Vanillin gives vanilla its characteristic taste and smell. As a supplement it serves as a flavoring agent. People do not take it for direct health outcomes.
Any calming or mood shift tied to vanilla comes from smelling it, not from swallowing vanillin. No solid clinical data show that oral vanillin changes mood, sharpens thinking, or relaxes the body.
Safety information for oral use at supplement amounts is sparse. Large doses can upset the stomach. Animal work hints that very high doses may slow blood clotting, so vanillin could interact with blood thinning drugs. Because no standard dose range exists, any use beyond flavoring calls for extra care.