Whether It’s Edibles Or Joints, Cannabis May Still Be As Bad For The Heart As Tobacco

SAN FRANCISCO — That joint might not be as harmless as you think. A new study reveals that chronic marijuana use — whether smoked or consumed as edibles — may impair blood vessel function in ways comparable to tobacco smoking.

Researchers at the University of California, San Francisco, found that chronic cannabis users show measurable signs of endothelial dysfunction, with significantly reduced blood vessel dilation. With states continuing to go down the legalization route, the findings, published in JAMA Cardiology, offer a serious warning to individuals turning to marijuana as a “safer” alternative to tobacco.

“There is a popular belief that marijuana smoke is harmless. However, marijuana smoke contains many of the thousands of chemicals contained in tobacco smoke,” the researchers write.

How Scientists Tested Cannabis Users’ Hearts

The study involved 55 healthy adults between ages 18 and 50 in the San Francisco Bay Area, divided into three matched groups: marijuana smokers (≥3 times weekly for ≥1 year), THC-edible users (≥3 times weekly for ≥1 year), and nonusers. All participants were confirmed non-tobacco users, and researchers screened for secondhand smoke exposure by testing for nicotine and cotinine in urine.

To assess vascular health, scientists measured each participant’s flow-mediated dilation (FMD), a standard method of gauging how well arteries expand in response to increased blood flow. They also tested pulse wave velocity (PWV), a measure of arterial stiffness, and ran lab experiments using participants’ blood serum on cultured human endothelial cells.

The Results Show Clear Differences

Marijuana smokers showed significantly reduced FMD (6.0%) compared to nonusers (10.4%). THC-edible users had even lower FMD (4.6%). Both differences were statistically significant. The reductions in FMD were similar to those reported in tobacco smokers in prior research.

Researchers also found a dose-response relationship: more frequent marijuana smoking and higher THC consumption were correlated with worse endothelial function.

In lab experiments, serum from marijuana smokers — but not edible users — reduced nitric oxide production in cultured endothelial cells. Nitric oxide helps arteries relax and maintain blood flow, so this decline suggests one mechanism by which smoking cannabis might impair cardiovascular function.

Different Methods, Same Heart Risk?

Both smoking and edible consumption of cannabis were associated with vascular dysfunction, though likely via different biological pathways. Smoke exposure appears to suppress nitric oxide directly, while THC edibles may affect the cardiovascular system through metabolic processes during digestion.

The study’s authors conclude that the vascular impairment in cannabis users was “similar to that observed in tobacco smokers, although apparently occurring via distinct mechanisms.”

What This Means For Cannabis Users

Cannabis use today continues to become more common across the U.S. While many view marijuana as safer than cigarettes or alcohol, this research adds to growing evidence that cannabis, especially when used chronically, may carry underappreciated cardiovascular risks.

The study is not without limitations. It was cross-sectional (not longitudinal), included only 55 participants, and couldn’t control for every variable related to strain, dose, or lifestyle. Still, the observed effects were strong enough to reach statistical significance.

The researchers conclude that chronic marijuana use, whether smoked or ingested, is associated with endothelial dysfunction, a known precursor to heart disease. As legalization expands, public health messaging may need to catch up with emerging evidence that marijuana use isn’t entirely benign.