When I first started writing about the claims made for medical marijuana and the cannabis oil derived from it, it didn’t take long for me to characterize medical claims for cannabis as the “new herbalism,” as opposed to pharmacognosy, the branch of pharmacology devoted to the study of natural products. The reason is simple. Although I support legalization of marijuana for recreational use, when I look at how medical marijuana has been promoted as a “foot-in-the-door” prelude to legalization, I see testimonials and flimsy evidence ruling over all. I see all the hallmarks of alternative medicine herbalism and none of the hallmarks of pharmacology. Here’s what I mean. Pharmacognosy examines an herb, plant, or other natural product and seeks to identify the chemicals within it that have pharmacological activity against a condition or a disease, the better to purify and isolate those chemicals and turn them into drugs. Herbalism, on the other hand, emphasizes the use of whole plants or extracts from plants, rather than the isolation of the most active compounds. Thus, herbal remedies often contain hundreds, or even thousands, of different compounds, of which only one or a few are active. Even extracts, such as cannabis oil, contain many compounds.
In contrast to pharmacognosy, herbalists make the claim that whole herbs and plant components possess a synergy that is missing from the purified active constituents and/or that the mixture is safer than the pure components because one compound can reduce the side effects of another without reducing therapeutic efficacy. When looked at closely neither claim stands up to scrutiny. Synergism between plant constituents is rare and very difficult to demonstrate, for example. In essence, herbalism turns back the clock 200 years to a time before scientists had developed the techniques and abilities to isolate active ingredients with pharmaceutical activity. Moreover, herbalism, in contrast to pharmacognosy, emphasizes anecdotes over scientific evidence.
Indeed, in my previous posts in this series on medical marijuana, one theme has emerged, which is that cannabis—specifically, a class of active chemicals in marijuana known as cannabinoids—has potential for some diseases but is not the panacea claimed by its proponents. It does not cure cancer, for instance, contrary to glowing testimonials promoted by people like Rick Simpson. For other conditions, the evidence is either not particularly compelling or only mildly promising.
So I reacted with considerable dismay on Friday night when I saw this news report on the 11 o’clock news, “Michigan panel recommends allowing marijuana for autism“: