How does CBD and THC affect the human body?

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One of the great things about legalizing marijuana is that it freed up researchers to better understand how the plant—and it’s compounds CBD and THC—effects humans. Already the science is mind opening.

Since the 1970s scientists have known that the euphoric high comes from the plant’s interaction with the endocannabinoid system, an internal pathway operating throughout the body. Now they’re furthering their understanding of how the plant’s key compounds impart health benefits and the importance of something called the entourage effect.

Operating system

To understand how human and plant work together, a good place to start is with the endocannabinoid system. Part of the nervous system, it’s spread throughout the body, but concentrated in the brain. It plays a roll in things like mood, memory, motor skills, pain-sensation, and appetite.

Think of the endocannabinoid system as a pearl necklace. The neurons are the pearls and in the space between them is a receptor cell called CB1. When the body sends messages through the endocannabinoid system they travel as electrical impulses, passing from one neuron to the next through the CB1 “gates.” Each time a message passes between neurons a chemical called anandamide attaches to CB1, delaying the next impulse. The temporary shut off keeps messages from overstimulating the whole system.


Compounds in cannabis called cannabinoids (see the connection?) interact with the CB1 receptor. The two main ones are tetrahydrocannabinol, better known as THC, and cannabidiol, aka CBD. They share an identical chemical make up, but the atoms align in different shapes.

When you smoke or vape, the cannabinoids enter the blood stream through the lungs; when ingested, it’s through the digestive system. Either way, they ride around the body in the blood, interacting with the endocannabinoid system throughout the body, but mostly in the brain.

Leaving the gate open

THC and anandamide, the CB1 gate keeper, share nearly identical structures. So when THC comes across a CB1 receptor it slips into place just like anandamide. But instead of closing the gate, it locks it open, changing the body’s perception of pain, appetite, motor control, cognition, and creativity.

CBD’s structure doesn’t fit into the CB1 receptor, but it can block it, preventing THC from docking. That’s why the higher the percentage of CBD in cannabis, the less intense the high.

CB1 is only the most common gate keeper in the endocannabinoid system. Scientists think the shape of CBD matches other “gates,” including ones that control inflammation and anxiety.

Entourage effect

While each cannabinoid seems to have its own benefits, scientists have found they each work best in the presence of the other. CBD fights various forms of cancer better when it has trace amounts of THC. Same for treating cancer symptoms. A 2013 study found a THC and CBD spray worked better for pain management than just a THC spray. And, while using THC alone can be habit forming, patients using a THC and CBD combo didn’t ask to increase their dose.

Take away

Scientists continue to work on understanding the relationship between cannabis and the human body and CBD and THC. It’s early days yet. But it seems that for some reason the human body evolved to benefit from the plant.

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