Long-Term Marijuana Use Doesn’t Harm Physical Health, Except For Your Gums

Marijuana use doesn't seem to have a big impact on one's physical health even after years of heavy use, study says.

It has, however, one negative health effect, and that is on the teeth.

The study, which was published in JAMA Psychiatry, analyzed data from 1,037 participants from New Zealand. The researchers followed the participants from birth until the age of 38, and looked at whether marijuana use from age 18 to 38 had an impact on indicators of physical health, such as lung function, glucose control, blood pressure, systemic inflammation, waist circumference, HDL cholesterol, triglycerides and body mass index (BMI).

Researchers discovered that those who used marijuana over the last 20 years only reported teeth problems.

At age 38, those who smoked pot had worse periodontal health that those who did not, and no other health problems seemed to surface.

"We don't want people to think, 'Hey, marijuana can't hurt me,' because other studies on this same sample of New Zealanders have shown that marijuana use is associated with increased risk of psychotic illness, IQ decline and downward socioeconomic mobility," Madeline Meier, lead author of the study and assistant professor of psychology at Arizona State University, said in a report published in ZME Science.

However, tobacco use was linked to many physical health problems, such as worse lung function, more inflammation and poor metabolic health.

According to the researchers, the study cannot prove whether marijuana causes gum or periodontal disease. But physicians could still warn their patients that cannabis use may "put them at risk for tooth loss."

The study, however, did not explain why pot was linked to poor dental health. "Our analyses show that this association was not explained by tobacco smoking, alcohol abuse or less tooth brushing and flossing," Meier said.

The researchers also found that marijuana use over time was linked to lower BMI, smaller waist circumference and better HDL cholesterol, which suggests that cannabis may have an effect on a person's metabolism.

"There are definitely health risks associated with heavy marijuana use, but there just aren't as many as we previously thought," Dr. Kevin Hill, marijuana addiction expert and assistant professor of psychiatry at Harvard Medical School, said in a statement published in Time.

"The answers with marijuana aren't exactly what we would have expected them to be, and this is a great example. You need to be willing to change your mind on these issues," Hill added.