Welcome to the world of science. I didn't do well in high school science and have pretty much avoided addressing scientific subjects formally until now. That's because I've been delving into the science of marijuana to try to figure out some of the hows and whys of medical marijuana's workings. There are some 20,000 published scientific papers analyzing marijuana and its parts. So don't let anybody tell you there is too little known about marijuana to make a call regarding its usefulness.

Most of those papers are beyond my understanding, and making sense of those I could understand came with the help of a medical dictionary. But at least I'm trying. Most public policy and attitudes about the plant have been formed without the help of science. In fact, when President Richard Nixon ramped up the drug war in the early 1970s, it was in direct contradiction of the information and recommendations of his own marijuana task force.

There are probably lots of things we believe wthout a scientific basis, but maybe we're at a point where more clearheaded inquiry is possible. So here we go. First of all, delta-9-tetrahydrocannibinol, or THC as we commonly call it, is not the only active substance in marijuana. We know about it mostly because it's what gets you high. However it is not the only component that has medicinal value.

In my last column on medical marijuana, I posed questions about what in marijuana gives you the munchies, what relieves spasm and what causes memory loss — not to mention numerous other effects such as pain reduction and nausea relief. I can't give you definitive answers to all of that, but here is an explanation of how our bodies interact with marijuana.

The first thing we need to get a grip on is the cannabinoid system in the human body. OK, that word sounds like cannabis (the scientific name for marijuana), but that is only because the system was discovered during the 1990s during research on how marijuana affects the brain. Apparently, most multicellular organisms have a cannabinoid system and cannabinoid receptors that process the endocannabinoids (naturally occurring cannabinoids) that they produce. The system plays a role in regulating things like body temperature, blood pressure, hunger, etc.

Or as is formally stated by Neil Goodman, Ph.D., in "An Overview of the Endogenous Cannabinoid System," research suggests "that the endocannabinoids and their receptors constitute a widespread modulatory system that fine-tunes bodily responses to a number of stimuli."

"It's a regulatory system for things like appetite, circulation, pain response and immune response," says Paul Armentano, deputy director of the National Organization for the Reform of Marijuana Laws and expert witness on marijuana science. "Cannabinoids seem to regulate or maintain all of these different functions. ... When mice are bred not to have these receptors, a couple of very shocking studies show they die almost immediately. They suffer from failure to thrive and have no appetite at birth. If you force them to stay alive, they die of old age long before they become old. If this system doesn't work right, people don't survive."

A functioning cannabinoid system is essential for good health. Cannabinoids are found around injuries stabilizing nerve cells and promoting anti-inflammatory responses. There are cannabinoids in mothers' milk that give babies the munchies so that they learn how to eat.

Well, now, what are the cannabinoids and how do they affect specific maladies? The best-known is the aforementioned delta-9-tetrahydrocannibinol, aka THC. It is the main psychoactive ingredient in marijuana and produces the euphoria recreational users seek. It's also what gives you munchies. THC is very similar to the endocannabinoid (naturally occurring) that the body produces to tell you it's time to eat. Therefore when marijuana is eaten, THC binds to the cannabinoid receptors and, in addition to the euphoria, you feel like eating. There are further indications that it specifically stimulates taste buds related to sweets in the mouth.

Of up to 100 cannabinoids, a handful are known to show promise as therapeutic agents. The second most widely known cannabinoids is cannabidiol, or CBD, the most exciting cannabinoid for medical science. There are indications it's helpful for inflammation, nerve pain in disorders such as multiple sclerosis and Crohn's disease; it's an antispasmodic, anticancer, antidiabetic and neuroprotective substance.

"What makes marijuana so interesting is that we can explain why we get the results that we get," says Armentano. "We have this strain that is high in CBD. We know this person has Crohn's disease. We know that CBD interacts with receptors in the gastrointestinal tract and it reduces inflammation."

Most other known cannabinoids have a variety of healing properties that support those of THC and CBD. In fact, natural marijuana as a whole seems to work better than any of its isolated components. Cannabinoids as a group have a synergistic effect that produces better outcomes and fewer side effects. And those effects are both palliative (relieving symptoms) and curative (modifying the disease itself).

For instance, laboratory testing has indicated CBD slows down the proliferation of certain cancers, lowers the incidence of diabetes, and slows the development of multiple sclerosis. Also, some traditional drugs seem to work better when used in tandem with marijuana's cannabinoids and, over time, some patients have less need to take their traditional drugs.

Pharmaceutical companies have taken note of this and, mostly outside the United States, many drugs using marijuana are in the pipeline. In the United States, it is almost impossible for a pharmaceutical company to even experiment with drugs using any naturally occurring part of marijuana because it's listed as a Schedule 1 drug. There are synthetic cannabinoids such as dronabinol (marinol) and WIN 55,212-2 available in the United States. However, a British company, GW Pharmaceuticals, has developed an oral spray, Sativex, which employs natural parts of marijuana and treats MS. It is available in several other countries, including Canada.

> Email Larry Gabriel