Cannabidiol (CBD) and tetrahydrocannabinol (THC) are chemical compounds called cannabinoids that act on the endocannabinoid system (ECS) in the brain, organs, glands, connective tissues and immune cells. Described as the bridge between the mind and body, the ECS helps maintain/restore a healthy biological balance (or homeostasis) that adjusts for external changes in environment. As needed, the human body naturally produces endocannabinoids like anandamide (AEA), 2-arachidonoylglycerol (2-AG) and 2-arachidonyl glyceryl ether from arachidonic acid derivatives in the cell membrane. The cannabis plant, from which the system gets its name, contains at least 100 cannabinoids including THC, CBD, cannabinol (CBN), cannabigerol (CBG) and others that act on the same ECS receptors.
Whether released by the body or the plant, cannabinoids promote healthy ECS function and adaptation to harmful stressors. To date, researchers have identified numerous medicinal benefits from cannabis-based cannabinoids, but the compound that seems to have the most promise is CBD. When extracted into liquid form, CBD oil allows for concentrated, measured dosage, and since the cannabinoid is non-psychoactive, CBD use is safe for children, recovering addicts and patients operating vehicles/machinery. Nevertheless, CBD poses an interesting question for the research community, i.e., whether the cannabinoid loses some of its medicinal efficacy when isolated away from THC and other cannabis compounds.
How does CBD work? The exact mechanism of action is not entirely clear, but cannabinoids in general act on two main receptor types: CB1 primarily in the central and peripheral nervous system and CB2 primarily in the immune system. THC can bind directly to both types of receptors, but CBD lacks binding affinity for the primary receptors. Rather, CBD appears to simulate the natural production of the endocannabinoid AEA, limit its reabsorption and block the enzyme that metabolizes it. Likewise, CBD binds to other receptors, notably the serotonin-binding 5-HT1A (mood), TRPV1 (pain, inflammation, body temperature) and adenosine A2A (cardiovascular, respiratory). While it does not directly act on the ECS, the cannabinoid might improve the receptors’ density and coupling efficiency, and it appears to deactivate the cancer-proliferating GPR55 receptor. In the medical community, CBD shows promise as a primary or complementary treatment for numerous diseases and disorders, including anxiety, epilepsy, inflammation, diabetes, rheumatoid arthritis, multiple sclerosis, opiate addiction, neurodegenerative disorders, heart disease, Parkinson’s, Alzheimer’s, Crohn’s disease, Dravet’s Syndrome and even certain types of cancer.
Whole-Plant Cannabis Medicine
Various extraction methods (e.g., ethanol, solvent, grain alcohol, super-/sub-critical C02) help isolate CBD in an oil form, but some studies suggest that whole-plant cannabis might have greater medicinal benefits. For example, a study published in Molecular Cancer Therapeutics in 2014 investigated the effects of THC and CBD and found that whole-plant cannabis can prime glioma cancer cells to respond better to ionizing radiation. Dr. Sean McAllister, a government-backed researcher at the Pacific Medical Center, contributed to a 2010 study in the same journal that said “THC and cannabidiol (CBD) acted synergistically to inhibit cell proliferation,” while his other research found that CBD impairs metastatic cancers of the brain and breast by inhibiting ID-1 gene expression. Higher amounts of CBD appear to reduce the psychoactive effects of THC, but interestingly, it also inhibits the breakdown of THC in the liver extending its therapeutic benefits. Additional studies show that THC helps CBD maximize its antioxidant potency.
The two cannabinoids seem to have a symbiotic relationship that fosters mutual enhancement, but that does not necessarily mean that whole-plant therapy is ideal for every disorder. In some cases, a single-cannabinoid therapy might be more efficacious, and the specific cannabinoid might be THC, CBD, CBN or an entirely different cannabis compound altogether. Likewise, the benefits of whole-plant therapies might be negligible or substantial depending on the particular disorder and the patient. These questions highlight the need for comprehensive clinical studies that provide more precise information about the medicinal use of cannabis compounds. The findings from such studies will better inform health professionals on the use of cannabinoid-based medicine.