A new study has found that smoking marijuana and ingesting THC edibles over the long term can reduce blood vessel function at levels similar to those seen in cigarette smokers, posing a risk to heart health.
The growing legalization of cannabis use has led to an increase in studies investigating its effects. As more countries and states have legalized cannabis for medical or recreational use, researchers have had greater opportunities to study it in a more regulated, controlled, and accessible environment.
New research led by the University of California, San Francisco (UCSF) has looked at whether long-term cannabis use, either smoking marijuana or consuming THC edibles, affects heart health.
The researchers recruited 55 adults, comprising 20 females and 35 males, with a mean age of 31. They allocated them into three groups: marijuana smokers (three or more sessions a week for a year or longer), THC-edible users (three or more edibles a week for a year or longer), and non-users. The participants were otherwise healthy, and none used nicotine (either by smoking tobacco cigarettes or vaping) and were not frequently exposed to secondhand smoke. Blood and urine metabolites of THC, cannabidiol (CBD) and nicotine were measured, along with cholesterol levels, triglyceride levels, and body mass index (BMI).
To assess the participants’ blood vessel function, the researchers measured their arterial flow-mediated dilation (FMD) and carotid-femoral pulse wave velocity (PWV). FMD is a measure of how the arteries expand (dilate) in response to increased blood flow after that flow is temporarily restricted, usually by inflating a blood pressure cuff around the arm. A healthy artery will dilate more significantly, indicating that the endothelium, the inner lining of the blood vessel, is functioning well.
PWV measures how quickly blood moves through the arteries. Sensors are placed on the carotid artery in the neck and the femoral artery near the groin to measure how fast the pulse travels between these two points. PWV measures arterial stiffness. Healthy, flexible arteries will allow the pressure wave to travel slowly, but stiff arteries will cause it to travel faster. Both tests are valuable indicators of cardiovascular health and can help assess the risk of cardiovascular diseases like heart attack, high blood pressure, and heart failure.
In addition to these physiological tests of vascular health, the researchers also performed lab tests in which they exposed endothelial cells to participants’ blood to assess how it affected the cells’ production of nitric oxide (NO). NO causes blood vessels to dilate, allowing blood to flow more easily. Lower NO production can be a sign of poor endothelial function and a potential risk factor for cardiovascular problems.
Compared to non-users, arterial function (FMD) was found to be significantly worse in marijuana smokers and THC-edible users. Marijuana smokers had lower NO levels in the endothelial cells compared to non-users, suggesting that regular marijuana use could impair endothelial function and blood vessel health. On the other hand, THC-edible users didn’t show the same reduction in NO, indicating that different methods of cannabis consumption may affect vascular health in different ways.
“Chronic cannabis smoking and THC ingestion were associated with endothelial dysfunction similar to that observed in cigarette smokers, although apparently occurring via distinct mechanisms,” said the researchers. “This study enhances the understanding of the potential risks to vascular health linked to cannabis use and provides more evidence that cannabis use is not benign.”
Limitations of the study are that it could not account for different cannabis strains, and self-reported cannabis use can introduce recall bias.
The study was published in the journal JAMA Cardiology.
Source: UCSF
