Does CBD Convert to THC After Ingestion? New Research Says No

Cannabidiol (CBD) has been shown to be an effective anti-convulsant therapy for several different types of epilepsy and epilepsy-like conditions, such as Dravet syndrome. These diseases primarily affect children, and there are very few effective medications on the market.

A growing number of parents are turning to CBD to treat their epileptic children, but in many places, it is viewed as taboo, primarily because of the well-known psychoactive effects of smoking the cannabis plant. A common criticism is that these parents are doing more harm by getting their kids “high”. There is little truth to this argument, as THC is the main psychoactive ingredient in cannabis, and not CBD. However, it is possible that this criticism has some merit, as studies have shown that CBD can be chemically converted into THC by simulated gastric juices.  Whether or not this occurs in the context of the gastrointestinal tract is still controversial. Previous clinical studies of CBD therapies have not reported elevated blood plasma levels of THC or its metabolites, but these are incidental findings, and not the main subject of the research itself.

A new paper recently published in the journal of Cannabis and Cannabinoid Research takes aim at this question specifically, and has shown that CBD does not convert to THC after ingestion.

The Study

As with most scientific work, an animal model was used for the experiments performed in this study. Specifically, the authors chose to work with minipigs. Their reasoning for this is that the digestive tract in pigs is very similar to that of humans, more so than other commonly used laboratory animals. Further, pigs have an omnivorous diet, like humans, and both the acidity level and the transit time are very similar. Another important reason for using pigs is that they share two genes with humans that are required to metabolize THC. Because of this, the researchers were able to use a simple blood draw to test for THC metabolites; if the pigs did not have these enzymes, the test would not have worked.

The setup for these experiments was fairly simple. The pigs were given an oral dose CBD solution twice a day for four days, with a final morning dose on the fifth day. On the first and last day, blood samples were drawn over the course of several hours to track the overall rates of CBD absorption and metabolism. This step was very important, because it allowed the researchers to compare their minipig data with human clinical data and ensure that their model would accurately represent what happens in humans. Finally, the pigs were euthanized several hours after the final dose, and their stomach contents examined for traces of THC. This was done to provide a more direct measurement of possible CBD-to-THC conversion in the gastrointestinal tract.

The results were quite straightforward. The blood testing was able to detect CBD at the expected levels after dosing, demonstrating that the drug was being absorbed and metabolized properly. At each timepoint, no THC or THC metabolites were present in the blood, suggesting that there was no CBD-to-THC conversion taking place. The same was true for the stomach content samples; CBD was detected, THC was not. Therefore, this work has shown that, in a reasonable animal model at least, CBD does not convert to THC in the intestinal tract.


As always, it is important to keep in mind the shortcomings of this research. This work was performed using only three animals, which is a very low sample size; more replicates may be needed to ensure credible results. Obviously, pigs are not humans, and so more clinical data needs to be collected to really determine whether or not this CBD-to-THC conversion takes place. A final consideration is that the authors of this study are all employees of GW Pharmaceuticals, a publicly-traded company that has developed two cannabis-based treatments that are awaiting FDA approval. It would be in the company’s best interest if this research proved to be accurate.

Nevertheless, this work is important for a few reasons. First of all, it should put to rest some fears parents may have about treating their children with oral dose CBD. As a fairly new and highly controversial treatment option, it’s understandable that many parents may have reservations about its use. Therefore, work of this type is important to help doctors guide their patients and make them feel comfortable with a new treatment option. Furthermore, this research can also provide a point of refutation for those who make accusations based on ignorance. Finally, there are some people who have strong, adverse reactions to THC, and therefore may be wary of trying out CBD-based medications for fear of accidentally dosing themselves with THC. This research, along with a growing body of clinical data, demonstrates that those fears may not be based in scientific fact.


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