29 May Smoking Marijuana, or Using Edibles, May Not Avoid Harmful Vascular Side Effects of Tobacco
MedicalResearch.com Interview with:
Dr. Springer
Matthew L. Springer, Ph.D.
Associate Professor of Medicine
Division of Cardiology
Cardiovascular Research Institute
Broad Center of Regeneration Medicine and Stem Cell Research
Center for Tobacco Control Research & Education
Helen Diller Family Comprehensive Cancer Center
University of California, San Francisco
MedicalResearch.com: What is the background for this study?
Response: It’s been known for many years that chronic tobacco smokers have poor endothelial function, even if they have not smoked recently, and so do non-smokers who are frequently exposed to secondhand smoke. Endothelial dysfunction, even in otherwise outwardly healthy people, is an indication of unhealthy arteries and increased risk of cardiovascular disease later in life. I realized that many people who would presumably avoid secondhand smoke did not mind it if it came from cannabis, and I wondered if that could be true since both kinds of smoke included the thousands of chemicals that resulted from burning plant material.
A number of years ago, we developed a way to study changes in endothelial function in rats, using a technique very similar to how we measure it in humans, and we saw that, as in humans, even brief exposures to secondhand smoke from tobacco impaired vascular function in the rats. We subsequently showed that brief exposures to secondhand smoke from marijuana, and active smoking of marijuana, similarly impaired vascular function in the rats, even if the smoke was from marijuana lacking THC and the other cannabinoids. That again raised the question of whether the endothelial dysfunction observed in human tobacco smokers would also occur in human marijuana smokers, and whether secondhand smoke from marijuana should be avoided like secondhand smoke from tobacco.
These questions form the basis of our current study.. In our study, it is quite clear that chronic cannabis smokers had endothelial dysfunction similar to that of chronic tobacco smokers. Whether frequent exposure to secondhand marijuana smoke similarly impairs endothelial function like secondhand tobacco smoke is still unknown, and that’s one of the major questions we want to answer next.
MedicalResearch.com: What are the main findings?
1) The marijuana smokers had poor vascular function similar to that of tobacco smokers. The amount by which vascular function was lower in marijuana smokers than non-smokers was very similar to the amount by which it went down in tobacco smokers in our previous studies. In other words, the blood vessels don’t seem to care whether the smoke is from tobacco or cannabis to respond in this way.
2) Users of THC edibles also had poor vascular function, but apparently for different reasons. We say this because commercially available endothelial cells in a dish exposed to blood serum from the marijuana smokers exhibited reduced production of nitric oxide, which is a crucial molecule for vascular function, relative to effects of serum from non-users; but serum from THC users did not prevent nitric oxide production.
MedicalResearch.com: How is the mechanism distinct from tobacco-induced mechanisms?
Response: We suspect that tobacco smokers and marijuana smokers are experiencing the same effects of smoke, probably through an increased oxidative state that reduces bioavailable nitric oxide. The vessels don’t care where the smoke is coming from. The mechanism of the THC edible effect, however, is presumably different because of what I wrote above, that nitric oxide production from endothelial cells was not affected by the THC users’ serum. It may be related to cannabinoid receptors on the endothelial cells but this is only speculation on my part.
MedicalResearch.com: What should readers take away from your report?
Response: The bottom line is that smoking marijuana does not appear to avoid the harmful vascular effects of smoking tobacco, and neither does frequent use of THC edibles.
MedicalResearch.com: What recommendations do you have for future research as a results of this study?
Response: I’m still very interested in whether secondhand smoke exposure from marijuana has similar vascular effects to those of secondhand smoke from tobacco. This is what we hope to find out in the next phase of our study.
MedicalResearch.com: Is there anything else you would like to add? Any disclosures?
Response: Neither I nor Dr. Mohammadi have relevant disclosures. As for anything else to add, I’ve been emphasizing a couple of points when I discuss our results:
First, we can only state what we have observed, which is that the cannabis users have poor vascular function, not that cannabis use causes poor vascular function. However, this suggests that cannabis use causes poor vascular function.
Second, the observations that marijuana smokers and THC users each have poor vascular function might make people conclude that the THC is responsible for all of this and the smoke is irrelevant. However, there are a number of reasons to make us think that the smoke itself is responsible regardless of anything the THC might be doing:
(1) tobacco smokers have the same functional problems and there’s no THC in tobacco smoke, (
2) in rat experiments that we have done previously, impairment of vascular (and cardiac) function from marijuana smoke also occured in rats exposed to smoke from marijuana that lacks all cannabinoids.
Citation:
Mohammadi L, Navabzadeh M, Jiménez-Téllez N, et al. Association of Endothelial Dysfunction With Chronic Marijuana Smoking and THC-Edible Use. JAMA Cardiol. Published online May 28, 2025. doi:10.1001/jamacardio.2025.1399
https://jamanetwork.com/journals/jamacardiology/article-abstract/2834540
More from Dr. Springer:
https://medicalresearch.com/secondhand-pot-smoke-just-bad-heart-tobacco/
—–
The information on MedicalResearch.com is provided for educational purposes only, and is in no way intended to diagnose, cure, or treat any medical or other condition. Some links may be sponsored. Products are not warranted or endorsed.
Always seek the advice of your physician or other qualified health and ask your doctor any questions you may have regarding a medical condition. In addition to all other limitations and disclaimers in this agreement, service provider and its third party providers disclaim any liability or loss in connection with the content provided on this website.
Last Updated on May 29, 2025 by Marie Benz MD FAAD
