What is it about about marijuana that makes you high? Most experienced users know that it is in fact THC (Δ9-THC or Tetrahydrocannabinol), but did you know that Cannabis in it’s basic plant form contains very little THC?
If you were to take a nice sized nug and swallow it whole (or chew it if you please), it really wouldn’t do much. This is due to the fact that rather than containing tetrahydrocannabinol, fresh Cannabis contains tetrahydrocannabinolic acid. Unfortunately, ingesting that isn’t going to do much.
When marijuana is heated, the carboxyl group is converted into water (H2O) and carbon dioxide (CO2). This occurs at 222.8°F (106°C). At this point the Cannabis can be eaten plain and will be fully absorbed by the body. When you smoke marijuana you are essentially rapidly decarboxylating the bud (and then just burning and inhaling all of the carbon in it as well). On a side note, many people advocate decarbing your herb before using it in baked goods. Apparently there’s more THC absorption, but I’m skeptical as to how much it really makes a difference.
Source: Science of Smoking: THC Decarboxylation | 420tainment