People who consume cannabis more than once a month have an increased risk of heart disease and heart attack, according to a new research, but the same study has also identified a mechanism and a substance that might reduce the risk.
While links between weed and poor heart health have already been identified, recent research sheds light on the relationship''s limitations, as well as analyzing data from a huge sample.
The study found that tetrahydrocannabinol (THC), the plant''s psychoactive component, can lead to both inflammation in the endothelial cells that line the insides of blood vessels, as well as atherosclerosis.
According to a Stanford university biologist, the bacterial strain is significant on the cardiovascular system. "As more states legalize marijuana use, I anticipate we will begin to see a spike in heart attacks and strokes in the next years."
"Our experiments of human cells and mice demonstrate how THC exposure induces a harmful molecular cascade in the blood vessels. It''s not a benign medication," says the author.
A human part of the study involved records of 500,000 participants in the UK Biobank project. Around 11,000 of those individuals smoked cannabis more than once a month, and they were significantly more likely to experience a heart attack.
Cannabis users were more likely than non-cannabis users to have their first heart attack before the age of 50. These early heart attacks can further increase the possibility of future heart attacks and other cardiovascular difficulties.
Although it isn''t enough to demonstrate direct causation, the study was focused on other factors, such as age, body mass index, and sexual orientation. It''s enough to establish marijuana use as a risk factor for cardiovascular disease.
Researchers discovered that the number of inflammatory molecules in volunteers'' blood increased significantly in the three hours after using a cannabis cigarette. That inflammation can lead to heart attacks.
THC is promoting inflammation in human endothelial cells grown in the lab, and lab mice would develop significantly larger atherosclerosis plaques if they were injected with THC. It all adds up to a pretty broad association.
THC helps to bind to a receptor called CB1 in the human brain. The researchers continued to develop machine learning techniques to identify CB1 antagonists, molecules that might limit this binding when the receptor becomes overactive.
They were successful in their search by identifying genistein, a naturally occurring protein in soybean that, in mice, seems to minimize the harmful effects of THC (inflammation and atherosclerosis) while keeping the ones that are beneficial for medical use (including diminishing pain and stimulating appetite).
In the past, side effects in patients such as increased anxiety and mood problems have hindered scientists from using CB1 antagonists, but the early signs are that these problems might not be discovered with genistein.
"We''d''ve seen no clear reduction of the usual painkilling or sedating effects of THC in mice that contribute to marijuana''s potentially beneficial medicinal properties," said Chandy.
"So genistein is potentially a safer drug than previous CB1 antagonists. It is already used as a nutritional supplement, and 99 percent of it stays outside the brain, thus it shouldn''t cause these particular side effects."
The next step is to conduct human clinical trials to see if genistein can reduce the risk of heart disease in weed smokers. CBD (cannabidiol) is one of the cannabis compounds that does not have the psychoactive effects of THC.
THC is still a controlled substance in the United States, indicating that it is strictly regulated for medical research use. Despite that, the researchers remain skeptical about the long-term health consequences of regular weed smoking.
The cannabis market continues to grow in the United States, and the researchers argue that it may be decades before the effects of this on cardiovascular health will be observed. In the meantime, further research will be invaluable.
"Genistein works quite well to mitigate the damage of the endothelial vessels caused by marijuana without limiting the effects marijuana on the central nervous system, and it may be a way for medical marijuana users to protect themselves from a cardiovascular standpoint," said radiologist Joseph Wu of Stanford University.
Cell has published the research.