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Every time something is proclaimed as a natural cure-all ,or miracle supplement, or superfood, a divisive and contentious battle tends to follow. 

Turmeric either sustains your health in a dozen different ways, or doesn’t contain enough curcumin to have a measurable effect. Bone broth is either an ancient cure-all for joints and skin, or an overhyped scam with little nutritional value.

The battle over CBD, it seems, has just begun. The first shot across the bow (and across the pages of Forbes and Motley Fool) came on Monday with this headline:Marijuana Study Finds CBD Can Cause Liver Damage.” 

The Study

The study was divided into two stages and used full-spectrum hemp-derived CBD. 

In the first acute phase, the mice were given extremely high doses of CBD and observed for 24 hours. The mice saw increases in a number of metrics indicating liver damage: liver-to-bodyweight ratio, plasma ALT,  enzyme markers, and total bilirubin. 

In the second sub-acute phase, over the course of 10 days mice were gavaged “allometrically scaled mouse equivalent doses (MED) of the maximum recommended human maintenance dose of CBD in EPIDIOLEX® (20 mg/kg)” (Ewing et al. 2019). Translation: they were given the mouse equivalent (proportionally speaking) of the highest recommended human dosage of CBD in the CBD-based epilepsy drug Epidolex (used to treat severe epilepsy in children). 

These mice quickly started showing signs of liver damage. Some died. Worse, it turns out that Epidolex, the only CBD-based drug approved by the FDA, warns specifically on the label that their drug carries a risk of liver damage. In their clinical trials, 5-20% of participants developed elevated liver enzymes (elevated liver enzymes=liver damage). 

2 Reasons to Not Get Carried Away with the CBD / Liver Damage Storyline

Sounds scary, right? But that’s not all there is to it. 

Problem 1: Dosage

So the scientists took the highest recommended dosage of CBD in Epidolex and found the proportional equivalent (in terms of bodyweight) for a mouse. What is the highest doctor recommended dosage of CBD via Epidolex? 1400mg.

Keep in mind this is for treating children with severe seizures. Most CBD oils range from 250-500mg of CBD per bottle. The typical recommended dose is 20-40mg. The doses in the sub-acute phase, then, were the mouse equivalent of 1400mg of CBD each day. This would be the equivalent of a person drinking several bottles of CBD each day!

And the doses in the acute phase that caused liver damage were even higher, as much as 10x higher! So now we’re talking about the equivalent of drinking dozens of CBD bottles each day.

The fact that CBD causes liver damage at all is certainly cause for concern (more on that in a minute). But the fact that the damage was caused by proportionally massive doses of CBD lessens the concern a bit. 

Problem 2: Lack of Corroboration by Other Studies

Findings from any scientific study should always prompt the following question: Do Other Studies Corroborate this Study?

The answer in this case: not really. Epidolex’s case studies found that around 10% of participants saw an increase in liver enzymes , with 2-3% of participants having to discontinue the treatment entirely due to risky levels of liver enzymes. We see a few problems with this:

  1. This is with the Epidolex recommended doses, which are MUCH higher than regular doses. It’s unclear how relevant these findings are to regular doses.
  2. Epidolex is a pharmaceutical that contains more than just CBD, so we can’t isolate the specific effect of CBD alone.
  3. The participants were children suffering from epilepsy, not healthy adults. 

What do other studies on CBD and the liver show? Here are some highlights from the studies we found:

  • We propose that CBD, by selectively inducing death of activated HSCs, represents a potential therapeutic agent for the treatment of liver fibrosis.” (Mukhopadhyay et al. 2011)
  • “CBD significantly reduced the extent of liver inflammation, oxidative/nitrative stress, and cell death.” (Mukhopadhyay et al. 2011)
  • “In comparison with other drugs, used for the treatment of these medical conditions, CBD has a better side effect profile.” (Iffland & Grottenhermen 2017)
  • “Cannabidiol restores liver function, normalizes 5-HT levels and improves brain pathology in accordance with normalization of brain function.” (Avraham 2011)

Of the studies we reviewed that touched on CBD and liver function, nearly all of them described CBD as having liver protective qualities. 

While it’s true that the endocannabinoid system is “an important player in the pathophysiology of liver disease,” (Caraceni et al. 2008) CBD also regulates “50 more genes, many of which were linked to oxidative stress responses, lipid metabolism pathway and drug metabolism enzymes” (Ewing et al. 2019).

In short: CBD is “linked to” or “regulates” a whole host of hormonal and physiological processes, and we understand very little of all these effects.

The Takeaway

CBD science is still in its infancy, and we have virtually zero data on long-term use. Studies like this shouldn’t be discounted, but they should be put in context. 

Nearly all the CBD studies we’re aware of have found CBD to be low-risk with relatively few side-effects. Studies specifically pertaining to CBD and the liver do NOT yet corroborate the claim that CBD causes liver damage, and indeed some claim the opposite. 

At the same time, drugs like painkillers and alcohol are known to damage the liver, so it’s not unthinkable that CBD could incur similar damage. If you’re currently using or are considering using CBD, this study alone shouldn’t deter you. But keep in mind that there is potential risk there, and keep an eye out for future studies.

Sources Cited