What Are the Benefits of CBD?
More than 60 percent of CBD users were taking it for anxiety, according to a survey of 5,000 people. Does it help?
By Dawn MacKeen
The CBD industry is flourishing, conservatively projected to hit $16 billion in the United States by 2025. Already, the plant extract is being added to cheeseburgers, toothpicks and breath sprays. More than 60 percent of CBD users have taken it for anxiety, according to a survey of 5,000 people, conducted by the Brightfield Group, a cannabis market research firm. Chronic pain, insomnia and depression follow behind. Kim Kardashian West, for example, turned to the product when “freaking out” over the birth of her fourth baby. The professional golfer Bubba Watson drifts off to sleep with it. And Martha Stewart’s French bulldog partakes, too.
What is CBD?
Cannabidiol, or CBD, is the lesser-known child of the cannabis sativa plant; its more famous sibling, tetrahydrocannabinol, or THC, is the active ingredient in pot that catapults users’ “high.” With roots in Central Asia, the plant is believed to have been first used medicinally — or for rituals — around 750 B.C., though there are other estimates too.
Cannabidiol and THC are just two of the plant’s more than 100 cannabinoids. THC is psychoactive, and CBD may or may not be, which is a matter of debate. THC can increase anxiety; it is not clear what effect CBD is having, if any, in reducing it. THC can lead to addiction and cravings; CBD is being studied to help those in recovery.
Cannabis containing 0.3 percent or less of THC is hemp. Although last year’s Farm Bill legalized hemp under federal law, it also preserved the Food and Drug Administration’s oversight of products derived from cannabis.
What are the claims?
CBD is advertised as providing relief for anxiety, depression and post-traumatic stress disorder. It is also marketed to promote sleep. Part of CBD’s popularity is that it purports to be “nonpsychoactive,” and that consumers can reap health benefits from the plant without the high (or the midnight pizza munchies).
Just as hemp seedlings are sprouting up across the United States, so is the marketing. From oils and nasal sprays to lollipops and suppositories, it seems no place is too sacred for CBD. “It’s the monster that has taken over the room,” Dr. Brad Ingram, an associate professor of pediatrics at the University of Mississippi Medical Center, said about all the wild uses for CBD now. He is leading a clinical trial into administering CBD to children and teenagers with drug-resistant epilepsy.
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Does CBD work?
“It’s promising in a lot of different therapeutic avenues because it’s relatively safe,” said James MacKillop, co-director of McMaster University’s Michael G. DeGroote Center for Medicinal Cannabis Research in Hamilton, Ontario.
Last year, the F.D.A. approved Epidiolex, a purified CBD extract, to treat rare seizure disorders in patients 2 years or older after three randomized, double-blind and placebo-controlled clinical trials with 516 patients that showed the drug, taken along with other medications, helped to reduce seizures. These types of studies are the gold standard in medicine, in which participants are divided by chance, and neither the subject nor the investigator knows which group is taking the placebo or the medication.
While there is hope for treating other conditions with the plant extract, Epidiolex remains the only CBD-derived drug approved by the F.D.A. Most of the research on cannabidiol has been in animals, and its current popularity has outpaced science. “We don’t have the 101 course on CBD quite figured out yet,” said Ryan Vandrey, an associate professor of psychiatry and behavioral sciences at Johns Hopkins University School of Medicine.
Does CBD help anxiety and PTSD?
For students with generalized social anxiety, a four-minute talk, with minimal time to prepare, can be debilitating. Yet a small experiment in the journal Neuropsychopharmacology found that CBD seemed to reduce nervousness and cognitive impairment in patients with social anxiety in a simulated public speaking task.
However, a double-blind study found healthy volunteers administered CBD had little to no change in their emotional reaction to unpleasant images or words, compared to the placebo group. “If it’s a calming drug, it should change their responses to the stimuli,” said Harriet de Wit, co-author of the study and a professor in the University of Chicago’s department of psychiatry and behavioral neuroscience. “But it didn’t.”
Many soldiers return home haunted by war and PTSD and often avoid certain activities, places or people associated with their traumatic events. The Department of Veterans Affairs is funding its first study on CBD, pairing it with psychotherapy.
“Our top therapies attempt to break the association between reminders of the trauma and the fear response,” said Mallory Loflin, an assistant adjunct professor at the University of California, San Diego and the study’s principal investigator. “We think that CBD, at least in animal models, can help that process happen a lot faster.” While large clinical trials are underway, psychologists say there isn’t compelling evidence yet as to whether this is a viable treatment.
Does CBD help sleep and depression?
Up in the wee hours of the night, stuck watching videos of puppies? CBD may be promising as a sleep aid; one of the side effects of the Epidiolex trials for epilepsy was drowsiness, according to Mr. MacKillop, a co-author of a review on cannabinoids and sleep. “If you are looking for new treatments for sleep, that may be a clue,” he said.
But he cautions that the side effects could have been because of an interaction with other medications the children were taking to control the seizures. So far, there hasn’t been a randomized, placebo-controlled, double-blind trial (the gold standard) on sleep disorders and CBD.
A recent chart review of 72 psychiatric patients treated with CBD found that anxiety improved, but not sleep. “Over all, we did not find that it panned out as a useful treatment for sleep,” said Dr. Scott Shannon, assistant clinical professor of psychiatry at the University of Colorado, Denver and the lead author of the review in The Permanente Journal.
Sleep can be disrupted for many reasons, including depression. Rodents seemed to adapt better to stressful conditions and exhibited less depressive-like behavior after taking CBD, according to a review in Journal of Chemical Neuroanatomy. “Surprisingly, CBD seems to act faster than conventional antidepressants,” wrote one of the authors of a new review, Sâmia Joca, a fellow at the Aarhus Institute of Advanced Studies in Denmark and an associate professor at the University of São Paulo in Brazil, in an email interview. Of course, it’s difficult to detect depression in animals, but the studies that Ms. Joca and her colleagues reviewed suggested that in models of chronic stress exposure, the mice and rats treated with CBD were more resilient.
But without clinical trials in humans, psychologists say CBD’s effect on depression is still a hypothesis, and not an evidence-based treatment.
Is CBD harmful?
“If you take pure CBD, it’s pretty safe,” said Marcel Bonn-Miller, an adjunct assistant professor at the University of Pennsylvania’s Perelman School of Medicine. Side effects in the Epidiolex trial included diarrhea, sleepiness, fatigue, weakness, rash, decreased appetite and elevated liver enzymes. Also, the safe amount to consume in a day, or at all during pregnancy, is still not known.
Recently, the F.D.A. sent a warning letter to Curaleaf Inc. about its “unsubstantiated claims” that the plant extract treats a variety of conditions from pet anxiety and depression to cancer and opioid withdrawal. (In a statement, the company said that some of the products in question had been discontinued and that it was working with the F.D.A.)
Dr. Smita Das, chair of the American Psychiatric Association’s Council on Addiction Psychiatry’s cannabis work group, does not recommend CBD for anxiety, PTSD, sleep or depression. With patients turning to these to unproven products, she is worried that they may delay seeking appropriate mental health care: “I’m dually concerned with how exposure to CBD products can lead somebody into continuing to cannabis products.”
Some CBD products may contain unwanted surprises. Forensic toxicologists at Virginia Commonwealth University examined nine e-liquids advertised as being 100 percent natural CBD extracts. They found one with dextromethorphan, or DXM, used in over-the counter cough medications and considered addictive when abused; and four with a synthetic cannabinoid, sometimes called Spice, that can cause anxiety, psychosis, tachycardia and death, according to a study last year in Forensic Science International.
Earlier research found fewer than a third of 84 products studied contained the amount of CBD on their labels. Some users of CBD have also failed drug tests when the product contained more THC than indicated.
This year, 1,090 people have contacted poison control centers about CBD, according to the American Association of Poison Control Centers. Over a third are estimated to have received medical attention, and 46 were admitted into a critical care unit, possibly because of exposure to other products, or drug interactions. In addition, concern over 318 animals poured into the American Society for the Prevention of Cruelty to Animals’ Animal Poison Control Center.
Is CBD a scam or not?
A few drops of CBD oil in a mocha or smoothie are not likely to do anything, researchers contend. Doctors say another force may also be at play in people feeling good: the placebo effect. That’s when someone believes a drug is working and symptoms seem to improve.
“CBD is not a scam,” said Yasmin Hurd, director of the Addiction Institute of Mount Sinai in New York City who led a double-blind study of 42 recovering heroin addicts and found that CBD reduced both cravings and cue-based anxiety, both of which can cycle people back into using. “It has a potential medicinal value, but when we are putting it into mascara and putting it into tampons, for God’s sake, to me, that’s a scam.”
CBD products are everywhere. But do they work?
By now, you’ve probably run into a product containing cannabidiol, also known as CBD. It’s in everything from drinks and pet products to lotions and chewable gummies. Even major drugstore chains have announced they will start carrying CBD products in certain states.
But many people still don’t really know what CBD is. Is it marijuana? Is it legal? Does it actually work? Is it safe?
The answers to those questions aren’t necessarily straightforward. The only thing that is clear at this point: The marketing has gone way ahead of the science and the law when it comes to CBD products.
That said, CBD is thought to be a safe and effective option for certain conditions. Below, we sort through the confusion by answering some of the most common questions about CBD.
Is CBD marijuana?
Yes and no. Cannabidiol is one of the two best-known active compounds derived from the marijuana plant. The other is tetrahydrocannabinol, or THC, which is the substance that that produces the “high” from marijuana.
CBD does not get you high, but the idea that it’s not psychoactive is something of a misconception in his opinion. It does change your consciousness. You may feel mellow, experience less pain, and be more comfortable. In addition, some CBD products do contain small amounts of THC.
While CBD can come from marijuana, it can also be derived from hemp. Hemp is a related plant with 0.3% or less of THC. This plant is often used to make fabrics and ropes. As of 2018, Congress made hemp legal in all 50 states, and consequently CBD derived from hemp is also legal. The rules around marijuana-derived CBD, however, are far less clear.
Is marijuana-derived CBD legal?
Again, yes and no, depending on where you live. In some states marijuana is legal for both recreational use and medical use. In other states, it’s legal only for medical use. And in some areas, it’s not legal at all.
When it comes to CBD products, the FDA is still trying to get its arms around the issue. The agency is just starting the process of hashing out some rules regarding CBD sales. Officials recently formed a working group to create guidelines that could allow companies to legally market CBD products. Currently, CBD products are considered supplements, which aren’t FDA-regulated, and it is illegal for companies to make health or therapeutic claims about the products in their marketing. In announcing its effort to set CBD marketing rules, the FDA also signaled that it is cracking down on CBD companies that are using “egregious and unfounded claims” to market their products to “vulnerable populations.”
Currently, there is only one CBD product that has FDA approval: a prescription medication called Epidiolex, used to treat some rare severe seizure disorders in children. The bottom line is that in order to understand whether CBD is legal where you live, you’ll need to consult your state health department website or professionals in your community.
Does CBD work?
Yes, there is evidence that CBD works for some conditions, but certainly not all the conditions it is being promoted for these days. There’s no evidence, for example, that CBD cures cancer. There is moderate evidence that CBD can improve sleep disorders, fibromyalgia pain, muscle spasticity related to multiple sclerosis, and anxiety.
People report that oral CBD helps relieve anxiety and pain and also leads to better sleep. However, the same may not be true for a host of other CBD products on the market today, in particular those that are rubbed on the skin. It’s hard to know whether these have any clinical benefit, because they haven’t been tested sufficiently.
Testing also shows that many products don’t contain what’s claimed on the label. For example, they may have less CBD than advertised. So, buyer beware.
Where should you purchase CBD products?
If you are interested in trying a CBD product, it’s best to seek one through a dispensary, which is an establishment legally licensed to sell marijuana, if they are available in your state. Dispensary products must be labeled so you can see exactly how much CBD is in the product and whether it also contains THC. A small amount of THC in a CBD product isn’t typically problematic. But larger amounts could cause a “high” and may present a risk if you are going to drive.
Also, keep in mind that CBD products aren’t standardized and will vary. It helps to keep a journal recording what type of CBD product you took, how much, and your response to it. This will help you track what works and what doesn’t for your condition.
Is CBD safe?
The safest way to take CBD is orally, as a tablet, chewable, or tincture (a concentrated liquid typically administered with a dropper). Steer clear of any illegally sold synthetic CBD products, sometimes called “spice” or “bath salts.” These products have induced psychotic reactions in some people and pose a major health risk.
For adults, CBD appears to be a very safe product. CBD does produce side effects for some people, including nausea, fatigue, and irritability. It may also interact with certain medications, so always check with your doctor before use.
But for children under age 21 it’s a different story. It’s also not clear if any amount of CBD is appropriate for children.
Evidence regarding CBD is still building. Now that some states have legalized recreational and medical use of marijuana products, including CBD, scientists are finding it easier to conduct research. More will be known in the next 5 to 10 years, including whether there are yet undiscovered problems associated with long-term use.
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The reality behind cannabidiol’s medical hype
Michael Eisenstein is a freelance writer in Philadelphia, Pennsylvania.
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Cannabidiol oil has purported health benefits, including helping to relieve chronic pain. Credit: Don Bartletti/Los Angeles Times/Getty
Cannabidiol (CBD) is an illegal drug with no redeeming value. It is also a useful prescription medicine for epilepsy, with considerable potential for treating numerous other conditions. And it is a natural dietary supplement or ‘nutraceutical’ with countless evangelists in the health and wellness community. Although contradictory, all three statements are true from different perspectives, and clinical researchers are frustrated.
“In New York City, you can go to a latte shop and get a CBD product, but if I want to do a clinical trial, I’ve got to get a 2,000-pound safe and go through six months of paperwork and licensing,” says Orrin Devinsky, director of the NYU Langone Comprehensive Epilepsy Center in New York City. Like the cannabis plant from which it is derived, CBD, a type of cannabinoid, is classified by the US Drug Enforcement Administration in the same way as are heroin and lysergic acid diethylamide (LSD) — schedule 1 substances with “high potential for abuse” and “no currently accepted medical use”.
Part of Nature Outlook: Cannabis
This flies in the face of current evidence. Numerous studies have shown that CBD is a safe and non-habit-forming substance that does not produce the ‘high’ associated with tetrahydrocannabinol (THC), the main psychoactive component of cannabis 1 . In 2018, the US Food and Drug Administration (FDA) determined that Epidiolex — a purified CBD product developed by GW Pharmaceuticals in Histon, UK — effectively reduces the frequency of seizures in certain rare forms of paediatric epilepsy. This approval has heartened the cannabinoid research community, which has long recognized the medicinal potential of CBD but come up against scepticism and regulatory constraints on the road to the clinic.
But at the same time, the many manufacturers that promote CBD-laden oils, lotions and foods as a panacea for various health issues, often with minimal regard for local laws or medical evidence, are putting CBD’s medical advocates in an uncomfortable position. “I get calls and e-mails all the time — not just from families, but from physicians who have no clue how to address the requests they get from patients,” says Yasmin Hurd, director of the Addiction Institute of Mount Sinai in New York City. “It’s a real problem.”
Stuck in the weeds
The breakthrough approval of Epidiolex was driven by strong investment from GW Pharmaceuticals, as well as vigorous advocacy from families of children with epilepsy who had heard tantalizing anecdotes about CBD’s effects from jurisdictions in which medical cannabis is legal. “About eight years ago, a patient’s father said he was hearing stories about families in Colorado and California who use high-CBD strains for their kids’ epilepsy,” says Devinsky. “He asked me to do a trial.” As a medical student, he had been taught the history of medicinal cannabis, including well-documented uses of the plant by nineteenth-century physicians to treat seizures. Indeed, cannabis has been part of the clinical armamentarium for epilepsy for more than 4,000 years.
Research on CBD in the 1970s and 1980s focused on its interplay with other cannabinoids, and particularly THC. “Whereas THC can induce psychotic symptoms, impair cognition and make people anxious, CBD appears to do the opposite,” says Philip McGuire, a psychiatrist at King’s College London.
The first clues that CBD might suppress epileptic episodes came from a small clinical trial 2 in 1980. It was led by Raphael Mechoulam, a chemist at the Hebrew University of Jerusalem, whose work on the synthesis and biochemical characterization of cannabinoids in the 1970s had led researchers to begin to explore the medicinal properties of CBD. A number of other trials that explored the compound’s pharmaceutical properties followed, although scientists conducting early forays into CBD clinical research faced an uphill battle. F. Markus Leweke, a psychiatrist who specializes in mental illness at Sydney Medical School, Australia, recalls struggling for seven years to publish findings from a randomized controlled trial that demonstrated that CBD might offer an effective treatment for psychotic symptoms in schizophrenia 3 . “We got about 15 rejection letters,” says Leweke. “And this is a paper that has since been cited almost 500 times.”
Claims about the health benefits of cannabis are often overstated and lack supporting evidence. Credit: Rodger Bosch/AFP/Getty
Forty years on from Mechoulam’s initial work, extensive randomized controlled trials have decisively shown that this purified cannabinoid can profoundly benefit children with certain epileptic disorders. “Over those trials, we saw about a 26–28% reduction in frequency over placebo in all convulsive seizures for Dravet syndrome and drop seizures for Lennox–Gastaut syndrome,” says Devinsky, who has led several such studies 4 , 5 . “Some of the patients became, and remain, seizure-free.”
Preclinical data from rodent and cell-culture studies have hinted at the possible benefits of using CBD to help treat disorders that range from Parkinson’s disease to chronic pain. The range of conditions in which CBD is being tested might seem diverse, but it is a compound with far-reaching, if poorly understood, physiological effects. Antonio Zuardi, a psychiatrist at the University of São Paulo in Brazil, notes that something on the order of 20 possible mechanisms of action have been described to date for CBD. “These multiple pharmacological effects may justify the wide range of possible therapeutic activities.”
The mechanism of CBD’s action on cannabinoid receptors, at least, is well understood. CBD can bind to the cannabinoid receptor CB1, which is the same receptor that THC seeks out in the brain. Unlike THC, however, CBD restrains rather than activates CB1 signalling, and therefore doesn’t induce the psychoactive effects of its cannabinoid cousin.
But CBD wears many hats. It seems to mediate its antiepileptic effects by binding to a protein called GPR55, which can otherwise trigger the onset of seizures by promoting the hyperactivation of neurons 6 . In addition, CBD acts on receptors that mediate pain signalling and inflammation, as well as at least one receptor for the neurotransmitter serotonin, 5-HT1A 7 . Gabriella Gobbi, a psychiatrist and neuroscientist at McGill University in Montreal, Canada, has found that CBD’s physiological effect on the brain resembles that of selective serotonin reuptake inhibitor (SSRI) drugs 8 , which are used to treat clinical depression. “After a few days, you get this desensitization of 5-HT1A, like you would with an SSRI, and increased serotonin signalling,” she says. Further experiments in rats failed to capture an antidepressant effect, but her team found that CBD-mediated modulation of 5-HT1A could relieve neuropathic pain in the animals.
Beyond epilepsy, clinical data to support the medicinal benefits of CBD are more limited, mainly due to the small scale and inconsistent design of trials. “We have very few double-blind, randomized placebo-controlled trials,” says Gobbi. But exciting progress is being made towards treating several conditions.
Psychosis — particularly in the context of schizophrenia — is one such area of promise. In 1995, Zuardi and Mechoulam reported the case of a person with schizophrenia who experienced meaningful relief from their symptoms when treated with high doses of CBD 9 . Several subsequent small-scale clinical studies detected similar hints of efficacy. In their groundbreaking trial 3 , Leweke and his colleagues put the compound through a particularly rigorous test by comparing its effects with those of amisulpride, a potent medication for schizophrenia. “We saw a significant decrease in symptoms over time for both compounds, and CBD beat amisulpride in terms of side effects, by far,” Leweke says. The team also found a clue to the mechanism by which CBD might exert its antipsychotic effects: treatment with CBD was associated with elevated levels of anandamide, a cannabinoid produced by the body that seems to offer protection from psychosis.
McGuire and his colleagues conducted a randomized controlled trial that showed that CBD can have an additive effect when used with conventional antipsychotic drugs 10 . Together, they were better able to control symptoms such as hallucinations and delusions than could conventional medication alone. His team has received funding for a large, international trial to test whether CBD can be developed as a licensed medicine for treating psychosis.
Anxiety disorders are another mental-health condition that CBD has been shown to help alleviate. Zuardi and his colleagues used a test that simulates speaking in public to show that pretreatment with a single dose of CBD can reduce the associated discomfort in people with social anxiety disorder 11 . A similar effect has been observed in healthy people in anxiety-inducing situations 12 , and several researchers are exploring CBD as a means of soothing social stress in people with autism spectrum disorder. Devinsky notes that many of his patients with epilepsy have also been diagnosed with autism spectrum disorder, and he is involved in two clinical trials that aim to test whether CBD can meaningfully reduce the irritability and anxiety of those with autism. “Many parents wanted to keep their children on it even if the seizures didn’t improve, because they’re calmer and sleeping better,” he says.
And although cannabis been demonized as a gateway to more dangerous substances, Hurd has found that it might actually contain an effective antidote for potentially deadly addictions. After observing that rats with a heroin addiction were less likely to seek out the opioid when treated with CBD, she began to investigate whether CBD might have the same effect on people with an opioid dependency. On the basis of an encouraging pilot study, Hurd and her team conducted a randomized controlled trial in 42 abstinent heroin users, who had avoided taking the drug for up to three months after years of routine or heavy use 13 . The researchers then exposed the participants to drug paraphernalia and videos that showed heroin use — cues that normally provoke strong cravings in people with a dependency — and then measured participant-reported responses and physiological indicators of stress and anxiety. “Cue-induced craving is associated with increased cortisol levels and increased heart-rate, and CBD reduced those,” she says. Participants receiving CBD also reported lower levels of drug craving and anxiety relative to placebo group, and Hurd notes that the beneficial effects persisted for a week after the final administration of CBD.
A difficult delivery
Despite its promise, CBD’s impact as a drug has been mixed. Importantly, it is relatively safe. The side effects most commonly associated with a high dose of Epidiolex include digestive problems, rash and drowsiness, as well as the potential for liver damage in patients taking certain other medications. For example, Devinsky notes that patients who are receiving valproic acid to treat seizures or migraines might be at an elevated risk. But in many of the CBD trials conducted so far — particularly in the realm of antipsychotic drugs, which are known for their strong side effects — CBD has proved more tolerable than existing alternatives. “The side effects weren’t significantly worse than with placebo,” says McGuire of his 2018 study of CBD in people with schizophrenia 10 .
This is important because people typically require large doses of the drug to experience a clinical benefit — in many studies, the doses used are as high as 1 gram or more. This is because CBD is poorly absorbed by the body, with most of every dose being excreted before it can take effect. “If you take it orally, the bioavailability is in the range of 4–6%, which is terrible,” says Devinsky. “If you take it after a fatty meal, you can get that up to 16–20%.” Zuardi notes that his group routinely observes a bell-shaped dose–response curve for CBD. For example, whereas 300 milligrams of CBD might reduce a person’s anxiety, the same person might not get any relief from a dose of either 100 milligrams or 900 milligrams. To complicate matters further, this sweet spot for CBD dosing can differ not only between symptoms, but also between patients.
Campaigners show support for legalizing cannabis for medical use in Atlanta, Georgia. Credit: Erik S. Lesser/EPA/Shutterstock
This is one of several reasons why researchers caution against self-medication with CBD products targeted at consumers. CBD is available in shops worldwide, but the legality of such sales varies widely. In Canada, selling cannabis and its derivatives is legal, whereas the European Union authorizes the sale of CBD derived from hemp (low-THC varieties of cannabis) but not from marijuana (high-THC cannabis). In the United States, the latest Farm Bill, which was enacted in 2018, potentially legalizes the production of CBD from hemp under certain conditions — although the sale of CBD products generally remains ostensibly illegal. Regardless of the legal situation at the federal level, CBD commercialization remains something of a free-for-all in the United States — individual states are making their own laws, and the FDA has taken only limited action to enforce federal laws on CBD. “They’ve sent some notices to companies that have made medical claims, but that’s about it,” says Marcel Bonn-Miller, a psychologist at the University of Pennsylvania, Philadelphia, and global scientific director at Canopy Growth Corporation, a cannabis company in Smiths Falls, Canada. (An FDA spokesperson responded that the agency “is working quickly to continue to clarify our regulatory authority over products containing cannabis and cannabis-derived compounds like CBD”.)
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Many such claims lie beyond the bounds of medical evidence — including that regarding CBD preparations that purport to prevent cancer or to treat Alzheimer’s disease. However, even products that make more modest claims could be problematic. In 2017, Bonn-Miller and his colleagues performed chemical analyses on 84 products purchased online from 31 companies, and found that only 31% were accurately labelled with regard to CBD content 14 . What’s more, many commercially available preparations have been found to be contaminated with intoxicating doses of THC, heavy metals and pesticides, as well as toxic solvents from the CBD extraction process. In a case reported by the US Centers for Disease Control and Prevention, up to 52 people in Utah became seriously ill or were hospitalized after using a CBD oil that contained an intoxicating synthetic cannabinoid drug. The possibility of such contamination is concerning to all potential users, and especially to people who are seeking relief from the effects of a health condition. “It’s one thing if you’ve got too much THC in gummy bears you’re using with friends, but something entirely different if it’s a kid you’re giving CBD for medical reasons,” says Bonn-Miller. “I don’t trust any CBD product until I’ve done the tests.”
Between two worlds
The regulatory disconnect that surrounds CBD creates an odd situation in which the public can self-medicate using a potentially questionable product, while scientists face a struggle to perform high-quality clinical trials. “The fact that CBD remains schedule 1 in the United States is unconscionable,” says Devinsky. That restrictive classification, he says, “is impairing research”.
Obtaining sufficient quantities of pharmaceutical-grade CBD to conduct a well-powered clinical trial is already difficult. “It’s extremely expensive,” says Leweke. “You need about one gram a day, and the list price is about 60 euros [US$67] per gram.” This is because the process of extracting CBD from the cannabis plant is complex and arduous — and when the goal is to obtain CBD for use in people, the substance must meet the high bar set for clinical-grade preparations, under which only minimal quantities of THC or other contaminants are permissible. Several companies have developed strategies for manufacturing fully synthetic CBD, an approach that essentially eliminates concerns about purity. But synthetic CBD still falls under the schedule 1 classification in the United States, which creates extra economic and bureaucratic hurdles for clinical trials. Even in Canada, where recreational cannabis has been legalized, Gobbi describes a complex application process and a more than six-month wait to obtain government authorization to conduct a CBD study in people or animals.
Unfortunately, if studies such as these are not done — or not done properly — then consumers will be left to fend for themselves in a poorly monitored marketplace. In that scenario, the signal of true clinical benefit would almost certainly be drowned out by the noise from personal anecdotes and the placebo effect, which could jeopardize the future of a potentially valuable medicine. “Humans are notoriously bad when they think they see patterns,” says Devinsky. “When everyone is convinced that they’re right with no data, I call that religion — and CBD is currently religion for the average person.”
Nature 572, S2-S4 (2019)
This article is part of Nature Outlook: Cannabis, an editorially independent supplement produced with the financial support of third parties. About this content.
Updates & Corrections
Correction 23 July 2020: An earlier version of this Outlook article misquoted Gabriella Gobbi. She said that 5-HT1A is desensitized in response to cannabidiol, not sensitized.
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