Taking a specific amount of citrulline powder every day for a week makes certain amino acids go up in your blood, but it doesn’t change how your body builds or breaks down protein when you haven’t just eaten.

A study in 20-30 healthy adults where each participant receives citrulline (0.18 g/kg/day) and placebo for 7 days in random order with a washout period, with plasma amino acids measured at baseline and end of each phase, and whole-body protein synthesis, leucine appearance, and leucine oxidation measured via stable isotope tracer methods in the post-absorptive state.

A study comparing two groups of healthy adults: one receiving citrulline (0.18 g/kg/day) and the other placebo for 7 days, with plasma amino acids and protein metabolism markers measured at baseline and day 7 under post-absorptive conditions using stable isotope tracers.

A study where all healthy adults receive citrulline supplementation for 7 days, and changes in plasma amino acids and protein metabolism are measured before and after, using gold-standard tracer methods to confirm changes.

A study observing healthy adults who self-select citrulline supplementation for 7 days under tightly controlled diet and fasting conditions, measuring plasma amino acids and protein metabolism changes with tracer methods.

A small group of healthy adults taking citrulline for 7 days, with plasma amino acids and protein metabolism markers tracked before and after, using tracer methods to document changes.