The cannabidiol CBD, which performs an opposing function to the element THC that is behind cannabis’ psychoactive effect, is growing in popularity across the globe. It is now used relatively widely to treat anxiety and other disorders, and is available in high-street stores throughout the UK. Scientific research has e In recent years, CBD oil has been called the 'miracle of the modern age'. But what is CBD, and can CBD products help the heart?
Does CBD Lower Resting Heart Rate?
The cannabidiol CBD, which performs an opposing function to the element THC that is behind cannabis’ psychoactive effect, is growing in popularity across the globe.
It is now used relatively widely to treat anxiety and other disorders, and is available in high-street stores throughout the UK.
Scientific research has established that CBD has many benefits, including lowering blood pressure and risk of suffering a stroke.
But there are several claims about other potential health reasons to take the product, and in some circles it has been suggested that the compound can decrease resting heart rate, so we’ve taken a look at the findings of studies over the years.
There’s certainly evidence that CBD can lower resting heart rate in stressful conditions, although it’s unclear if it has the same effect in non stressful circumstances or normal day-to-day life.
The research into this area goes back over a decade, with a study in 2009 finding that rats’ heart rate and blood pressure was decreased when they were exposed to a stressful situation and had been given a dose of CBD.
Then, two years later, researchers carried out a human study . They gave participants either a large dose of CBD or a placebo before a public-speaking event, and found that the group given CBD had lower blood pressure, heart rate, and anxiety levels.
However, a later study in 2017 found that CBD actually raised the resting heart rate of healthy males in normal conditions despite lowering blood pressure.
So although studies do indicate that CBD causes heart rate to remain lower when individuals are exposed to stressors, the evidence suggests it fails to decrease resting heart rate. Bear this in mind when you see claims the product can reduce heart rate.
CBD: What is it, and can it help the heart?
CBD is the latest health craze to sweep the high street, with claims it can help everything from chronic pain and inflammation to anxiety. But what is CBD, and can it really help the heart? Emily Ray finds out.
What is CBD, and is it legal in the UK?
CBD, or cannabidiol, is a chemical that’s extracted from the leaves and flowers of the cannabis plant. Cannabis itself is an illegal class B drug, as is the compound THC (tetrahydrocannabinol) which it contains. But pure CBD isn’t illegal, as it doesn’t cause the intoxicating effects of cannabis.
What CBD products are available?
The choice of CBD products has exploded recently: you can buy oils, capsules, muscle gels, sprays and oral drops, as well as beer, tea, sweets, hummus and even CBD-infused clothing.
Many of these can be easily picked up from reputable high street stores, such as Holland & Barrett or Boots.
Prices can be high: a 500mg bottle of CBD oil oral drops could set you back as much as £45. Not that this has put people off: over the past two years, sales of CBD have almost doubled in the UK, putting regular users at an estimated quarter of a million.
What is CBD used for?
A 2018 report by the World Health Organization suggested that CBD may help treat symptoms relating to conditions such as cancer, Parkinson’s disease, multiple sclerosis (MS), anxiety, depression, insomnia and Alzheimer’s disease.
However, it also notes that this research is still in the early stages, and that more studies are needed before conclusions can be drawn on whether CBD is effective.
CBD’s popularity has been given a boost by the fact that two CBD-containing medicines have been approved for prescription use by the NHS in England: Epidyolex, which has been found to reduce the number of seizures in children with severe epilepsy, and Sativex, which contains a mixture of CBD and THC, and is licensed for treatment of muscle stiffness and spasms in people with MS.
Does CBD work?
Harry Sumnall, Professor in Substance Use at Liverpool John Moores University, says: “In terms of the products found in shops, there’s virtually no evidence to support the claims made for a lot of them. There’s a lot of marketing that says CBD is a ‘miracle of the modern age’; however, the marketing has actually overtaken the evidence of what it’s effective for.”
“In terms of the products found in shops, there’s virtually no evidence to support the claims made for a lot of them.”
Harry Sumnall, Professor in Substance Use at Liverpool John Moores University
Professor Sumnall argues that while it could be effective for some people, in some of these cases the results could be caused by the placebo effect (where the patient’s belief in a treatment makes them feel better). The placebo effect can be powerful, but Professor Sumnall warns that if people try CBD oil instead of speaking to their doctor, it could cause a problem.
The biggest difference between CBD used in clinical trials and in stores is the dose. Research has shown that some products contain very little CBD (or even none at all). Others contain THC or other illegal drugs, or even alcohol instead of CBD. By contrast, in clinical trials the CBD is purified, manufactured to a very high standard and given at a much higher dose. It is also taken regularly and under medical supervision.
Since 2016, any CBD product that is presented as having medicinal value must be licensed and regulated as a medicine, regardless of whether it is actually effective. Manufacturers must follow very specific and robust rules around production, packaging and the information provided.
But so far, Professor Sumnall points out, CBD products in shops are marketed as food supplements, not medicines, so none of them have gone through this process.
Can CBD help the heart?
Inflammation is part of the process that leads to many diseases, including coronary heart disease, high blood pressure and stroke, and there is some evidence that CBD has anti-inflammatory properties. Other studies have suggested that CBD can have a protective effect on the heart: this has been proven in rats after a heart attack and in mice with some of the heart damage associated with diabetes. But because these studies are often based on findings in a lab or in animals, not in humans, we cannot yet be confident that CBD will benefit the human heart.
There is ongoing research into the use of purer forms of CBD for a variety of conditions, including heart and circulatory diseases and, in particular, diseases of the heart muscle, including myocarditis and some types of cardiomyopathy.
Some of this work is still in animals, and much more research is needed before we can definitively say that CBD can help in this area.
“It’s clear that CBD has potential,” says Professor Sumnall, “but we’re at a very early stage of that research.”
- Always talk to your doctor if you’re thinking about taking a CBD product to supplement your existing treatment.
Meet the expert
Harry Sumnall is a Professor in Substance Use at the Public Health Institute, Liverpool John Moores University. He was a member of the UK Government’s Advisory Council on the Misuse of Drugs between 2011 and 2019.