Norvaline is a non-protein amino acid. It acts as an inhibitor of arginase, the enzyme that breaks down arginine. This slows arginine loss, helping the body produce more nitric oxide.
Higher nitric oxide relaxes blood vessels. Athletes take norvaline hoping this boosts blood flow, nutrient delivery, and muscle pumps during training.
Doses in studies often range from 100 to 500 mg. Safety data in humans is thin. Pregnant or nursing women, and anyone with blood pressure concerns or on vasoactive medications, should skip it until more is known.