Emerging scientific evidence indicates that conventional methods of marijuana consumption, including smoking and THC-infused edibles, are associated with early indicators of cardiovascular health issues.
Significance of Recent Findings
The increasing legalization and normalization of marijuana across the United States have raised alarms regarding its potential short- and long-term health consequences. Recent research underscores a tangible link between marijuana use and cardiovascular risks, even among young and otherwise healthy individuals. These findings challenge the perception of marijuana as a harmless substance and suggest that its health implications warrant serious consideration.
Key Insights from the Study
Led by Leila Mohammadi from the University of California, San Francisco (UCSF), and senior researcher Matthew Springer, the study was published in the peer-reviewed journal JAMA Cardiology. It explored the relationship between THC consumption-via smoking and edibles-and endothelial function, which pertains to the health of the inner lining of blood vessels. Impaired endothelial function is a precursor to various cardiovascular conditions, including hypertension and atherosclerosis, according to Cleveland Clinic experts.
Springer explained that the research was inspired by earlier findings showing that long-term tobacco smokers, even those who had recently quit, exhibited compromised endothelial health. Similarly, individuals exposed to secondhand smoke-whether from tobacco or marijuana-show signs of vascular dysfunction. This raised the question of whether marijuana smoke, which contains numerous chemicals from plant combustion, could have comparable adverse effects.
“Years ago, we developed a method to assess endothelial function in rats, mirroring techniques used in humans,” Springer shared with Newsweek. “We observed that brief exposure to secondhand tobacco smoke impaired vascular health in rats, and subsequent experiments revealed that even short-term exposure to secondhand marijuana smoke, as well as active smoking, caused similar vascular impairments-even when the marijuana lacked THC or other cannabinoids.”
The study, involving 55 participants, found that both chronic marijuana smokers and THC consumers exhibited significant reductions in endothelial function. Notably, serum from marijuana smokers who did not consume THC also hindered nitric oxide production in cultured endothelial cells, indicating vascular impairment.
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“Essentially, blood vessels respond similarly whether the smoke originates from tobacco or marijuana,” Springer emphasized. This challenges the common assumption that marijuana is a safer alternative to tobacco.
Early Warning Signs of Heart Disease
The research categorized participants into three groups: active marijuana smokers, edible THC consumers, and non-users. Results revealed that marijuana smokers experienced a 42% decline in vascular function, while edible THC users faced an even more pronounced 56% reduction compared to non-users. These findings suggest that both inhalation and ingestion of marijuana can negatively impact vascular health.
Increased Risks of Heart Attacks and Strokes
A comprehensive analysis involving over 4.6 million individuals under age 50, published in JACC Advances, demonstrated that marijuana users had more than a sixfold higher risk of experiencing a heart attack, a fourfold increased likelihood of ischemic stroke, and a tripling of the risk for cardiovascular death, compared to non-users.
Meta-Analysis Reinforces Heart Attack Concerns
A meta-analysis presented to the American College of Cardiology combined data from 12 studies encompassing approximately 75 million people. The analysis confirmed a significant association between marijuana use and increased heart attack risk, with current users being 1.5 times more likely to suffer a myocardial infarction than non-users, according to SciTechDaily.
Understanding Correlation Versus Causation
Experts caution that these studies establish strong associations but do not definitively prove that marijuana or THC directly cause vascular damage or heart attacks. Springer noted that while serum markers linked to endothelial dysfunction were observed in marijuana smokers, similar effects were not seen in edible THC consumers. This suggests that different mechanisms may be involved depending on the mode of consumption.
He added that the degree of vascular impairment correlated with the frequency of smoking sessions and the amount of THC ingested weekly. The research intentionally focused on individuals with relatively high usage levels to better understand potential risks.
“Our findings indicate that both smoking marijuana and consuming THC edibles can impair vascular health,” Springer concluded. “People should be aware that, at least at higher consumption levels, neither method should be considered entirely safe.” He also emphasized that public health policies should consider restricting marijuana smoking in areas where tobacco smoking is prohibited, to prevent involuntary exposure to harmful secondhand smoke.”
To ensure accuracy, the study controlled for confounding factors such as concurrent drug use through questionnaires and drug testing.
Based on these insights, clinicians are encouraged to inquire about marijuana use during cardiovascular risk assessments. Dr. Ibrahim Kamel, the study’s lead author, stated, “Public health messaging should include warnings about the potential risks of cannabis consumption, similar to those for tobacco.”
Expert Opinions and Future Directions
Matthew Springer remarked to Newsweek, “Our cumulative research in both animals and humans has at least dispelled the myth that marijuana is harmless. While the extent of its harm remains debated, it’s clear that cannabis and THC are not risk-free. They may offer some benefits, but these must be weighed against potential health dangers.”
Dr. Ibrahim Kamel, a clinical educator at Boston University, emphasized the importance of discussing cannabis use with patients, akin to smoking history, to better evaluate cardiovascular risk. He added, “Consumers should be informed that marijuana carries health risks.”
Dr. Andrew Freeman, head of cardiovascular prevention at Nationwide Jewish Health, questioned whether alternative forms like tinctures, teas, or edibles might be less safe than previously believed, prompting further investigation into their safety profiles.
Next Steps in Research and Policy
Researchers advocate for more extensive, long-term studies to clarify the impact of marijuana and THC products on cardiovascular health and to establish safe usage guidelines, if any. Future clinical recommendations and policies are likely to evolve as new evidence emerges.
Updated 5/29/25, 10:08 a.m. ET: This article now includes insights from Matthew Springer.
