Study: Some CBD Oils Equally, Less Effective Than Pure CBD At Inhibiting Cancer Cell Lines


Study indicates pure CBD was able to reduce cell viability in 3 of the 6 cell lines and that this effect was cell line specific rather than specific to certain cancers.

New research suggests that cannabidiol (CBD) oils are equally or less effective than pure CBD at inhibiting the growth of certain cancer cell lines, indicating that future research into the clinical uses of cannabinoids should analyze whether pure CBD or the intact plant material is more effective.

According to a press release, earlier research has found that CBD or tetrahydrocannabinol (THC) can reduce cancer cell viability in some cancer cell models. Proponents of medical marijuana argue that there is an additive effect between the various compounds in the plant material, increasing its therapeutic efficacy compared with individual, pure cannabinoid compounds. This concept, known as the entourage effect, is not supported by the study’s findings, according to the authors.

Investigators studied brain, skin, and colorectal cancers, with 2 cell lines for each cancer type. They found that pure CBD was able to reduce cell viability in 3 of the 6 cell lines and that this effect was cell line-specific rather than specific to certain cancers. None of the CBD oils tested were able to reduce viability to a greater extent than the pure CBD.

“Based on our results, we recommend that specific investigations on the entourage effect be carried out when determining the therapeutic uses of medical marijuana and other cannabinoid products,” said researcher Kent Vrana, PhD, in the press release.

The investigators said they carefully designed the study so that the amounts of CBD oil used for testing had an equivalent amount of CBD as the pure CBD used in the experiments. They used 3 types of CBD oil with certificates of analysis and had their composition verified by a third-party laboratory. Equal concentrations were used to treat each of the 6 cell lines.

After evaluating the viability of the treated cell lines, the team determined that the CBD had an effect on 1 of each of the colorectal cancer, melanoma, and glioblastoma cell lines. The viability of the other lines tested was no significantly reduced.

Vrana noted that because a previous study evaluating the use of THC in breast cancer cells suggested an entourage effect in that context, careful testing of cannabinoids should be done for each proposed therapeutic context.

“Pure CBD had the ability to reduce certain cancer cell types’ viability in this study,” Vrana said in the statement. “It would be reckless for a consumer to assume that a CBD oil product off the shelf could have the same effects for them, which is why careful studies around the entourage effect are needed for each intended therapeutic application.”


Certain CBD oils no better than pure CBD at inhibiting certain cancer cell lines [news release]. Penn State News; November 17, 2020. Accessed December 1, 2020.

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