Marijuana Users Issued Warning by New Study

Newsweek

6 days ago

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New research finds that regular marijuana use, including both smoking and THC-laced edibles, is linked to early warning signs of cardiovascular disease.
Why It Matters
The growing legalization and widespread use of marijuana in the United States has sparked concerns about short- and long-term potential health impacts. New studies such as this indicate a measurable risk of cardiovascular problems for young and otherwise healthy marijuana users, suggesting that marijuana use could have dubious health outcomes.
What To Know
The study, led by Leila Mohammadi at the University of California, San Francisco (UCSF) and published in the peer-reviewed medical journal JAMA, examined the potential connection between THC smoking and ingestion, and endothelial dysfunction—where the inner lining of blood vessels, the endothelium, is unable to function properly and could lead to an array of cardiovascular problems, per The Cleveland Clinic.
This cross-sectional study of 55 participants discovered that vascular endothelial function was impaired in both chronic marijuana smokers and tetrahydrocannabinol (THC) edible users, whereas serum from marijuana smokers but not THC-edible users blunted nitric oxide production in cultured endothelial cells.
Employees inspect cannabis plants at cannabis grower Hollandse Hoogtes, where regulated cannabis cultivation takes place in a grow center, in Bemmel, Netherlands, on April 1, 2025.
Employees inspect cannabis plants at cannabis grower Hollandse Hoogtes, where regulated cannabis cultivation takes place in a grow center, in Bemmel, Netherlands, on April 1, 2025.
SEM VAN DER WAL/ANP/AFP via Getty Images
These studies highlighted impaired blood vessel function and a higher likelihood of heart attacks among marijuana users, echoing risks previously associated with tobacco smoking but "via different mechanisms."
Such findings could challenge previous assumptions that marijuana is a benign alternative to tobacco.
Early Cardiovascular Signs Detected
The study divided the participants into three groups: marijuana smokers, THC-edible users, and nonusers. Researchers observed that marijuana smokers showed a 42 percent reduction in vascular function, while THC-edible users experienced a 56 percent reduction compared to those who did not use marijuana.
Comparable to Tobacco in Vascular Impact
Endothelial cells, which line blood vessels and regulate blood flow, were found to release significantly less nitric oxide—a chemical vital for dilation—in marijuana and THC-edible users.
Heart Attack, Stroke and Death Risks
A retrospective analysis of over 4.6 million people under age 50, published in March in JACC Advances, revealed that marijuana users faced a more than sixfold increased risk of heart attack, a fourfold risk of ischemic stroke, and a threefold risk of cardiovascular death, heart attack, or stroke, compared to non-users.
Meta-Analysis Confirms Higher Heart Attack Risk
A meta-analysis presented to the American College of Cardiology pooled data from 12 studies involving 75 million people. The association between marijuana use and heart attack was positive, with current users being 1.5 times more likely to suffer a heart attack than nonusers, according to SciTechDaily.
Associations, Not Direct Causes
Scientists cautioned that these findings show strong associations but do not definitively prove marijuana or THC causes vascular damage or heart attacks.
Dr. Springer said, "We can only state that the cannabis users have poor vascular function, not that cannabis use causes poor vascular function."
Confounding factors like concurrent use of other drugs were not ruled out in these studies.
Based on these results, researchers urged clinicians to ask patients about marijuana use during cardiovascular risk assessments. Dr. Ibrahim Kamel, lead author of the retrospective study, said, "At a policy level, a fair warning should be made so that the people who are consuming cannabis know that there are risks," according to SciTechDaily on March 18.
What People Are Saying
Matthew Springer, professor of medicine at the University of California, San Francisco, and one of the co-authors, told CNN: "We're looking at a window in the future, showing the early changes that may explain why smoking marijuana has been linked to later heart disease."
Dr. Ibrahim Kamel, clinical instructor at Boston University and internal medicine resident at St. Elizabeth Medical Center, told SciTechDaily in March: "Asking about cannabis use should be part of clinicians' workup to understand patients' overall cardiovascular risk, similar to asking about smoking cigarettes...a fair warning should be made so that the people who are consuming cannabis know that there are risks."
Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver, told CNN: "Could it be that other forms of marijuana — teas, tinctures, edibles — are perhaps not as benign as we once thought?"
What Happens Next
Researchers have called for larger, long-term studies to more conclusively determine the direct effects of marijuana and THC products on cardiovascular health and to identify safe usage levels, if any. Future policy guidance and clinical recommendations may be updated in light of further research outcomes.