Marijuana may be legal in 18 states, Washington, D.C., and Guam, but that doesn’t mean frequent use is healthy. New research led by Stanford Medicine scientists found smoking pot more than once a month can increase the risk of cardiovascular disease and heart attack in middle age.
What’s more, THC (tetrahydrocannabinol), the component of the drug that gets you high, can cause inflammation in the cells that line blood vessels. It’s also blamed for atherosclerosis, or the buildup of fats in the artery walls of lab mice. The good news for people using marijuana to stimulate appetite, control nausea or dull pain: Researchers discovered genistein, a molecule that occurs naturally in soy and fava beans, can prevent the inflammation and atherosclerosis from occurring without taking away the feelings of being high.
“As more states legalize the recreational use of marijuana, users need to be aware that it could have cardiovascular side effects,” Joseph Wu, M.D., professor of cardiovascular medicine and radiology and director of the Stanford Cardiovascular Institute, says in a press release describing the research. “But genistein works quite well to mitigate marijuana-induced damage of the endothelial vessels without blocking the effects marijuana has on the central nervous system, and it could be a way for medical marijuana users to protect themselves from a cardiovascular standpoint.”
Frequent pot use can cause damage
To determine the impact marijuana has on the heart, researchers analyzed the medical and genetic data of about 500,000 people between the ages of 40 and 69 in the UK Biobank study. Of those people, close to 35,000 reported smoking cannabis, with 11,000 reporting they smoked pot more than once a month. Researchers controlled for age, gender and body mass, which can have an impact on the heart, and found that those who said they smoked more than once a month were more likely than others in the study to have a heart attack. What’s more, the frequent marijuana users were more likely than those who abstained to have their first heart attack before the age of 50, known in the medical community as a “premature heart attack.” Having one before 50 increases the chances of subsequent heart attacks, heart failure and life-threatening arrhythmias later in life.
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The culprit for all these heart troubles: THC, which binds to the cannabinoid receptor type 1 (CB1), a receptor on cells in the human brain, heart and vasculature system. The receptor recognizes naturally occurring cannabinoids that regulate mood, pain, metabolism and immune function. But when a person uses too much pot, it prompts inappropriate activation of CB1, leading to inflammation and atherosclerosis.
Genistein isn’t a mood killer
To test the effectiveness of genistein in countering that, researchers added the molecule to human endothelial cells treated with THC and gave it to THC-injected mice with high cholesterol. They found genistein blocked cannabis’s negative effects but not the psychoactive effects of THC on the brain. Researchers have not tested genistein on humans yet. They hope to conduct clinical trials to see if it can reduce cardiovascular diseases in pot smokers.
“There’s a growing public perception that marijuana is harmless or even beneficial,” Wu says. “Marijuana clearly has important medicinal uses, but recreational users should think carefully about excessive use.”
Donna Fuscaldo is a contributing writer and editor focusing on personal finance and health. She has spent over two decades writing and covering news for several national outlets, including The Wall Street Journal, Forbes, Investopedia and HerMoney.