It’s a well-established fact that marijuana use has few notable side effects and little in the way of genuine health risks. A new study finds that’s true even for people who smoke large amounts of pot over long periods of time.
Even tokers who consumed the drug for decades showed no signs it hurt their physical health, according to the study’s lead author, Madeline Meier of Arizona State University. The report appeared in June in JAMA Psychiatry, a publication of the Journal of the American Medical Association.
Researchers examined data on 1,037 New Zealanders who were tracked from birth to age 38. At several points between ages 18 and 38, scientists used lab tests and self-reports to measure the impact of regular cannabis use on each subject’s physical health.
Cannabis users had worse dental health
The results should be heartening, if surprising, to anyone who smokes pot. Marijuana, it turns out, leads to only one long-term health problem: bad teeth. By 38, subjects in the study had worse periodontal health than non-smokers. Otherwise, there were no negative long-term consequences for sparking up.
Compare that with tobacco, where long-term use provably inhibits lung function, increases systemic inflammation, and leads to poor metabolic health. Cigarettes are directly responsible for nearly half a million deaths a year in the United States alone. Marijuana has never killed anyone.
The study stopped at age 38, so it’s possible regular smokers could run into more serious health issues later in life. But there may be benefits to lifelong use that outweigh that risk. The researchers discovered cannabis use over long periods of time is linked to a healthier BMI, slimmer waistline, and better cholesterol levels.
Over-estimated risks of marijuana use
“There are definitely health risks associated with heavy marijuana use, but there just aren’t as many as we previously thought,” said Dr. Kevin Hill, an assistant professor of psychiatry at Harvard Medical School who wrote a commentary on the study in JAMA.
The researchers behind the new study used the same data set in 2012 to suggest heavy marijuana use has negative effects on the developing brains of teenagers. Those findings have been hotly disputed, both in academic circles and in the legal cannabis industry. The 2012 study found regular teen consumption that starts before age 18 is associated with an 8-point decline in IQ levels; other studies have since refuted that conclusion.
The scientists behind the new study said their findings offer more proof that the science of marijuana use is complicated – and unpredictable.
“The answers with marijuana aren’t exactly what we would have expected them to be, and this is a great example,” Hill said. “You need to be willing to change your mind on these issues.”
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