It may be common knowledge throughout the medical cannabis community that tetrahydrocannabinol, or THC, is not only a psychoactive cannabinoid, but that it is the most abundant cannabinoid found in Cannabis sativa. This is actually not quite true.

The most abundant cannabinoid found in living cannabis plants is actually tetrahydrocannabolic acid, or THCA, which is a precursor to THC. Unlike THC, THCA does not have psychoactive effects. Structurally, the only difference between the acid (THCA) form and its neutral form (THC) is a single molecule of carbon dioxide (CO2). The removal of that molecule of CO2, which results in the conversion of THCA to THC, is called decarboxylation. Decarboxylation occurs naturally in cannabis as it dries out, but it is also stimulated by exposure of cannabis to light or to heat. This is why it’s always a good idea to store dried cannabis in a cool, dark place. It is also why medical cannabis patients either vaporize or smoke their cannabis—to convert all THCA into THC.

THCA Medical Research

As with other cannabinoids, medical inquiry into the potential benefits of THCA is in its infancy, but is ongoing. Listed below are links to current, peer-review research into THCA.

Prostate cancer: Non-THC cannabinoids inhibit prostate carcinoma growth in vitro and in vivo: pro-apoptotic effects and underlying mechanisms
Inflammation: Evaluation of the Cyclooxygenase Inhibiting Effects of Six Major Cannabinoids Isolated from Cannabis sativa
Nausea and vomiting: Tetrahydrocannabinolic acid reduces nausea-induced conditioned gaping in rats and vomiting in Suncus murinus