A new study reveals that healthy individuals who regularly smoke marijuana or consume THC-infused edibles exhibit early markers of cardiovascular disease similar to those observed in tobacco smokers. This research, led by Professor Matthew Springer from the University of California, San Francisco, is reportedly the first to investigate the effects of THC on vascular function in humans.
The study analyzed vascular function in three groups: regular marijuana smokers, regular users of THC edibles, and non-users. Results showed a 42% reduction in vascular function for marijuana smokers and a 56% decrease for those consuming THC edibles compared to non-users. However, the authors caution that these findings demonstrate an association rather than a direct causal link, meaning that while cannabis users exhibited poorer vascular function, it cannot be definitively stated that cannabis use caused this decline.
Dr. Andrew Freeman, a cardiovascular expert not involved in the study, expressed surprise at the findings related to THC edibles, questioning whether these forms of cannabis might carry risks previously underestimated. He emphasized the need for larger studies to draw more conclusive results.
Endothelial cells, which line blood vessels, are crucial for regulating blood flow by releasing nitric oxide. When these cells become inflamed, they can lead to plaque accumulation in arteries, raising the risks of heart attacks and strokes over time. The study did not measure plaque levels, but Springer noted that unhealthy blood vessels struggle to dilate properly, which could predict future cardiovascular issues.
Prior research has established correlations between marijuana use and cardiovascular conditions. A February 2024 study indicated that daily cannabis users face a 42% increased risk of stroke and a 25% higher risk of heart attack compared to non-users. Regular marijuana consumption can elevate the risk of coronary artery disease by one-third, as highlighted in a February 2023 study.
The American Heart Association has advised against smoking or vaping any substances, including cannabis, due to potential harm to heart and lung health. Their 2020 guidance indicated that heart rhythm irregularities, such as tachycardia and atrial fibrillation, can occur shortly after smoking THC-containing cannabis.
In the study involving 55 participants aged 18 to 50, none were tobacco smokers or vapers. Researchers used ultrasound technology to assess the dilation of the upper arm artery after temporarily restricting blood flow with a tight cuff. The extent of endothelial cell damage was associated with the frequency and amount of cannabis use.
Participants who reported higher cannabis use experienced more significant vascular function impairment. Mohammadi, the lead researcher, stated that increased cannabis consumption—whether smoked or ingested—correlates with poorer vascular performance. Additional tests on the neck and thigh indicated that cannabis users did not show increased stiffness in blood vessel walls compared to non-users.
A laboratory analysis involved incubating endothelial cells with blood serum from cannabis smokers and edible users. The results showed that cells from edible users maintained nitric oxide production, while those exposed to serum from marijuana smokers produced 27% less nitric oxide. This finding aligns with previous studies on tobacco, where smokers also showed a significant decrease in nitric oxide production.
Springer warns against attributing the vascular damage solely to THC; the smoke itself may also contribute. Research involving rats exposed to marijuana smoke without cannabinoids indicated vascular and cardiac issues, suggesting that switching from tobacco to marijuana does not mitigate cardiovascular risks. He emphasized that smoking marijuana subjects users to both the harmful effects of smoke and THC.
Freeman noted the complexity of cannabis consumption, suggesting there could be an optimal level of use for health benefits. Further research is necessary to identify any potential thresholds for safe consumption.
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