#81 – Debra Kimless, M.D. & Steve Goldner, J.D.: Cannabis – the latest science on CBD & THC

KEYPOINTS

• 01

  Both guests have a commercial stake, and Attia flags it up front

  Goldner is founder and CEO of Pure Green, and Kimless, an anesthesiologist, is its chief medical officer. Attia tells listeners to take everything with a grain of salt, while saying that after hours on and off mic he believes their intentions go beyond business. He expects the field to change enough that he'll need to revisit it within a year.

• 02

  THC and CBD act on the endocannabinoid system in different ways

  THC binds the CB1 receptors that produce intoxication. According to the guests, CBD doesn't sit directly on CB1 or CB2. Instead it works indirectly, for example by slowing the breakdown of the body's own endocannabinoids, or through other receptors altogether. In the raw plant both exist as acid forms and only become active after time and heat remove the carboxyl group, which is why eating raw cannabis won't get you high.

• 03

  'Hemp' is a legal category, not a separate plant

  Under US law, hemp is cannabis with less than 0.3% THC. Growers crossbreed cannabis to stay under that line, so modern hemp is very different from the industrial hemp of the Constitution era. Hemp-derived CBD now shows up in lotions, teas, ice cream and vape cartridges, many sold through a large gray or black market.

• 04

  Cannabis is a botanical mixture, not a single molecule

  Kimless cites more than 100 cannabinoids, more than 80 terpenes, plus flavonoids and other compounds that may act together. Their argument is that formulations combining ingredients can work at lower doses than a purified isolate. Attia frames this as the opposite of the reductionist, one-drug-one-target view he was trained in.

• 05

  THC's risks are mostly individual and depend on dose

  Some people feel calm on a small dose. Others get panic, anxiety, a racing heart or a spike in blood pressure, sometimes even at low doses. Kimless agrees high-dose THC can worsen schizophrenia, but argues CBD with little or no THC may still help such patients. On teenagers, she says she wouldn't advocate any chemical substance for a developing brain unless it's medically needed, such as for a seizure disorder.

• 06

  Acute lethality is extraordinarily low

  The guests cite a DEA attorney, writing in support of descheduling, who estimated that a 75-kilogram man would have to smoke about 1,500 pounds of cannabis flower in 15 minutes to die, and that the cause would probably be carbon monoxide, not cannabis itself. That says nothing about chronic, psychiatric or developmental risks, which the episode treats separately.

• 07

  The guests argue cannabis is not a gateway drug

  Kimless says NIDA no longer calls cannabis a gateway and that Colorado didn't see increased youth use after legalization. She also cites lower opioid prescribing in states with dispensary access and trials using CBD to help people come off methadone or heroin, which is why she calls it a possible 'exit drug'. These are the guests' readings of the evidence; Attia notes he doesn't know that literature himself.

• 08

  Vaping risks include additives never tested for inhalation

  Thinning agents such as propylene glycol and vitamin E acetate are 'generally recognized as safe' (GRAS) for eating, not for heating and inhaling. Heating propylene glycol can create formaldehyde. Goldner explains that the FDA's GRAS status covers specific uses, and that many cannabis products weren't tested for safety before they shipped.

• 09

  Edibles are unpredictable

  Swallowed cannabis goes through first-pass metabolism in the liver. Kimless puts onset at 60–90 minutes, with only about 8% bioavailability in the best case, and effects lasting 8–10 hours. A full or empty stomach and time of day change absorption, so even an accurately labeled edible won't give a repeatable dose. That's why people stack doses and get far more intoxicated than they meant to.

• 10

  THC tolerance is real but may plateau

  Heavy use down-regulates receptors, which Kimless says reset after a couple of days off. She contrasts it with opioids, where tolerance escalates and can flip into increased pain sensitivity. She cites Dutch medical-program data in which the average patient stabilized at about 750 milligrams of cannabis a day rather than continuing to increase.