L-Norvaline
A non-proteinogenic amino acid added to pre-workouts to inhibit arginase and raise nitric oxide. There are no human trials at all, and its long-term safety is unknown.
Evidence last reviewed: August 2026
What the science says
- No human evidence Limited evidence
No randomised trial has tested norvaline supplementation in humans for blood flow, pumps or exercise performance. The rationale is entirely mechanistic, based on arginase inhibition in vitro.
- Animal data are metabolic, not ergogenic Limited evidence
A rodent study reported antihyperglycemic effects of L-norvaline with L-arginine in high-fat-diet, streptozotocin-treated rats. This says nothing about exercise outcomes in healthy people.
Dosage & safety
Studied doseNo studied dose. Pre-workout labels typically list 100–500 mg, a figure chosen without trial support.
SafetyUnstudied in humans. Norvaline can substitute for leucine during protein synthesis, and no long-term human safety data exist. Best avoided in pregnancy and by anyone with liver or kidney disease.
Scientific references
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Related in Physical performance
- Creatine (monohydrate) Strong evidence
- Whey Protein Strong evidence
- Caffeine Strong evidence
- Beta-Alanine Moderate evidence
- BCAA (Branched-Chain Amino Acids) Limited evidence
- EAA (Essential Amino Acids) Moderate evidence