Cannabis Edibles and Cardiovascular Health: New Findings
It might seem like consuming a cannabis-infused brownie or gummy is a safer option compared to smoking. Yet, recent research implies that ingesting products containing tetrahydrocannabinol (THC) could negatively impact cardiovascular health over time, much like smoking cannabis itself.
According to the study, “chronic smokers of marijuana have poorly functioning blood vessels, akin to chronic tobacco smokers,” remarked Matt Springer, a cardiovascular researcher at the University of California, San Francisco (UCSF), who led the study. “THC edibles also seem to be linked to this issue.”
Published on May 28 in JAMA Cardiology, these results may challenge common misconceptions about the health consequences of cannabis.
“Many individuals consider marijuana to be completely harmless for heart health,” stated Dr. Robert Kloner, director of cardiovascular research at the Huntington Medical Research Institutes in Pasadena, California, who was not associated with this study.
While experts haven’t reached a definitive agreement on cannabis’s health effects, Kloner mentioned that the UCSF study adds to the growing body of evidence suggesting that marijuana may increase the risk of cardiovascular events, like heart attacks and strokes. This concern is particularly relevant for those with coronary artery disease or other risk factors, such as high blood pressure or diabetes, which could lead to artery narrowing.
Cannabis and Heart Health
To dive deeper into cannabis’s effects on heart health, Springer and his team enlisted 55 adult participants divided into three groups: cannabis smokers, THC edible users, and nonusers. They aimed to isolate the impact of consistent cannabis use, focusing on those who used it at least three times a week, strictly through their preferred method.
Dr. Leila Mohammadi, the study’s lead author and a physician-scientist at UCSF, acknowledged that the strict criteria for selecting participants resulted in a smaller sample size, which might limit the findings. However, it also allowed them to exclude other factors affecting blood vessel health, like tobacco use or pre-existing conditions.
To assess vascular function, researchers temporarily limited blood flow to the brachial artery—located in the upper arm—using an inflatable cuff while employing ultrasound to measure the artery’s diameter before and after releasing the pressure. This change is expressed as the percentage of dilation from the baseline measurement.
Springer indicated that this test provides insight into future heart health; if blood vessels fail to expand properly with increased blood flow, it correlates with a higher risk of negative cardiovascular outcomes, including heart attacks.
Among participants who did not use cannabis, the average vessel dilation was 10.4%. In contrast, cannabis smokers showed an average dilation of 6.0%, while edible users had only 4.6%. This reduction mirrors findings from a previous study involving chronic tobacco smokers.
The more cannabis someone used—measured by how often they smoked or the amount of THC consumed through edibles—the more pronounced their vascular impairment appeared.
To explore why cannabis might impact vascular function, researchers conducted a laboratory study assessing how participants’ blood samples affected endothelial cells, which line blood vessels and produce compounds that aid in vasodilation.
This dilation can be prompted by vascular endothelial growth factor (VEGF). However, when endothelial cells in lab dishes were exposed to blood from cannabis smokers, it inhibited VEGF-induced nitric oxide production. In contrast, blood from edible users and nonusers did not affect nitric oxide release, indicating that smoking and consuming THC might have different effects on the cardiovascular system. This aligns with a prior study that found even THC-stripped secondhand cannabis smoke affected the blood vessels of rats inhaling it.
The study primarily indicates a connection between cannabis use and vascular health, not definitive proof of causation. Additionally, a collaborator pointed out that while previous research suggested cannabis might harden blood vessel walls without affecting their dilation, the current findings report the opposite. This suggests more research is needed.
Springer highlighted that since they focused on habitual users, individuals who consume cannabis less frequently may experience different effects.
With cannabis increasingly legalized across states, access is on the rise. Yet, Kloner pointed out that research into the health effects of cannabis hasn’t kept pace. The continued federal prohibition of cannabis puts constraints on studies, making it a challenging topic to investigate.
