Earlier in the year, we published an article about CBD converting to small amounts of THC in the stomach, based on a 2016 study lead by John Merrick, “Identification of Psychoactive Degradants of Cannabidiol in Simulated Gastric and Physiological Fluid”. This study found that cannabidiol, when immersed in a bath of acid similar to stomach acid, produces a significant amount of THC in the same acid bath. Researchers hypothesized that this was because THC and CBD, despite having wildly different effects, actually start as the same pre-cursor chemical (cannabigerolic acid). Different enzymes then convert this chemical to destination chemicals THC or CBD, depending on plant genetics and environmental factors.
However, strangely enough, in the year following the study, we have not seen the results confirmed. Were this a less significant finding, we might expect such delay. However, the finding is especially relevant to cannabis/cannabinoid research because it undermines CBD as a therapeutic drug. If part of the drug is converting to THC in stomach acid, this effect might preclude its use in situations where THC must be avoided. However, despite the lack of confirmation, outstanding questions loom, such as, if edible CBD converts to THC, why are CBD users not noticing psychedelic effects? How did such a large, obvious conclusion fly below the radar?
Apparently because it’s false.
As far as we can determine at this point in time, there is no reason to believe CBD converts to THC in the human stomach. Spearheading the commentary refuting this article, Franjo Grotenhermen and Ethan Russo have written a new article, “Even High Doses of Oral Cannabidiol Do Not Cause THC-Like Effects in Humans: Comment on Merrick et al. Cannabis and Cannabinoid Research 2016:1(1):102-112.”. As readers may remember from previous articles, Russo is an acclaimed neurologist and psychopharmacology researcher, known for being a pioneer of cannabinoid study in general.
Starting the rebuttal, authors note studies establishing the wealth of evidence confirming that edible CBD does not cause any of the typical psychological effects, impairment of psychomotor and cognitive performance, etc. or even physical effects, including increased heart rate and dry mouth, that THC causes. Authors go on to quote study after study confirming opposite effects. The main point behind quoting this evidence is to make a point; “if CBD is converting to THC, it clearly is not converting at a level to be noticeable in any performance testing”. However, according to Merrick’s original study, the THC levels are indeed chemically significant. Authors of the rebuttal proposed three possibilities to explain this discrepancy:
1) Perhaps stomach acid does not degrade CBD as effectively as test acid
2) Since CBD produces nearly opposite effects of THC, it counteracts the effect of any THC it produces itself
3) The original authors used methanol to dissolve CBD, which does not occur in human stomachs (methanol causes blindness)
In any of these cases, the authors state, the most important ultimate conclusion is human testing. Whether or not something works in the lab, the most important question is if it is a viable medicine in real life.
Concerned parents and users of CBD may still worry about micro-effects of CBD to THC conversion. Readers may wonder why authors of the rebuttal feel so confident staking their careers on their position. Most obviously, if THC is being produced, serum levels of THC in the blood will show spikes. However, this has never been documented. As authors state, “to the contrary…the plasma sample of 14 patients with Huntington disease, who received CBD during 6 weeks” at a high dose, “showed that no THC was detected in the plasma sample of any patients at any time during the trial”. Authors go on to quote a second study confirming that the reverse has also been observed; THC does not convert to CBD.
We tend to leave a lot of articles open-ended as we are often in the position of needing to wait for more research, especially human trials. However, given the lack of evidence here…combined with the observation that CBD tends to produce opposite results…combined once again with one of the leading researchers of the field speaking out against the only study to say otherwise, we are very confident: CBD does not convert to THC in the human body, and CBD edibles are perfectly safe for non-psychedelic applications.
Grotenhermen F, Russo E, Zuardi AW (2017) Even High Doses of Oral Cannabidol Do Not Cause THC-Like Effects in Humans: Comment on Merrick et al. Cannabis and Cannabinoid Research 2016;1(1):102–112; DOI: 10.1089/can.2015.0004, Cannabis and Cannabinoid Research 2:1, 1–4, DOI: 10.1089/can.2016.0036.