A new study from researchers at UC San Francisco has found that chronic cannabis use—whether smoked or eaten—can significantly impair heart and blood vessel health.
The study, published May 28 in JAMA Cardiology, revealed that regular cannabis users had blood vessel function similar to that of tobacco smokers, even if they were otherwise healthy and didn’t use nicotine.
Researchers discovered that people who used marijuana at least three times a week for over a year showed about a 50% reduction in vascular function compared to people who didn’t use cannabis. Poor vascular function increases the risk of serious conditions such as heart attacks, high blood pressure (hypertension), and stroke.
The study involved 55 participants between October 2021 and August 2024. All participants were regular cannabis users but did not use nicotine in any form.
Among them, cannabis smokers had used marijuana for an average of 10 years, while those who consumed edibles had done so for about five years. Despite differences in how they consumed cannabis, both groups experienced similar levels of reduced blood vessel function.
However, researchers found some important differences between smoking and eating cannabis.
Blood tests revealed that marijuana smokers had harmful changes in their blood serum—the fluid part of the blood—suggesting damage to endothelial cells, which line the inside of all blood and lymph vessels and are crucial for healthy circulation. This damage was not observed in people who consumed cannabis in edible form.
Endothelial damage is a known risk factor for cardiovascular disease because these cells help control blood pressure, prevent clotting, and keep blood vessels flexible. When these cells are injured, the risk of clots, inflammation, and narrowed arteries rises.
Interestingly, although both smoking and ingesting cannabis reduced vascular function, the cause behind the damage appears to differ. The fact that only smokers showed changes in blood serum suggests that smoking introduces harmful substances that directly impact the bloodstream and blood vessels.
But even without these serum changes, THC (the main psychoactive compound in cannabis) still seems to impair vascular health when consumed in edible form—though the exact mechanism remains unclear.
According to first author Dr. Leila Mohammadi and senior author Dr. Matthew L. Springer, these findings raise concerns about the long-term heart and vascular health of people who use cannabis regularly, especially as marijuana becomes more widely used and legalized around the world.
In summary, this study provides clear evidence that chronic marijuana use—whether smoked or eaten—can harm cardiovascular function, with additional risks for smokers due to possible chemical damage to blood vessel lining.
As the researchers continue to explore how THC affects the cardiovascular system, the public and healthcare providers may need to consider these risks when making decisions about cannabis use.
If you care about heart disease, please read studies that herbal supplements could harm your heart rhythm, and how eating eggs can help reduce heart disease risk.
For more health information, please see recent studies that apple juice could benefit your heart health, and results showing yogurt may help lower the death risks in heart disease.
The study is published in JAMA Cardiology.
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