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Limited evidencePhysical performance

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.

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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.

How to take it

TimingNothing about timing has been tested in humans, so no schedule is better than another.
With food?With or without food; absorption has not been studied.
Worth knowingNorvaline can be mistakenly built into proteins in place of leucine, and there is no human safety data, so the sensible move is to leave it out of your stack.

Frequently asked questions

Does L-norvaline boost nitric oxide or pumps?

No human trial has tested L-norvaline for blood flow, pumps or exercise performance; the rationale rests only on arginase inhibition in the lab. The evidence for L-norvaline is limited to mechanism.

Is L-norvaline safe?

L-norvaline is unstudied in humans and has no long-term safety data, and it can substitute for leucine during protein synthesis. The sensible move is to leave L-norvaline out of your pre-workout, and avoid it in pregnancy or with liver or kidney disease.

How much L-norvaline is in pre-workouts?

Pre-workout labels typically list 100–500 mg of L-norvaline, a figure chosen without trial support. There is no studied dose of L-norvaline.

Scientific references

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