E641 · L-Leucine
- FDA
- Safe
- EFSA
- Safe
- FSANZ
- Safe
- Japan
- Safe
- UK FSA
- Safe
- Health Canada
- Safe
What is E641?
L-Leucine is an essential branched-chain amino acid, meaning the body cannot make it and it must come from food. As a food additive it is mainly used as a flavour enhancer to round out savoury notes, and it is also popular in sports and nutrition supplements for its role in muscle protein synthesis.
Also appears on labels as: L-Leucine, Leucine, L Leucine, 2-Amino-4-methylpentanoic acid, Leu, Essential amino acid leucine, L-Leucine powder, L-Leucine supplement, Leucinum, Leucine (L form), E641, E 641.
What the evidence says
- Generally recognized as safe at the levels used as a flavour enhancer or in typical supplement doses.
- Very high supplemental doses of leucine or other single amino acids, taken chronically, may cause amino acid imbalances or strain metabolism in susceptible individuals.
Frequently asked questions
Is E641 safe?
Our overall verdict for E641 (L-Leucine) is “Safe”, based on the most cautious of the major regulators’ positions — FDA: safe; EFSA: safe; FSANZ: safe; Japan: safe; UK FSA: safe; Health Canada: safe.
Is E641 vegan, halal or gluten-free?
According to our ingredient data for L-Leucine — vegan: yes, vegetarian: yes, halal: yes, kosher: yes, gluten-free: yes, dairy-free: yes. Manufacturing sources can vary between products; check the label if it matters to you.
What is E641 and why is it used?
L-Leucine is an essential branched-chain amino acid, meaning the body cannot make it and it must come from food. As a food additive it is mainly used as a flavour enhancer to round out savoury notes, and it is also popular in sports and nutrition supplements for its role in muscle protein synthesis.
Does E641 contain allergens?
No known allergens are recorded for L-Leucine.
Watch E641
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This page summarises publicly available regulatory assessments and research. It is general information, not medical advice. Sources: EFSA, FDA, WHO and the studies linked above.