Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

When some misinformed people hear of the grand opening of a new plant-based medical practice, one plant in particular may come to mind. Over the years, I’ve gotten a lot of questions about cannabis, and I figure it’s high time to try to clear the haze. I didn’t want to just take a pot shot, tokin’ effort, and end up with some half-baked puff piece. There are burning issues about a growing industry, with so much buzz and smoke and mirrors, the science can really take a hit. I mean, are there acute chronic effects? Blunt trauma from impaired driving, perhaps? I wanted to give the straight dope; weed out any doobieous research, and it’s been quite a trip. 420 articles published within just the past few months!

This is the review everyone was waiting for: “The [2017] Current State of Evidence” from the Institute of Medicine, “tasked with conducting a comprehensive review [on] the health effects of…cannabis.” Started out with 24,000 sources; whittled it down to about 10,000 to produce this 468-page document. What did they find?

I think it’s fair to summarize that they found the purported benefits to be much smaller and weaker than are often reported, but so too the purported risks. So, good news for the recreational user, who is mostly just worried about not getting cancer, but bad news for the patient who actually wants it to help their cancer. The only three benefits they could find “substantial evidence” for was as a treatment for “chronic pain in adults,” “chemo…-induced nausea and vomiting,” and relieving self-reported muscle tightness in patients with MS. Even archetypal medical marijuana indications, like glaucoma, failed to live up to expectations.

“Despite popular belief to the contrary, extensive research over decades has documented that marijuana is not effective in the management of clinical glaucoma,” a disease of increased pressure within the eyeball. I mean, it does lower pressure, but only for “about an hour.” And so, you’d have to smoke a dozen joints a day—and even if you did smoke those few thousand a year, your body gets used to it. And so, what little benefit there is disappears within a few months in most patients.

On the other hand, conspicuously missing from this list of adverse side effects of long-term or heavy use is any mention of chronic obstructive pulmonary diseases, like emphysema, which you can get from smoking tobacco. And similarly, it doesn’t look like smoking marijuana increases the risk of respiratory cancers, like lung cancer, or head and neck cancer—though cannabis may increase the risk of testicular cancer. There have been three studies so far on marijuana use and testicular cancer, appearing to increase risk about 50%—but only, it seems, for those smoking once a week or more, or for ten years or longer.

So, what did they conclude overall? Were they for legalization; opposed? Basically, they concluded, there simply isn’t enough research—”leaving patients, health care professionals, and policy makers without the evidence they need to make sound decisions” either way. Further: “This lack of evidence-based information…poses a public health risk.”

That’s one thing everyone on both sides can agree on: “the need for definitive clinical research.” Otherwise, we’re just left with “[a]necdotes,…blogs, and ad[s], which don’t “provide a sound basis for assessing the safety and efficacy of pharmacologic agents.” “Because cannabis is [just] a naturally occurring plant, and cannot be patented,” the pharmaceutical industry is MIA.

What we need are large clinical trials. Until then, we’re all just going to be “scratching our heads.” But, where’s the funding going to come from? For drug companies, interest in the plant is scant—where’s the payback?

Big Pharma is interested in “a reasoned approach,” however. “[T]he development of newer…cannabinoid modulators” in profitable pill form will, one day, writes this pharmacology professor, “make…the use of herbal cannabis a thing of the past.”

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