Over the past few years, public attitudes towards cannabis and its derivatives have changed drastically. In the commercial market, this translated into the development of countless CBD brands touting the wellness potential of the ingredient.
However, while consumers flock to purchase the newest products, from oils and skincare to chocolates and sparkling drinks, little evidence has emerged supporting the efficacy of these over-the-counter products.
In a recent review, published in Therapeutic Advances in Psychopharmacology, researchers aimed to address this issue.
What is CBD?
CBD, or cannabidiol, is a compound produced from the Cannabis plant. Studies have revealed that the compound is non-intoxicating, unlike tetrahydrocannabinol (THC) – another well-known cannabinoid – which has helped to strengthen the compound’s popularity across all age groups and demographics. However, it does have an effect on brain activity and some studies have found that it may have some subjective effects in very high doses.
In addition to its interactions with the human endocannabinoid system, CBD may also modulate a number of other neurotransmitter functions. Through these interactions, pharmaceutical-grade CBD has been found to reduce anxiety and psychotic symptoms. Other studies demonstrate that CBD may be beneficial in cases of addiction and childhood epilepsy, as well as being an anti-inflammatory.
Evidence for Over-the-Counter Products
The medicinal and therapeutic potential of CBD, demonstrated by these studies, has helped to bolster the sales of commercial products. It is estimated that 1 in 10 UK adults have now tried a CBD product. However, the authors of this review note that this popularity has been driven by studies that are based on pharmaceutical-grade cannabidiol and may not apply to the quantities commonly found in over-the-counter (OTC) CBD products.
OTC CBD products are overwhelmingly produced with hemp-derived CBD. The quantities of CBD used in these products tend to be far lower than those used in clinical trials. For example, in clinical trials, CBD doses may average at 1000mg per day. In contrast, CBD capsules and edibles average at 5 to 20mg per dose and oils from 2 to 8mg per dose. In addition, the maximum recommended dose tends to be below 30 mg/day.
Although the majority of clinical trials focused on CBD at doses considerably higher than in OTC preparations, at least eight randomised placebo-controlled clinical trials have assessed the effects of CBD at low doses.
The majority of these studies reported limited efficacy of CBD products and few adverse effects. However, one trial assessed the use of a CBD-prominent cannabis-based medical extract, as well as a THC-based medicine on multiple sclerosis-related spasticity and urinary symptoms. Some subjective outcomes were found to be improved, there was no evidence of an improvement to objective outcomes such as the Ashworth scale for spasticity and a walking test.
Low Doses of CBD and Psychotic and Anxiety Symptoms
CBD has gained attention for its ability to modulate the effects of psychotic symptoms. The researchers assessed the available evidence to determine whether this was also true in low doses.
Research has shown that CBD may reduce psychotic symptoms and cognitive impairments in regular cannabis users. This was partially observed in a small-scale experimental study in which volunteers were given a 5mg dose of intravenous CBD prior to a 1.25mg dose of intravenous THC. This study found that participants experienced a reduction in the severity of psychotic symptoms and anxiety.
These findings were mirrored in a larger sample study using an oral, rather than intravenous, CBD preparation. Pre-treatment with CBD (600mg) was seen to alleviate some psychotic symptoms and anxiety induced by THC (1.5mg). However, this study used a much higher dose of CBD – higher than typically found in OTC products – in comparison to THC.
Anxiety is among the most reported reasons for the use of CBD products. A survey of 2400 US medicinal cannabis users found that 66% of respondents used medicinal cannabis to manage anxiety.
A systematic review found that six randomised pre-clinical studies had focused on the efficacy of CBD for anxiety. One study administered doses of CBD (100, 300, 600mg) or placebo prior to the 60 participants completing a simulated public speaking test. In another study, 57 volunteers completed a similar test following the administration of either CBD (150, 300, 600mg) or placebo. Both of these studies found that only the 300mg dose reduced symptoms of anxiety. Doses of 100-150mg CBD had no effect, suggesting that OTC CBD products are unlikely to have a significant effect on anxiety.
Contents of OTC CBD Products
The quality of OTC CBD preparations is hugely variable, with many products currently taking advantage of limited regulation. For example, a US study of 84 CBD products sold online in 2016 found that only 31% (26) accurately reported the amount of CBD contained within. Similarly, a UK study revealed that only 38% (11/29) CBD products – sourced from online and the high street – contained within 10% of the advertised quantity of CBD.
The authors conclude that there is little evidence to suggest that OTC CBD preparations are significantly effective for the use as a pharmacological device. There is also little evidence that CBD in these doses has any health benefits. However, the researchers do concede that low levels of studies could play a role in these findings. More controlled trials are needed to determine the safety and efficacy of OTC CBD products. More accurate labeling and advertisement of OTC CBD products is also needed.