What is the endocannabinoid system - and why does it matter?

What is the endocannabinoid system?

The endocannabinoid system (ECS) is a biological signalling system found throughout the human body - and everyone has it.

Its primary role is to help maintain homeostasis - the body’s internal balance - by regulating processes including mood, pain perception, sleep, appetite, metabolism, immune function, memory, and stress responses.¹²

Dr Stefan Broselid, Scientific Lead at The Medical Cannabis Clinicians Society, explains that while the endocannabinoid system is best known for its connection to cannabis, it is in fact one of the body's most important regulatory networks.

"For many people, the endocannabinoid system is known only through its connection to cannabis. Yet it evolved as a fundamental regulatory system in the human body long before scientists discovered that plant cannabinoids could interact with it," he says.

The ECS was only identified in the late 20th century when researchers were studying how THC (tetrahydrocannabinol) the main psychoactive compound in cannabis, affects the brain. ³

Here they discovered something unexpected: THC wasn’t acting randomly, it was binding to specific receptors already present in the body.

These receptors were part of a system designed to interact with the body’s own natural “cannabinoid-like” chemicals.

This led to the discovery of cannabinoid receptors and, eventually, the endocannabinoid system.

The ECS is built from three core components that work together as a communication network:⁴

1. Endocannabinoids

These are molecules the body produces on demand. The two best understood are:

• Anandamide - which is involved in mood, reward, and stress regulation.

• 2-AG (2-arachidonoylglycerol) - which is more abundant and plays a major role in immune and nervous system signalling.

Unlike hormones, endocannabinoids are not stored. Instead they are made when needed, used briefly, and then broken down.

2. Cannabinoid receptors

These are proteins found on the surface of cells. They receive signals from endocannabinoids and trigger a response inside the cell.

• CB1 receptors - found mostly in the brain and central nervous system and are involved in memory, coordination, appetite, mood, and pain processing.

• CB2 receptors - found more widely in immune tissues and are involved in inflammation and immune regulation.

3. Enzymes

Once endocannabinoids have delivered their message, enzymes break them down so the signal doesn’t continue indefinitely.

The two key enzymes are:

• FAAH - which breaks down anandamide.

• MAGL - which breaks down 2-AG.

This system helps keep signalling precise and tightly regulated.

The ECS does not control a single function. Instead, it acts as a balancing system that fine-tunes many processes across the body.⁴

Broselid explains: "It helps the body respond appropriately to internal and external changes, for example, adjusting how strongly you feel pain after injury, how hungry you feel after not eating, or how alert you are during stress."

Because of this, the ECS is involved in a wide range of functions, including:⁵

• Sleep and wake cycles.

• Appetite and energy balance.

• Stress response and emotional regulation.

• Pain sensitivity.

• Immune activity and inflammation.

• Learning and memory formation.

"A helpful way to think about it is that the ECS doesn’t “turn systems on or off”, instead, it helps dial them up or down depending on what the body needs at any given moment," adds Broselid.

Cannabis interacts with the ECS in two main ways: by directly activating cannabinoid receptors and by indirectly influencing how the system regulates and resets itself.⁴

THC and the ECS

THC is the main psychoactive compound in cannabis. It primarily binds to CB1 receptors, which are found in the brain and central nervous system.⁶

Because of this, THC can affect multiple brain functions at once including mood, perception, appetite, memory, coordination, and sensory experience.

THC activates the ECS more strongly and less precisely than natural endocannabinoids, which is why its effects feel intoxicating.

CBD and the ECS

CBD (cannabidiol) does not strongly bind to CB1 or CB2 receptors. Instead, it appears to influence the endocannabinoid system indirectly rather than directly activating cannabinoid receptors such as THC.

Researchers believe CBD may modulate receptor activity, influence the breakdown of endocannabinoids, and interact with other related signalling systems in the body.⁷

Unlike THC, CBD is not intoxicating and does not produce a “high.” Its effects are generally considered more subtle and complex, and scientists are still working to fully understand exactly how it functions within the ECS.

Broselid describes the ECS as a "rapid-response messaging system" that helps the body adapt to changing conditions.

"When the body experiences a change, such as stress, injury, or shifts in energy balance," he explains, "it produces endocannabinoids on demand."

These molecules travel to nearby cells and bind to cannabinoid receptors, triggering signals that help the body respond appropriately.⁸

Once their job is done, Broselid says, enzymes quickly break the endocannabinoids down so the signal does not continue longer than necessary.

In simple terms, the process follows a cycle of:

produce → signal → adjust → reset

While the ECS operates automatically, research suggests that several lifestyle factors may influence how actively it functions.

Exercise

Physical activity is one of the most well-established influences on endocannabinoid activity and is thought to play a role in the “runner’s high” feeling.⁹

Sleep

The ECS is involved in regulating sleep-wake cycles, and consistent, restorative sleep supports overall biological balance.¹⁰

Stress

Chronic stress affects many regulatory systems in the body, including the ECS. Managing stress may help support more stable signalling.¹¹

Diet

Certain dietary fats provide the building blocks used in endocannabinoid production, although the relationship between nutrition and ECS function is still being studied.¹²

It’s important to note that these factors don’t “boost” the ECS in a direct or guaranteed way, but they may support its normal functioning as part of overall physiological health.

“The endocannabinoid system is one of the body’s key regulatory networks,” says Broselid, highlighting its role in maintaining balance across multiple physiological systems.

Because it influences so many core processes, the ECS has become a major focus in neuroscience and medicine.

It also helps explain why compounds found in cannabis can have such wide-ranging effects, from altering perception and appetite to influencing pain and relaxation.

However, as Broselid notes, much about the ECS is still being uncovered. Scientists continue to investigate how it operates across different tissues and individuals, but it is now clear that the ECS plays a central role in maintaining balance throughout the body.