What makes CBD evidence poor?

    Written by:
    Pierre-Alexandre Sicart
    Last Updated: May 16, 2025

    The evidence for CBD is considered poor due to the limited number of human trials, which are often short in duration, and a reliance on animal studies that may not accurately reflect human responses. Additionally, there are concerns that CBD could potentially worsen certain types of cancer, which highlights the need for more comprehensive research.

    A 2019 review noted that human trials were few,[1] and they still are few in 2022. Most studies are in animals, and animal studies often translate poorly to humans[2] (CBD appears to be more bioavailable for rodents than for humans, notably[3]).

    Moreover, what human trials we have didn’t last very long,[4] so we don’t know much about the long-term effects of CBD. For example, like cannabis itself, CBD has been touted as a potential cancer treatment,[5] yet CBD-induced receptor activation could theoretically worsen certain types of cancer, such as colon cancer.[6]