evidence: Cannabinoids are a class of naturally occurring, biologically active molecules. Delta-9-tetrahydrocannabinol, more commonly known as THC, is a psychoactive cannabinoid found in marijuana – this is not produced in the human body. There are cannabinoids produced by the human body (endogenous cannabinoids) that act on the endocannabinoid system (ECS) to elicit neurological responses by binding to cannabinoid receptor type 1 and 2 (CR-1 & CR-2). The best studied endogenous cannabinoids include 2-arachidonoyl glycerol (2-AG) and arachidonoyl ethanolamide (anandamide). Endocannabinoids are thought to play a role in appetite stimulation, neonatal immunity, and brain development. So, it is not surprising that maternal endocannabinoids are incorporated into human milk.