We have covered the basics of the major THC variants, CBD and their interactions with the endocannabinoid system. Next is one of the minor cannabinoids found in cannabis, usually in very low amounts, if it is present at all. Although "minor" in quantity, cannabigerol shows the promise of major medical benefits.

Phytocannabinoid: Cannabigerol (CBG)

Cannabigerol is the phytocannabinoid from which all others are derived. Phytocannabinoid synthesis starts with the terpene geranyl which is combined with olivetolic acid to form CBGA. The CBGA is then converted to THCA, CBDA or CBCA by specific enzymes (or synthases) produced by the plant. It is the activity of these synthases, dictated by the plant's genetics, which primarily determine the relative ratios of phytocannabinoids produced by a particular cultivar (strain). Hemp cannabis strains, cultivated to produce more CBD and low levels of THC will typically have more CBG content than high THC cultivars. Selective breeding to produce a larger percentage of THC has resulted in strains with increased activity of the THCA-synthase enzyme, which converts a larger proportion of CBGA to THCA , leaving less CBGA in the cannabis. CBD dominant strains are bred to have lower THCA-synthase activity leaving more CBGA behind in the cannabis. Certain cultivars produce much higher or only CBGA by having genetically low or absent enzyme activity to convert CBGA to the other phytocannabinoids.

Like all phytocannabinoids, the acidic version of CBG (CBGA) is produced by cannabis. Decarboxylation of CBGA converts it into the active CBG form which interacts with the endocannabinoid system. The effects of CBG on the endocannabinoid system are, of course, not completely understood. It has shown weak activity at the CB1 receptor and may partially block some of the effects of THC. Although not fully determined at this point in time, CBG appears to have activity at the CB2 receptor by partial activation and/or increasing the receptor's response to the endocannabinoid 2-AG. This is important to know in determining how CBG fits into your treatment with medical cannabis. CB2 receptors, to review, are present throughout the body but are most prevalent outside of the central nervous system on cells of the gut and immune system. It is the indirect action of CBD on the CB2 receptor (by increasing 2-AG activity) that CBD exerts its anti-inflammatory effects. Having another phytocannabinoid which influences CB2 and therefore inflammation, allows an opportunity to further reduce inflammation which is a feature of many disease states. Controlling inflammation is a cornerstone of controlling symptoms and possibly the progression of the many disorders with it as a prominent feature.

Cannabigerol is not psychoactive like THC and produces no euphoria. The medical benefits of CBG include the reduction of inflammation in the treatment of Crohn’s disease, ulcerative colitis, neurodegenerative conditions (e.g. Huntington’s disease, multiple sclerosis, Parkinson’s disease, etc.) and possibly psoriasis and arthritis. The ability to regulate inflammation suggests a possible role in treating autoimmune conditions. It has been found to decrease intraocular pressure (treats glaucoma), inhibit cancer cell growth, have pain relieving effects and stimulates the appetite. CBG has effects on the inhibitory GABA pathway in the brain, increasing the amount of GABA present. This results in muscle relaxation and anti-anxiety properties.

Although cannabigerol is present in low concentrations, its presence in some chemovars is still significant. Full spectrum CBD tinctures usually contain some relatively small amount of CBG, other minor cannabinoids and terpenes. It is interesting to note that patients respond better and at lower doses to full spectrum CBD products than the single molecule "industrial hemp" CBD preparations. The entourage effect certainly comes into play and CBG may have a significant role of its own as well as when combined with other phytocannabinoids

There are several cultivars which have very high levels of or exclusively produce CBG. They are relatively rare and difficult to find as much of the industry eyes the recreational cannabis market, concentrating on the production of high THC strains. Cultivating a strain which produces only a single, somewhat obscure non-euphoric cannabinoid is a risky venture for growers. Those cultivators and dispensaries with a strong dedication to patients and the future of medical cannabis are beginning to taking note. I expect to see the development of strains which express chemovars aimed at specific symptoms and disease processes. CBG will be an important consideration. The benefits of CBG observed in the scientific literature and the very positive results I have directly seen patients in my practice achieve with the addition of higher doses of CBG incorporated into their medical cannabis treatment, suggest a major role for this minor cannabinoid.

Back to the Big Picture and Chemovar Considerations

CBG is currently a small, percentage wise, piece of the cannabinoid puzzle. Even in the low concentrations present in some chemovars, it has significant medical benefits for many conditions. Patients with inflammation as a component of their conditions, such as inflammatory bowel diseases, neurodegenerative conditions, arthritis, peripheral neuropathy, fibromyalgia, cancer and autoimmune diseases should consider chemovars with a showing of CBG preferred. CBG exclusive cultivars should be combined with chemovars appropriate for your particular condition.

Optimal dose of CBG is unknown and has to be individualized. As a starting point, I am currently suggesting 10mg/day CBG (as tincture) in addition to the appropriate chemovar for the condition. For patients who prefer the inhalation route of administration, a 2 parts of the selected chemovar flower to 1 part White Whale CBG flower (14% CBG, 0% THC, 0% CBD) is the suggested starting dose. If mixing CBD flower with medical cannabis to achieve a more balanced profile, a 1:1:1 ratio of cannabis, CBD flower and White Whale is recommended. Dose needs to be individualized to the response observed. The combination of cannabinoids will be more effective than any individually- remember the entourage effect.

Brian Nichol MD
Cannabis Expert