. Food And Drug Administration (FDA)
Generally recognized as safe for intended uses. (GRAS FDA-Notified, GRAS Self-Determined)
European Food Safety Authority (EFSA)
Safe for intended uses. Permitted for addition in dietetic foods.
Joint FAO/WHO Expert Committee on Food Additives (JECFA)
Safe for intended uses.
In 2007, WHO published a Technical Report on Protein and Amino Acid Requirements in Human Nutrition.
Health Canada
Safe for intended uses. Permitted as a supplemental ingredient.
In 2005 and 2006, dietary reference intakes for L-leucine were reviewed by the National Academies of Sciences, Engineering and Medicine.
This page was last updated on 6/30/2025.