Humans produce a range of chemical compounds called cannabinoids. They keep our bodies stable by binding to receptors on cell membranes and controlling the release of chemical messengers that regulate everything from how we experience pain to our moods.

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“Cannabinoids really seem to serve important functions in many different tissues throughout the body,” said Daniele Piomelli, a professor of neuroscience and pharmacology at UC Irvine.

While most people’s endocannabinoid systems naturally help maintain a state of homeostasis, or stability, conditions such as multiple sclerosis or treatments for diseases like cancer can throw off that balance. That’s when introducing cannabinoids made outside the body might help.

Marijuana also contains cannabinoids – at least 66 of them, Piomelli said. They’re not identical to the compounds our bodies produce. But some seem to act in much the same way, he said, helping to dull nerve pain, stimulate weak appetites, improve volatile moods and more.

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