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]
