No good evidence that ‘banned’ substances reliably destroy cancer cells in humans

A misleading post that was widely shared in 2015 is recirculating on X (formerly Twitter). The post claims that cannabis oil and “vitamin B17” destroy cancer cells. It goes on to say that both substances have been banned by the US Food and Drug Administration (FDA) and that this needs to be explained.

Posts with a similar message were previously shared on Facebook and Instagram, and we’ve seen a couple of recent examples on Instagram which now appear to have been deleted.

It is true that cannabis oil is not licensed for medical use in the US by the FDA. 

It is also true that ‘vitamin’ B17 has been banned for several decades by the FDA. 

However, the claims about these substances’ ability to destroy cancer cells are not entirely accurate and require some context. Even if some studies do show cells dying in the lab, this does not always mean the same would happen if a person was treated with the same substance.

Whilst there are some health benefits associated with some components of cannabis, there is limited evidence that it destroys cancer cells and not enough research to show whether this would translate into an effective treatment.

Furthermore, ‘vitamin’ B17 has not been shown to reliably destroy cancer cells in humans and it can be poisonous. We have written about similar claims previously.

Inaccurate health information can affect health decisions and has the potential to cause harm.

Cannabis and cannabis oil

There are many varieties of cannabis, which contain hundreds of compounds. The cannabis plant contains several active substances (cannabinoids), the main ones being cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC). 

Cannabis can have many different effects on the brain and body. Short-term effects include altered senses and difficulties with memory and problem solving. Longer-term effects include irritability and sleep disturbance. Chronic cannabis use can lead to drug dependence and can also have negative effects on mental health.

Cannabis is illegal in the UK, but the Misuse of Drugs Regulations were amended in 2018 to allow the use of cannabis-derived products for medicinal purposes. Different cannabinoids (medical cannabis) can be prescribed by specialists if other treatments have not helped or are unsuitable. 

Medical cannabis is currently available for some conditions. For example Epidyolex (pure CBD solution) is licensed for rare forms of severe epilepsy. Other cannabinoids are licensed for multiple sclerosis, chronic pain and nausea and vomiting secondary to chemotherapy.

Unlike CBD oil, which is made from the flowers of the cannabis plant and does not normally contain THC, cannabis oil is made from the flowers, leaves and stalks of the cannabis plant. It contains THC, which is the substance that causes the ‘high’, or psychoactive effects. Cannabis oil is often found in liquid form and made into a capsule or used with a dropper. It can be dissolved or diluted in a carrier oil.

The NHS says that further research is required to better understand the long-term risks of products that contain THC before they can be used in a medical setting.

The FDA, which is responsible for regulating and approving medications in the US, holds a similar opinion, that further research is required before some cannabis-based products are approved for medical settings.

To date, the FDA has only approved four medicinal products that are either related to or derived from cannabis, but this does not include cannabis oil.

What is ‘vitamin B17’?

‘Vitamin B17’, also known as amygdalin, is a naturally occurring substance found in the stones of some fruits, raw nuts and other plants. The synthetic form is known as Laetrile.

As with some minerals, vitamins are nutrients that the body needs to remain in good health. Although amygdalin is commonly referred to as ‘vitamin B17’, this is not accurate as it is not considered to be a real vitamin.

Additionally, there are concerns regarding its potential toxicity, because it is metabolised to cyanide after being taken orally. Cyanide toxicity can cause breathing difficulties and heart rate changes. If untreated it can rapidly progress to coma, seizures and death.

Cell death and cancer

Cells can die via different mechanisms. One such mechanism is called apoptosis, which is a method the body can use to get rid of cells it does not need or which are abnormal in some way.

The development of cancer requires various steps that include genetic changes and processes that control cell growth and function to become deregulated. Due to the complexity of cell death mechanisms, inducing cells to die via one process may not translate to something that is medically effective for a patient.

Cancer cells have various properties that are different to normal cells and they do not always behave like normal cells. Amongst other things, cancer cells tend to be resistant to dying. 

Scientists have observed that, in some cases, apoptosis can actually promote tumour development. This is thought to be because part of the body’s natural function is to try to replace damaged cells and when cells die in this way they can be replaced by cells that have abnormal characteristics.

Cannabis and cancer

Different types of cannabinoids have been used to treat conditions such as nausea and vomiting in the advanced stages of illnesses like cancer for many years in the US. There is also ongoing research into the effectiveness of these substances for other conditions.

Cannabis has not been approved as a treatment for cancer in the US. Although there is no specific legal restriction for this in the UK, current scientific evidence only supports treatment of the conditions mentioned above.

Scientific studies into whether cannabinoids can treat cancer in humans are quite limited and have shown mixed results. 

Animal and lab-based studies have suggested that THC has some effect on tumour cells where the apoptotic mechanism of cell death was observed in nerve cells. A human study looking at the effect of THC on a type of brain tumour in a small group of patients found an association between THC and reduced tumour growth. 

Whilst research has shown that some cannabinoids can have an effect on the lifespan of some tumour cells, others have found that they may encourage some cancers to grow. 

The American Cancer Society says that while ongoing early clinical research shows that some cannabinoids can be safe to use, they have not yet been shown to cure or help to control cancer. It cautions against relying on cannabis alone as a treatment for cancer.

Further research is required to improve understanding of the specific effects of each cannabinoid on different cancers and how they interact with existing cancer treatments.

Importantly, there have been no studies on the effects of cannabis oil in people, and existing studies on cannabinoids have not yet shown them to cure or control cancer.

Amygdalin and cancer

Amygdalin has been promoted as an alternative cancer treatment and used for many years but there is not enough reliable evidence for its use as an effective anti-cancer drug. 

Lab-based studies have suggested that amygdalin induces apoptosis and has other effects on the cell cycle. A study on cervical cancer cells has also suggested that amygdalin is effective via the apoptotic mechanism.

However, the National Cancer Institute carried out studies in rodents and found that amygdalin did not improve survival or cause a response in the various tumours tested. They also looked at whether combining amygdalin with another medication could be beneficial and similarly found no response.

Amygdalin has not been shown to be effective against cancer in human studies. There is no reliable evidence that it is an effective treatment for cancer. 

There have been no randomised controlled trials and claims that amygdalin can be used as a cancer treatment are not backed up by scientific data. 

Amygdalin is not approved for use in either the US or the UK as a treatment for cancer.