No, CBD Is NOT Toxic To Your Liver

Or your anything. Here’s why.

Forbes recently published this scary headline: “Marijuana Study Finds CBD Can Cause Liver Damage.” They were reporting on a University of Arkansas for Medical Sciences study claiming that mice given high doses of CBD showed signs of liver damage within 24 hours—and 75 percent of them were dead or nearly so within days.

If you’re one of the millions of people who has been relying on CBD for your health for years, this is no doubt confusing and terrifying.

CBD may cause liver damage–we’re not doctors and this is not medical advice. But we did connect with mathematician/chemist Adrian Devitt-Lee,  a recipient of the Norbert Wiener Award in Mathematics from Tufts University, and chief science writer for Project CBD about why the study (and especially Forbes’s write-up) can be misleading to a layperson.

Sketchy conclusions

The study concludes that high doses of CBD killed the mice, or brought them to the brink of death. However, there were several problems with these conclusions.

“The main issue was that the doses were so extremely high,” says Devitt-Lee. “They have an argument to justify this dose, but they don’t present any evidence validating their argument.”

The maximum recommended dose for ingesting pure CBD is 20 mg/kg in humans, though up to 50 mg/kg has been used in epilepsy treatment. In the study, the researchers used up to 2,460 mg/kg— orders of magnitude higher.

“Additionally, some of the numbers the authors report are just wrong,” Devitt-Lee says. “The most startling one is the number of mice that died: 75 percent of 6 mice. But multiplying this out, you realize it means that 4.5 mice died. I don’t know how they ended up with that number. When their most serious outcome is misstated, what can I trust in the study to be true?”

Furthermore, the authors of the study itself incorrectly cited the literature in the field—whether accidentally or intentionally.

“There were at least two points where the authors mis-referenced their citations,” says Devitt-Lee. “In one case, they claimed that CBD is toxic to the cardiovascular system based on a UK study which found that CBD could lower blood pressure.”

Actually, the abstract of the report says, Further research is required to establish whether CBD has a role in the treatment of cardiovascular disorders.

“It is clear the UK scientists are not suggesting CBD is harmful in this reference, and it only takes a few minutes to verify this,” Devitt-Lee points out. “Did the authors not read the report they were citing? Or did they intentionally misrepresent it? I hesitate to assume ill intention, but it’s a problem in either case.”

Shoddy methods

The conclusions reached were not the only trouble with this study, which was “riddled with issues,” according to Devitt-Lee.

For example, the researchers claimed to use GC/MS to detect heavy metals and bacterial contamination, but this doesn’t make sense. Furthermore, other methods were actually dangerous for their subjects.

After making any extract, some residual solvent will be left over. They decided to use a highly toxic chemical for extraction (hexane), which is not used in commercial cannabis products,” Devitt-Lee says. “Their formulation wouldn’t be legal to sell in many states in the US because of the large amount of residual hexane.”

Furthermore, the work was error-ridden enough that the researchers were caught in errors by others. “According to someone who contacted me after our response, the authors admitted that the decarboxylation temperature was misreported,” says Devitt-Lee. “They had written it was done at 80 C, but it was actually at 130 C.”

“I am not experienced in some of the other techniques they used, so I couldn’t report on the validity of the whole methods section. But through and through, the methods and the reporting were sloppy.”

Even sloppier reporting

The reporting by Forbes on this research is the worst kind of media, making bad science even more dangerous. For Devitt-Lee, this all comes down to scientific literacy.

“It is easy to confuse ‘I don’t know’ with ‘It’s unknown,’” Devitt-Lee says. “In the Forbes piece, the journalist uses his own tenuous understanding of cannabis to insist that no one else can fathom its medical complexity.”

This is clearly what writer Mike Adams believes: it is his position that there can be no such thing as a “marijuana expert.”

“No one is claiming to know the ideal way to take advantage of cannabis, but we can give a lot more detail to contextualize a claim that CBD causes liver damage and death,” Devitt-Lee says, refocusing the issue. “If he doesn’t understand science well enough to critique it (which is quite apparent), he needs to talk with experts before reporting—not claim that no expert could possibly exist. Part of this comes down to scientific literacy, and recognizing that a single study (or a single person’s experience) rarely proves much.”

Another issue here is that evidence on CBD is being presented selectively—a practice that is antithetical to good journalism.

Devitt-Lee says,People get caught up with a narrative, but science is about data. There are so many studies that have shown the safety of CBD, yet these are ignored so as to write a compelling story.”

The rest of the story, as Devitt-Lee points out, is that Epidiolex, a purified form of CBD, does have a warning about elevated liver enzymes:

“Nearly every report has involved valproate, another anti-epileptic drug. Monitoring liver function is especially important for people taking isolate CBD with valproate, but that’s not a concern for most consumers. One can address potential dangers without exaggerating, but overstating the results casts a shadow on everything.”

This same journalist wrote a second piece insisting that CBD is not even effective for epilepsy (or any other disease), since only one third of patients with epilepsy experience major benefits.

“While this number is more or less true (it may be closer to 40 percent who find significant benefit), that’s still huge,” says Devitt-Lee. “The probability that any other drug works in intractable epilepsy is around 6 percent, so CBD helping in 30 to 40 percent of cases is way better than what other antiepileptic drugs offer such patients. But since he’s trying to craft a narrative contrary to CBD’s popularity, he ignores that important details. The truth is overtaken by the story he wants to tell.”

Devitt-Lee sees this as evidence of the need to do more work shifting the cultural narrative toward seeing cannabis as medicine.

“Considering public health doesn’t just mean harms. A number of epidemiological studies have come out in the past 5 to 10 years showing that cannabis use is associated with lower weight, better insulin sensitivity, a lower likelihood to die from pancreatitis, better outcomes in nonalcoholic fatty liver disease, and so on. There’s even been a significant amount of research suggesting that cannabis use is associated with a healthier gut in patients with schizophrenia, which is still a taboo subject. Sure, pay attention to psychosis and driving and other possible harms, but recognize that there are many health benefits of cannabis use, even among recreational users.”

“It comes down to experimentation. Cannabis is a very safe drug and many people already use it well enough to benefit. Facilitate patients’ experimentation in as safe a setting as possible, then listen to them. Learn from them.”

Main takeaway: more research needed, but don’t give up on CBD due to the Forbes fearbait article.

*Adrian Devitt-Lee is the winner of the Norbert Wiener Award in Mathematics from Tufts University, an MS in mathematics, and a BA in chemistry. He has authored extensive works in peer-reviewed publications concerning cannabis, gene mutations, and cannabinoid-pharmaceutical interactions. His chemistry research at the University College in London is ongoing.

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