The pharmacology does not support it
Overall, plasma citrulline is a functional (albeit unvalidated) marker of gut barrier dysfunction (Dey and Bhattacharjee, 2020), and lack of it has been associated with various intestinal diseases, including short bowel syndrome (Jeppesen et al., 2020
However, they are considered to be more effective than oral supplements as they facilitate the direct delivery of compounds into the bloodstream, and by extension, into the skin and other target organs by skipping the digestive process
Figures are compiled for laboratory documentation from published research and community reconstitution practice they are not medical advice, not human-use directions, and not a claim of safety or efficacy
Nasal spray wins only on convenience
J Nutr 2001