CBD, or cannabidiol, is one of numerous compounds know as cannabinoids found in cannabis or hemp plants. It lacks the psychoactive effects of the most common cannabinoid, THC, so doesn’t produce the ‘high’ associated with marijuana.
CBD is sold in a variety of forms, including bottled oil, vaping liquids, chewable gummies, capsules and creams, and is an increasingly popular natural remedy for a whole range of conditions.
Research into the potential benefits of CBD has shown promising results in a number of areas. Together with its low level of significant side-effects, this makes it of continuing interest to medical science.
Can CBD help with cancer?
There is good evidence that CBD and other cannabinoids can help to relieve some cancer-related symptoms, including chronic pain and nausea. Early laboratory studies into CBD’s effect on cancer cells including breast cancer and colon cancer are also encouraging, showing that in some situations CBD can cause the death of cancer cells, reduce their spread and block the growth of tumours.
It’s important to remember that results demonstrated in test tube and animal studies may not be replicated in humans. However, the potential use of CBD to treat cancer is certainly an area where further research is warranted.
How CBD can help cancer-related symptoms
One of the most common cancer symptoms is chronic pain and a number of studies have shown that CBD may have a therapeutic effect on this, especially when given alongside another cannabinoid, THC.
One study of 177 cancer patients, and a follow-up project, found that a combination of the two compounds boosted pain relief in subjects whose traditional opioid treatments had been insufficient. It also showed that CBD and THC taken together led to greater improvement than THC alone and suggested that CBD may help temper the potential unwanted psychoactive side-effects of THC.
A review of 18 trials on cancer patients agreed that a combination of CBD and THC “demonstrated a significant analgesic [pain-killing] effect of cannabinoids”.
The drug Nabiximols, marketed under the trade name Sativex, also contains CBD and THC, along with other cannabinoids. Originally prescribed to combat spasticity – muscle-stiffening – in multiple sclerosis patients, it has since been approved in Canada to help improve pain relief in both MS and cancer sufferers. The US Food and Drugs Administration is also investigating Sativex for the same purpose.
As well as the symptoms associated with cancer itself, patients often find themselves dealing with the adverse side-effects of traditional anti-cancer treatments.
A study published in the British Journal of Clinical Pharmacology showed that a combination of CBD and THC alongside existing anti-nausea medication was able to further reduce nausea and vomiting caused by chemotherapy.
Can CBD help against cancer?
A number of test tube and animal-based studies have built up good initial evidence that CBD and other cannabinoids have anti-cancer qualities, including reduction in the growth and spread of tumours across a range of different cancers.
While it’s important to point out that these studies come with no guarantee that similar results can be replicated in human cancer patients, they do provide encouragement for further study.
Researchers have done initial research focused on breast cancer cells in both test tube and animal environments.
One test tube study investigated the mechanisms by which CBD induced the death of breast cancer cells, highlighting the value of further study into CBD’s potential as an anti-tumour agent.
A trial using mice showed that CBD decreased the effect of a protein that influences metastasis – the spread of cancer cells and further tumour growth around the body – in breast cancer.
A follow-up study, using test tube and animal techniques, showed that CBD inhibited human breast cancer cell proliferation and significantly reduced the size of tumour mass, concluding “The results have the potential to lead to the development of novel non-toxic compounds for the treatment of breast cancer metastasis”.
A report published in the Journal of Pancreatic Cancer reviewed a number of test tube and animal model studies that had used CBD and THC to treat pancreatic cancer cells.
It found that animal models “consistently demonstrated tumour growth-inhibiting effects”. The review concluded that these cannabinoids could be an effective supplementary treatment for pancreatic cancer but noted that evidence from human clinical trials was lacking.
A large-scale study published online in 2014 looked at the association between smoking tobacco, smoking cannabis and the risk of developing bladder cancer. It found that smoking tobacco alone was associated with an increased risk of bladder cancer but cannabis use alone was associated with a 45% reduction in bladder cancer incidence.
The study noted that a cause-and-effect relationship between cannabis use and reduced risk of bladder cancer had not been established but concluded that “cannabis use may be inversely associated with bladder cancer risk in this population”.
However, the study did not involve research that isolated the possible effects of different cannabinoids so it’s impossible to know whether CBD itself was involved in any interactions.
An animal study using a strain of cannabis with high CBD content, as well as pure CBD, showed that both reduced the spread of colon cancer cells but not healthy cells. The high-CBD cannabis also reduced the incidence of the lesions and polyps that can later lead to colon cancer.
The study didn’t draw any hard conclusions about whether such treatment would work in human patients but did say “the results may have some clinical relevance for the use of Cannabis-based medicines in cancer patients.”
Gliomas are the most common type of malignant brain tumour. A review of animal and test tube studies into the effect of cannabinoids on glioma cells found that every trial showed evidence of anti-tumour effects, including reduction in tumour size and spread, and the death of cancer cells. It also showed that normal cells were not affected. It concluded “these findings indicate that cannabinoids are promising compounds for the treatment of gliomas”.
What Cancer charities say about CBD oil
Cancer charities are of course quick to point out the limit of what is currently known about the effects of CBD and other cannabinoids on cancer, and the lack of human trials. However, they do recognise positive signs from existing research.
Cancer UK says “Cannabinoids have helped with sickness and pain in some people”, adding that studies have shown that “different cannabinoids can cause [cancer] cell death, block cell growth, stop the development of blood vessels needed for tumours to grow, reduce inflammation [and] reduce the ability of cancers to spread.
But the charity also notes that “cannabinoids can sometimes encourage cancer cells to grow [and] cause damage to blood vessels”.
Macmillan Cancer Support references anecdotal evidence of the benefits of CBD but is clear that this is not the same as clinical evidence.
“There are a number of examples where people say that using CBD oil has had a dramatic effect on their health. But these are individual stories and not based on clinical research trials.
“If you are thinking of using CBD oil, we suggest you talk to your healthcare team.”
What are the side-effects of CBD oil? Is it safe?
CBD oil is well known both by users and researchers for its low level of serious side-effects, making it a good prospective alternative to traditional medications which may have adverse effects including possible dependency. Among clinicians, CBD is considered ‘well tolerated’, meaning that very few participants drop out of experimental trials due to its effects.
Both the Court of Justice of the European Union and the World Health Organisation, meanwhile, are now clear that there is no evidence to suggest that CBD represents any threat to public health.
Nevertheless, CBD does have some notable side-effects. The most common is dry mouth, experienced by 11% of users, according to a 2018 study, followed by increased appetite (6%), red eyes (less than 3%) and drowsiness (less than 2%). CBD can also sometimes cause nausea and diarrhoea.
As a precaution, the UK Food Standards Agency advises that pregnant and breastfeeding women and those taking medication do not use CBD and that healthy adults refrain from taking more than 70mg a day (around 28 drops of 5% strength CBD oil), unless advised by a doctor.
What’s the best way to take CBD?
CBD products come in a variety of formats, including chewable gummy sweets, capsules, e-juices used in vaping devices and bottled oils, usually with in-built droppers, that can be taken directly by mouth or added to food and drink.
While vaping is the fastest and most efficient method of taking CBD, inhalation is not for everyone and the jury is still out on the safety of vaping itself. CBD oil therefore offers the best alternative, especially if taken sublingually – that is, under the tongue.
Placing droplets of CBD oil beneath the tongue and leaving them there for a minute or two before swallowing allows the CBD to permeate the blood vessel-rich membrane and quickly enter the bloodstream.
Swallowing CBD oil directly or adding it to food and drink is likely to be less effective because digestive processes will destroy some of the active ingredient and it will take longer to enter the bloodstream. The degree of absorption can also depend on the kind of food you have eaten, while there is some evidence that CBD may start to degrade when in solutions above a certain temperature, meaning you could lose out if you add it to your morning coffee.
What is the best CBD oil?
It’s important to choose a trustworthy brand of CBD oil. Recent research by industry body the Centre for Medical Cannabis showed that the reliability of CBD products can vary hugely, with many of those tested on the UK market containing less than 50% of the amount of CBD claimed on the label and one high street product containing no CBD at all.
Jersey Hemp is the first company in the British Isles granted a licence to harvest its own hemp for CBD production. Unlike some brands that source the cheapest possible hemp from abroad, it is therefore able to guarantee the quality and provenance of its raw ingredients, while independent laboratory tests show exactly how much CBD is present in each batch.
The Centre for Medical Cannabis called Jersey Hemp CBD oil “one of the most compliant, high quality and accurately labelled products that we tested.”