Biohacker and tech entrepreneur Bryan Johnson, known for spending millions to slow down ageing, is back with another longevity PSA — this time about weed. In a new Instagram reel that has already racked up almost 8 lakh views, the 47-year-old warns about the effect of cannabis on cardiovascular health. Citing a recent study, Johnson says that both smoking and eating cannabis significantly reduce blood flow, just like tobacco.He said, “Kids, here’s the blunt truth about weed. A new study just came out, and here’s what it found. Smoking or eating cannabis harms your arteries equal to tabacco. Blood flow dropped 40% for smokers, 50% for edibles. This is based on a marker called flow-mediated dilation (FMD). It measures how well your blood vessels expand.”He added, “This is not an anti-weed rant. This is a pro-blood flow PSA. Just like tobacco, cannabis may come at the cost of a healthy heart. So, whether it’s in a pipe or a brownie, weed does not vibe with your longevity,” he said in the video. Johnson’s warning sparked a flurry of reactions online. “Na bro it helps me fight my demons,” wrote one user. Another quipped, “Switching to meth.” Another person revealed, “I don’t like weed anymore. It makes me feel like crap and gives me anxiety (sic).”One user reflected on their heavy use of weed, stating, “I grew up smoking pot regularly at a very young age. It’s addicting, and makes you stupefied and unmotivated. Lighting anything on fire and breathing it in can’t be good for you.”So, how reliable is flow-mediated dilation (FMD) as a marker for assessing the long-term cardiovascular risks of cannabis use?Dr CM Nagesh, general secretary at the Indian College of Cardiology, tells indianexpress.com, “Flow-mediated dilation is one of several tools researchers use to assess how blood vessels respond to stress and overall vascular health. It provides valuable insights into endothelial function, which plays a crucial role in cardiovascular health and well-being. While FMD changes can indicate early signs of blood vessel dysfunction, it is important to understand that it does not provide a complete picture of long-term risk, especially when it comes to substances like cannabis, which may affect individuals differently.” View this post on Instagram A post shared by Bryan Johnson (@bryanjohnson_) In research on cannabis use, he says, “FMD has shown some acute impacts, such as temporary narrowing of blood vessels. However, long-term studies are still in development, and many other variables, such as genetics, overall lifestyle, and frequency of use, need to be considered. FMD can be one piece of the puzzle, but it is not a standalone measure for determining long-term cardiovascular outcomes related to cannabis.”Story continues below this adSmoking vs. edibles: The difference in impact Dr Nagesh mentions, “Yes, the method of cannabis consumption can influence its effects on cardiovascular and respiratory systems. Smoking cannabis introduces combustion-related toxins into the body, which may irritate the lungs and potentially impact heart function, especially when used regularly. This form of consumption also delivers cannabinoids rapidly, which can lead to sudden changes in heart rate and blood pressure in some users.”On the other hand, he notes that edibles have a different effect on the body. They are processed through the digestive system and may result in a slower onset of effects, but a longer duration of action. While they avoid the risks associated with inhalation, they are not entirely without concern. The potency and delayed effect can sometimes lead to overconsumption, and the impact on cardiovascular health through this route remains to be studied. How even moderate cannabis use negatively impacts long-term healthDr Nagesh stresses that health is “a balance between physical well-being, emotional regulation, and overall life satisfaction.” Moderate cannabis use, in specific individuals, may not pose serious health risks, particularly if it does not interfere with daily functioning or emotional stability. “However, long-term use — especially starting at an early age or used frequently — can be associated with changes in memory, attention, and motivation in some users,” he says. The key lies in moderation, individual awareness, and understanding the role substances play in one’s overall life and health. Ultimately, mental well-being and physical longevity should be seen as interconnected rather than opposing goals. Finding a lifestyle that supports both can vary from person to person.Story continues below this adDISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.