In recent years, CBD has made hundreds of headlines as a life-changing natural remedy. The excitement over CBD is palpable; it feels like five more cannabidiol-infused products hit the market every single day and public opinion on the cannabis plant is evolving—in a very positive way—by the minute.
But this summer, Forbes published an article titled “Marijuana Study Finds CBD Can Cause Liver Damage” that made quite a few waves. The headline—and the research it was based on, which was published in the journal Molecules—threatened to muddy CBD’s so-far sterling reputation as a compound with an extraordinary safety profile. There was major pushback from CBD and cannabis experts who pointed out flaws in the study’s methodology and Forbes’ coverage of it.
Here’s what you need to know about the debate—about how CBD affects the liver.
CBD and the liver: The basics
The relationship between CBD and the liver is a close one; this is mostly because when you take CBD, it’s processed by the liver. According to Dr. Ethan Russo, a board-certified neurologist, psychopharmacology researcher, and former medical advisor to GW Pharmaceuticals, “cannabinoids are processed in various ways.” In fact, “some may even go out in the stool,” he says. But the majority of the breakdown occurs in the liver. Cannabinoids like CBD and THC are metabolized by a number of forms of the cytochrome P450 enzyme.
So how does the liver break down CBD? As Russo explains, “The primary breakdown of CBD occurs in the liver through hydroxylation.” According to him, hydroxylation means changing the CBD molecule slightly so that it can undergo additional changes to turn into an inactive metabolite, which can then be excreted from the body. In the case of cannabidiol, it’s hydroxylated to 7-hydroxy-cannabidiol. “After these initial steps, the liver continues to process the cannabinoids to inactive metabolites, which will be excreted in the urine,” says Russo.
According to DrugBank, a bioinformatics and cheminformatics resource that provides detailed drug date, CBD can be stored in the fatty tissue of the liver for as long as four weeks.
Can CBD damage the liver?
If CBD is processed by the liver, it would make sense that taking too much might hurt it, right?! According to an article on the non-profit online cannabis education platform Project CBD, it’s not that simple. The article—a direct rebuttal of the Forbes article and the study it cited—says that the doses used in the Molecules study were astronomically high, ranging from 246 mg/kg to 2460 mg/kg of CBD. For some perspective, most CBD oil products contain about 15 mg of CBD per serving—and that’s for humans. As Project CBD wrote: “The maximum human dosage recommended for the CBD-isolate Epidiolex is 20 mg/kg, which is over 100x less than what the researchers force-fed their experimental mice.”
The writers at Project CBD went further, calling the study, “A hit piece against CBD, not legitimate scientific work.” They also pointed out how the cannabis used in the study was provided by the National Institute on Drug Abuse and was extracted using hexane, which is a known neurotoxin and could have also played a role in the liver toxicity observed in the study.
It appears this reasoning was enough for Forbes to publish a follow-up article—in which they consulted a doctor and a scientist from Project CBD—that rolled back many of the claims made in the original article and acknowledged the flaws in the study.
But wait...can CBD benefit the liver?
Ironically, there is some science behind the idea that CBD could actually benefit the liver. According to Dr. Russo, “THC works on the CB2 receptor, which is antifibrotic. The same would be true for CBD.” In addition, cannabis usage seems to be helpful in people with hepatitis C, particularly in having them persist with their medicines to reach a cure.
On top of that, a University of Quebec study on 320,000 patients made headlines when it showed that drinkers who smoke cannabis have a significantly lower chance of developing liver diseases, including cirrhosis, steatosis, hepatitis, and even certain types of liver cancer.
When asked if this protective effect could be due to CBD’s antioxidant properties, Russo responded: “Absolutely; both CBD and THC and some of the terpenoids are antioxidants and they can change the body’s tissues.”
All that said, the processing of CBD by the cytochrome P450 enzyme does increase the risk of drug-medication interactions. More than 60 percent of pharmaceutical drugs are metabolized by the same enzyme and when you take CBD with those drugs, it can cause a deactivation of the enzyme.
So, what's the take-home? We're not sure all the ways that CBD can affect the liver. But from what we know so far, there’s no reason to think that CBD will damage your liver—at least not in reasonable doses.
Written By: Gretchen Lidicker, author of CBD Oil: Everyday Secrets, writer, researcher and go-to expert in all thing’s health and wellness.
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