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CBD Bioavailability: What Is It And Why It Matters?


CBD bioavailability is an important, yet often overlooked aspect of CBD products. The bioavailability of CBD is affected by the way you consume it: transdermal, rectal, oral, sublingual, and inhalation.

CBD Bioavailability: The Highlights

  • The quantity of the CBD product and milligrams provided are not as significant as the quality and form that ensure the consumer receives the maximum benefit from their CBD.
  • CBD bioavailability is affected by the first-pass metabolism phenomenon in the liver.
  • It’s important to understand the bioavailability of CBD to ensure you receive the maximum benefits from the product you use.
  • CBD bioavailability is not a priority for some manufacturers, even though quality should be considered over quantity.
  • Several health benefits are influenced by the bioavailability of CBD.

What Is Bioavailability?

Bioavailability is a word that is often used in the medical and pharmaceutical world, but its true meaning tends to be confusing or misunderstood. The actual process is more simple than you might think.

To put it simply, bioavailability is the ability for a substance to be absorbed and used by the body. Not all CBD products are created equal in this regard.

While it can be explained easily, bioavailability is actually a complex process. It can be best described by using the acronym, LADME. This represents the stages a substance goes through to be absorbed and used. LADME stands for:

  • liberation
  • absorption
  • distribution
  • metabolism
  • elimination

Liberation refers to the substance being broken down into its individual components by stomach acid and enzymes. Absorption takes place in the small intestine where the substance is taken into the blood and distributed as needed.

The final stages — metabolism and elimination — primarily take place in the liver and large intestine.

Why Does Bioavailability Matter?

This process, while complex, is important for many reasons. Primarily, and most obvious, the consumer of a substance whether a vitamin, food, or drug, wants it to be absorbed and used effectively.

No one takes a medication without being concerned with getting the maximum effects. Therefore, when a product is made the bioavailability should be one of the primary focuses.

This focus on bioavailability is not always the case with products that are made with less attention to quality and with a focus on cutting costs for the manufacturer. The rate at which a product is bioavailable can be impacted by other variables as well.

The consumers’ age, sex, gastrointestinal health, organ functions, metabolism, and genetics can all play a role in how well the substance is used by the body. The bioavailability of some products is decreased if taken with certain types of food or nutrients while others are increased.

The phenomenon of first-pass metabolism can also impact CBD absorption into the blood. This is when the dose of a drug or product is significantly decreased prior to being absorbed and is in turn excreted without ever being broken down and absorbed.

What Is The Best Way To Consume CBD?

CBD structural formula

Cannabidiol (CBD) can be consumed through a wide variety of methods. Each of these methods will carry with it a different level of CBD bioavailability. The exact bioavailability may be vastly different or minimally noticeable between each method.

But understanding the best way to consume CBD for the individual is important.

Vaping CBD has a different bioavailability than when it is ingested orally. An oral capsule may have better effects than a rectal capsule. Oral bioavailability can be more or less bioavailable than when CBD is taken through intravenous administration.

When a CBD product states it has a specific amount of CBD content, such as 20 percent CBD, the body may or may not take in that exact amount. How bioavailable the cannabis product is will impact that heavily.

A high-quality CBD that has high bioavailability will require less consumption from the individual taking the product to receive the same, if not better, effects as someone taking a lower quality but larger amount.

With the growth of the cannabis industry, especially in the realm of cannabis oil, consumers are becoming more concerned with the quality and effects of the cannabis products they are purchasing.

This has caused manufacturers to pay closer attention and give greater care to the way in which their cannabis plants are grown and how the products are manufactured.

Bioavailability Of Cannabis Joints

Marijuana has traditionally been consumed through simply smoking the plant. So the question has to be asked, how bioavailable is marijuana when smoked?

A 2005 study by Pain Research Management found that THC had a 30 percent bioavailability and that within 10 minutes peak blood levels within the plasma were reached. Essentially, it only took participants 10 minutes to get high.

THC and CBD are both important factors when smoking marijuana, but THC is most likely the priority for consumers as this is the element that gives the psychoactive effect. For those wanting to get the benefits of CBD over the psychoactive effect of THC, smoking hemp plants can be an option.

This is because hemp is low THC and high CBD. Inhalation is the fasted way the body absorbs CBD. A 1980 clinical trial by Clinical Pharmacology Therapy observed this when participants in the study reported feeling the effects of THC faster when inhaled.

Sublingual Tinctures Bioavailability

CBD Oil products

The sublingual gland under the tongue allows substances, such as sublingual drops, to be absorbed directly into the bloodstream rather than having to make its way to the small intestine.

This method of consumption is quicker than other oral options such as edibles and maintains its bioavailability better due to bypassing the harsh stomach acids. Sublingual products may also bypass the liver’s first-pass metabolism effect.

Consuming CBD through sublingual tinctures has its benefits. They often taste great and have beneficial effects.

However, the bioavailability may be impacted as they are often not water soluble, because oil and water do not mix, making it hard for it to be mix with the saliva in the mouth and be absorbed.

However, absorption rates ranging from 12 to 15 percent have been reported.

Oromucosal spray is a sublingual method to take in CBD through an oral route. Many patients with multiple sclerosis use THC: CBD Oromucosal sprays to help them manage their pain and perform daily functions and interactions.

Bioavailability Of Edibles

Because more body systems are involved in the LADME process of a product when it comes to edibles, they are often less bioavailable than other forms of hemp oil.

In fact, a 1986 study published by Biomedical & Environmental Mass Spectrometry reported the bioavailability rate of edibles at 6 percent while other numbers have been 4 to 20 percent, which is quite low.

Even if 20 percent were the best case scenario this would mean that only 20mg of a 100mg edible would be used by the body. However, a 10mg dose of THC is still a respectable amount to receive. This low bioavailability of edibles can be blamed, once more, on the first-pass effect of the liver.

It is also due to the harsh acids and enzymes the product has to come into contact with before reaching the small intestine. Once it reaches it, it will be absorbed into the bloodstream where it can be used by the body for beneficial effects.

The blood must first receive the CBD before it can react with the CBD receptors.

Bioavailability Of Topicals

The bioavailability of transdermal delivery can be quite misleading. When cannabidiol oil is applied topically it never actually reaches the bloodstream. The benefits seen with this method are due primarily to the body’s nearby cannabinoid receptors which are able to take in the beneficial CBD directly.

Because CBD is hydrophobic, doesn’t like water, it can be difficult for the body to absorb the product this way as well. Because of this, fatty acids like those from coconut oil can help in delivering CBD to the site of pain or discomfort.

A 2016 study by the European Journal of Pain by Hammell, showed pain from arthritis inflammation was reduced from topical use of CBD on rats.

Vaping Bioavailability

CBD vape pens and cbd cartridges

While oral consumption is great, inhaling has proven to be quicker and have longer lasting effects. Vaping CBD oil allows the cannabidiol to reach CBD receptors more quickly and allows for quicker effects from vaping CBD oil.

A 2016 study published in PLOS One by Lanz, showed the benefits of using the right CBD vape cartridges to increase the bioavailability of THC and CBD.

The bioavailability of CBD by inhalation through vaporizers has been reported up to 56 percent with a mean value of 31 percent. Inhalation produces great bioavailability because the lungs are highly permeable and have a large surface area for absorption.

Rectal Bioavailability

While it may not seem desirable, CBD can be taken in rectally through capsules or suppositories. This allows the product to reach the bloodstream quickly due to the vast amount of mucous membranes for direct absorption.

That pesky first-pass metabolism from the liver is decreased substantially due to the fact that of the three veins located in the anus only one is associated with the liver.

Why Bioavailability Matters

When it comes to CBD, bioavailability is not a secondary consideration, it is important to the consumer. This is especially true for those taking CBD for medicinal purposes such as pain relief, controlling Alzheimer’s disease symptoms, managing chronic pain, and living with anxiety.

These individuals want to ensure they are receiving the maximum amount of their CBD dose as possible. Bioavailability matters because it controls the effects of a substance and is the basis of why a product is being consumed.