Cannabidiol, commonly known as CBD, is a compound found in the cannabis plant. Unlike tetrahydrocannabinol (THC), CBD is not intoxicating and does not produce a “high.” While scientists are still working to fully understand its effects, CBD is marketed in many consumer products, including oils, lotions, and capsules.
How Cannabidiol Interacts with the Body
CBD primarily interacts with the body’s endocannabinoid system (ECS), a complex biological network that helps maintain internal balance. The ECS consists of three main components: endocannabinoids, cannabinoid receptors (CB1 and CB2), and enzymes. Endocannabinoids are naturally produced molecules in the body that act as messengers.
CB1 receptors are found throughout the central nervous system, including the brain, while CB2 receptors are located mainly in peripheral tissues and immune cells. CBD does not directly bind to these receptors in the same way THC does. Instead, it influences the ECS by modulating its activity, such as by inhibiting the enzyme fatty acid amide hydrolase (FAAH), which breaks down the endocannabinoid anandamide. This inhibition can lead to increased levels of anandamide in the body.
Beyond the ECS, CBD also interacts with other non-cannabinoid receptors. For instance, it can engage with transient receptor potential vanilloid 1 (TRPV1) receptors, which are involved in pain perception and inflammation. Additionally, CBD can influence serotonin receptors, which play a role in mood and anxiety regulation.
Understanding CBD Bioavailability
Bioavailability refers to the proportion of a substance that enters the bloodstream and is able to have an active effect. For CBD, the route of administration significantly impacts this proportion.
Oral ingestion, such as through edibles or capsules, generally has the lowest bioavailability, typically ranging from 6% to 20%. This is largely due to the “first-pass effect,” where CBD is metabolized by liver enzymes before it can enter the bloodstream. Consuming CBD with high-fat foods or in a lipid solution, such as MCT oil, can enhance its absorption and bioavailability by aiding its solubility.
Sublingual administration, where CBD oil is placed under the tongue, allows for direct absorption into the bloodstream through capillaries in the mouth, bypassing the initial liver metabolism. This method can result in a higher bioavailability, ranging from approximately 12% to 35%. Inhalation, via vaping or smoking, offers the fastest absorption and generally the highest bioavailability, often between 34% and 46%, because CBD quickly enters the bloodstream through the lungs. Topical application, like creams or patches, is primarily for localized effects and typically has minimal systemic absorption.
The Body’s Processing of Cannabidiol
Once CBD enters the bloodstream, it undergoes metabolism, primarily in the liver. The cytochrome P450 (CYP450) enzyme system is responsible for metabolizing most drugs and compounds, including CBD. Key enzymes involved in CBD metabolism include CYP2C9, CYP2C19, and CYP3A4. These enzymes convert CBD into various metabolites, such as 7-hydroxy-cannabidiol (7-OH-CBD) and 6-hydroxy-cannabidiol (6-OH-CBD).
CBD can also inhibit the activity of certain CYP450 enzymes. This inhibition can be significant because it may affect the metabolism of other medications taken concurrently, potentially leading to altered drug levels in the body. For example, CBD can inhibit CYP3A4 and CYP2C19, which could increase the plasma levels of drugs metabolized by these enzymes. After metabolism, CBD and its metabolites are typically eliminated from the body, mainly through urine and feces.
Biological Impacts of Cannabidiol
CBD has been studied for its anti-inflammatory properties, which may stem from its modulation of the endocannabinoid system and other pathways that regulate inflammatory responses. This can lead to a reduction in inflammatory markers.
CBD also exhibits anxiolytic, or anxiety-reducing, effects. This is thought to involve its interactions with serotonin receptors, which influence mood and stress responses. Additionally, CBD has shown neuroprotective qualities, helping protect nerve cells from damage. Research indicates it can reduce neuroinflammation, oxidative stress, and cell death in certain neurological models.
Furthermore, CBD is recognized for its analgesic, or pain-relieving, effects. This property is likely linked to its influence on various pain pathways, including those involving the endocannabinoid system and TRPV1 receptors.