CBD (cannabidiol) is a cannabinoid found in marijuana, but it doesn’t have any psychoactive effects (in other words, it doesn’t cause a high). The cannabinoid in marijuana that causes a high is THC (tetrahydrocannabinol), not CBD.
Recently, there’s been a huge surge of interest in the health benefits of CBD and a predictable increase in the number of products with CBD added to them: on top of the basic CBD oil, there’s a whole range of eatable and drinkable CBD products from fizzy soft drinks to lattes to brownies. CBD is more acceptable than THC-containing products to people who can’t or don’t want to get high, and there's some interesting evidence that it may help with pain, anxiety/depression, and possibly insomnia.
If you believe all the marketing hype, CBD is the new elixir of life, but as usual, the marketing is way overhyped. Here’s a look at the actual research, but first...
Is this stuff even legal?
As this post explains, it’s complicated. In the US, CBD isn't considered a dietary supplement and it isn't regulated like normal supplements. The legal status of CBD depends on whether your particular state has legalized recreational and/or medical marijuana use, and possibly on whether the CBD in question is extracted from marijuana or industrial hemp. 17 states also have laws specific to CBD. Here's a map showing which states have what kinds of laws, with details available for each state.
The federal government still considers marijuana-derived CBD to be illegal (although some CBD sellers have argued that this doesn't technically apply to hemp-derived CBD), but in practice, enforcement is patchy at best and CBD is pretty widely available, especially online. Here is a research paper breaking it down in extreme detail, for the curious. In short, it's very hard to say and trying to figure out the relevant laws is a recipe for a headache: here's to hoping that we get some clarity on this soon.
Is it safe?
This review looked at precisely that question and concluded that it probably is. The researchers found that CBD is mostly safe and definitely safer than a lot of common psychiatric medications. When people had side effects, the most common reported problems were fatigue, diarrhea, and changes in weight and appetite - none of those are fun, but none of them are really deadly. But the authors also noted that:
“some important toxicological parameters are yet to be studied, for example, if CBD has an effect on hormones. Additionally, more clinical trials with a greater number of participants and longer chronic CBD administration are still lacking.”
A bigger problem for a lot of interested consumers is that the CBD market is barely regulated, so it can be really hard to find products that actually contain the advertised amounts of CBD. A 2018 study found that many commercially available CBD products didn’t contain the amount of CBD advertised on the label. One study found that only 30% of CBD products were accurately labeled to reflect the amount of CBD they actually contained (26% contained less CBD than they claimed; 43% contained more than they claimed). Even more concerningly, the study found that nearly 20% of products sold as pure CBD actually contain at least some THC (that’s the chemical in marijuana that does get you high).
This is all important for anyone thinking of trying CBD to consider: when you buy a supplement, you ought to feel confident you're getting the label ingredients and nothing else, but that's just not the case with a lot of CBD products.
Does it work? Evidence in humans
Based on evidence that it's helpful, the FDA has approved an oral formulation of CBD as a treatment for drug-resistant epilepsy in children. CBD is also approved in Canada to treat pain from multiple sclerosis. But most people who walk into a CBD store aren’t children with epilepsy or MS patients: what about the rest of us?
A couple of studies have examined CBD oil for pain in humans, particularly chronic pain. For example, This review of reviews concluded that some reviews found evidence of benefits for multiple sclerosis (MS) pain and spasticity.
Other studies (here and here) have found benefits of CBD for cancer pain specifically. And in this study of 303 patients with allodynia (that’s a problem where you weirdly feel pain from things that shouldn’t hurt), a combined THC/CBD spray was safe and effective, even in patients who didn’t respond to other painkillers.
This study found that CBD definitely doesn’t mess with normal sleep patterns and suggested that it might be helpful for restoring altered sleep patterns.
Brain health/mental health
On top of being FDA-approved for treating epilepsy, this review of human studies explains how CBD may have some antipsychotic properties, but the conclusion highlights the need for way more big, high-quality studies before anyone starts claiming anything about it for sure.
This review of CBD for mental health and psychiatric issues also stresses the call for more research - the authors found a little bit of evidence for treating symptoms of social anxiety and schizophrenia, but noted that “most of the studies published presented several drawbacks and did not reach statistical significance.”
This review, specifically on anxiety, also noted that the human studies so far are all on acute administration (you give someone CBD once and see how they feel), not chronic administration (you give someone CBD every day for three weeks and see how they feel), which is another huge gap in the research.
This aspect of CBD just doesn't enough research to draw clear conclusions in humans, although it would be really great to find out that there's actually a benefit.
Two more miscellaneous items to round off the list:
- This review found five human studies suggesting that CBD may be helpful for people trying to quit smoking cigarettes.
- This study is also fascinating: unlike THC, CBD (16 mg, delivered via inhaler) actually improved subjects' ability to recognize facial expressions and match them to emotions.
What do actual CBD users say?
Finally, there’s this survey. The researchers in this study didn’t actually give CBD to anyone. Instead, they asked current CBD users why they use it. Of course, this is only surveying people who liked CBD enough to stick with it, so it’s biased towards people who had a good experience with CBD.
About two-thirds of those people said they used CBD for medical reasons, with the most common reasons being chronic pain, arthritis/joint pain, anxiety, depression, and insomnia. Just over a third of respondents claimed that CBD worked “very well” to address their problem. About one third also reported some kind of minor side effect. The most common side effects were dry mouth (11% of people), euphoria (6.43%), hunger (6.35%), and red eyes (2.74%).
Again, this isn’t a super rigorous test of efficacy, but it’s interesting in the absence of big clinical trials on some of these things.
Does it work? Evidence in animals
Predictably, there’s more of it and it looks pretty neat.
For example, animal studies have found that CBD relieves pain and inflammation in a variety of contexts. Here’s a study on eye pain in mice; here’s one on arthritis pain and inflammation in rats that improved after rubbing CBD oil directly on the affected areas. This study also found that CBD reduced the inflammation and immune dysfunction involved in fatty liver disease in rats
Animal research on the mental health/brain health benefits of CBD also looks promising. For example, this study found that oral CBD helped alleviate depressive symptoms in rats genetically prone to depression and this one found some interesting fast-acting antidepressive benefits. A review of cannabis and cannabinoids in sleep disorders found that CBD alleviated insomnia in animal models, but studies in humans are still really limited.
This type of animal research is where a lot of claims about the benefits of CBD come from, but animal research doesn’t necessarily translate into human benefits.
CBD and Paleo or Keto
None of these studies examined the combination of CBD oil and diet, although the potential anti-inflammatory effects definitely seem to complement a Paleo-style approach to health.
One major worry, especially for the low-carbers, might be “will CBD give me the munchies?” - but fortunately, this study found that low doses of CBD didn’t cause sweet cravings or increase liking of sweet foods.
From a Paleo perspective, CBD oil also comes under scrutiny for fat quality - and that goes double for any kind of CBD candy, CBD cookies, CBD drinks, and other edibles. But other than that, the studies above suggest that it’s compatible with a Paleo diet and lifestyle habits - like any other supplement, the question is really whether it's right for you and whether you have a clear reason to be taking it. The Paleo approach isn't about out-supplementing a bad diet, but there's definitely a role for a few carefully-chosen supplements to complement a base diet of nutrient-dense whole foods.
So what does it all mean?
Ultimately, these studies suggest that the biggest risk of taking CBD might not be the CBD itself but rather the chance of getting a contaminated supplement or one that’s inaccurately labeled (causing you to take more or less than you think you’re taking). There’s also the question of legal status, which is incredibly unclear and confusing in most places.
It’s also true that the evidence doesn’t support the really extreme claims about CBD, like the idea that it prevents/cures cancer or that it’s some magical therapy for chronic pain in all patients. But it’s definitely an interesting one to watch and it’ll be cool to see what happens as more and more human studies start coming out.