L-norvaline

Amino-acid

What is it

L-norvaline is a non-proteinogenic amino acid (an isomer of valine) marketed in pre-workout and 'nitric oxide booster' supplements based on its ability to inhibit arginase.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Nitric oxide / pump support

Mixed Evidence

Mechanistic data on arginase inhibition exist, but human evidence that L-norvaline at supplement doses produces meaningful nitric oxide or performance benefits is lacking.

How it works

L-norvaline inhibits arginase, the enzyme that breaks down arginine. The supplement rationale is that less arginase activity should leave more arginine available for nitric oxide (NO) synthesis, supporting blood flow and pump. Cell and animal studies support arginase inhibition, but human evidence that supplement-level norvaline meaningfully increases nitric oxide or performance is limited.

Dosage

Pre-workout products typically include 100-300 mg of L-norvaline per serving. No RDA exists.

When and how to take it

Used as part of pre-workout stacks, typically 20-30 minutes before exercise.

1 commercial form

Compare the main delivery options and what they’re best suited for.

L-norvaline

Used in pre-workout blends.

Oral absorption likely; specific pharmacokinetics not well characterized.

Safety

Limited safety data in humans. Theoretical concerns about long-term neurotoxicity have been raised based on animal studies of non-proteinogenic amino acids incorporating into proteins, though clinical significance in humans is unclear.

Who should be cautious

Pregnancy and breastfeeding: avoid (no safety data). People with neurological conditions should be cautious given theoretical neurotoxicity concerns. Discuss with a clinician if you take cardiovascular medications.

Interactions

Theoretical interactions with antihypertensives or other nitric-oxide-affecting drugs. Limited clinical interaction data.

Food sources

Trace amounts in some bacterial fermentation products

Amount
negligible
%DV
—

Frequently asked questions

Does L-norvaline boost nitric oxide?⌄

Mechanistically plausible by inhibiting arginase, but human evidence for meaningful NO or performance benefits at supplement doses is weak.

Is L-norvaline safe long-term?⌄

Long-term safety in humans is not well-established. Theoretical concerns from animal data exist; using cautiously and not chronically is reasonable.

References

L-norvaline on Wikidata — Wikidata link

L-norvaline on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on L-norvaline (PubMed search) — PubMed link

Track L-norvaline with Pilora

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.