Bioavailability – what you need to know…


No two CBD products are the same. Each has its value, but if we look at the sciencey stuff – in particular, how CBD is absorbed and broken in the body – which is best?

Here, we delve into a hugely important (and often overlooked) part of using CBD: bioavailability. We’ll go over each method of CBD administration and how the body breaks it down to hopefully let you know how to make the most out of every last drop.  

What is CBD?

Cannabidiol (CBD) is one of many active ingredients found in the Cannabis sativa plant. Unlike tetrahydrocannabinol (THC) – the plant’s mind-altering molecule – CBD is a non-psychoactive cannabinoid, meaning it cannot get you high. ​​

Currently, CBD (in the form of the drug Epidiolex) is recognised as an effective treatment for rare forms of epilepsy. CBD also appears to have promising therapeutic potential in treating numerous other mental and physical health conditions, including anxiety, inflammatory pain, fibromyalgia, and many more. 

CBD interacts with our endocannabinoid system (ECS), a cell-signalling network involved in regulating countless biological processes – namely, our mood, appetite, sleep, immune activity, memory, and more. Although it isn’t fully understood how CBD works, it is believed to support the function of the ECS, helping to maintain biological stability in the body.

Because of its widespread health benefits, a growing number of people are choosing to incorporate CBD into their lives as a daily health supplement. Despite the many science-backed benefits of CBD, some people may have found that CBD hasn’t worked for them. Whilst there are many reasons why your CBD might not be working, it might be that the importance of the product’s bioavailability is being overlooked.

Bioavailability: an overview 

By definition, bioavailability “is the potential for uptake of a substance by a living organism…usually expressed as the fraction that can be taken up by the organism in relation to the total amount of the substance available.” Put simply, it’s how much of an active ingredient the body can absorb into the bloodstream. 

For CBD to be therapeutically effective, it needs to reach receptors in the ECS via the bloodstream. So, take a single dose of CBD; the more of it that the body is able to absorb, the greater its effect – and the less of the active ingredient is needed for the effects to be felt. 

From a consumer perspective, bioavailability pretty much translates to how much bang you get for your buck. The greater the bioavailability of a product, the more you get out of it.    

How to take CBD – which is best?

The absorption of CBD is almost entirely dependent on its route of entry into the body, better known as the method of administration or the delivery method. Understanding how CBD gets into the bloodstream can help you to determine which delivery method is best for you and work out your desired dosage. So, let’s take a look at the bioavailability of some of the most popular ways to take CBD:

CBD oil

The purest and most popular way to take CBD is in the form of an oil. It is administered sublingually, where a few drops are placed and held under the tongue before it is swallowed. Since this is a very capillary dense region, the sublingual method allows for speedy absorption. And because it bypasses the liver and digestive system, it delivers CBD to the bloodstream in around 15-30 minutes, with blood levels peaking within about 2 hours. 

Although research into the bioavailability of CBD oil hasn’t been hugely conclusive, it is estimated that this figure is around 13-19%. However, some studies have found the sublingual delivery method to have a bioavailability of up to 35%.

Since taking CBD oil sublingually has a relatively high bioavailability and rapid onset of action, it’s likely best for those seeking immediate relief from their symptoms. The beauty of CBD oil is that you control the dropper; you can up your dose on the days you need it most. Keen to give it a go? Take a look at our guide to the different types of CBD oil

Oral CBD

CBD capsules, gummies, snacks, coffees, and drinks are proving to be hugely popular ways to consume CBD. They’re great for those looking to avoid the strong taste of CBD oil, but they may not be quite as effective. This is because taking CBD orally has one of the lowest bioavailabilities of all delivery forms, estimated at around 6%.

Why is this? Well, CBD is fat-soluble, meaning it doesn’t dissolve in water very easily. As a result, much of it is broken down by digestive enzymes in the stomach before it has a chance to be absorbed into the bloodstream. Consequently, peak levels of CBD tend to be lower when taken orally. 

That said, oral CBD does have its benefits. One animal study, in particular, found that CBD consumed orally stays in the body for 4.2 hours, whereas injected CBD was only 3.3 hours. These findings suggest that CBD capsules and gummies, for instance, may have a longer-lasting effect than products with other methods of administration. So, CBD-infused edibles may be best for those after a consistent daily dose that builds up in your system over time, rather than immediate symptomatic relief.   

Vaping CBD

Inhalation is possibly the most effective and efficient way of getting CBD into the bloodstream. Again, this method bypasses the digestive system and is absorbed through the lungs, directly into the bloodstream. Inhalation includes both smoking and vaping, but since CBD flower cannot be legally obtained in the UK, we will instead focus on what CBD vapes have to offer. 

How do CBD vape products work? When you inhale from a vape pen, CBD-infused e-liquid is heated and atomised to produce a vapour. Since the CBD goes directly into the lungs, it has a rapid onset of action – between 10 and 20 minutes.

Inhalation has a high bioavailability. The exact value isn’t known, but it is estimated to be anywhere between 31-56%. Since a vape pen is readily transportable, many people choose to opt for vaping CBD on the move for immediate relief. However, despite its impressive bioavailability, the long term effects of vaping are not yet known so approach this method with caution. 

Topical CBD

Topical CBD products, such as balms, gels, creams, and patches, are proving to be hugely popular amongst those who wish to target specific aches and pains. Transdermal delivery provides a slow and steady dose of CBD through the skin barrier, which is thought to offer direct relief to the skin, joints, or muscles.

But again, the fat-soluble nature of CBD complicates this delivery method. Our skin has many layers, some of which are water-soluble and act as a barrier to absorption. There hasn’t been a huge amount of research into the exact bioavailability of topical CBD products, but it is believed to be pretty low – around 3%.

Instead, many brands add their CBD to an ethanol carrier in their topical products. This makes CBD more water-soluble, which could make it nearly 4x more absorbable by the skin. It may not be the most effective way of taking CBD, but the transdermal delivery method is ideal for those seeking a slow, controlled, and targeted dose throughout the day. 

Ways to increase the bioavailability of CBD

If you’re looking to make the most of your CBD products, there are some things you can do to optimise their bioavailability.  

Hold CBD oil under your tongue for longer

Although some people like to add their CBD to coffee or smoothies, you get far more for your money by taking it sublingually. Holding CBD drops under the tongue for at least 60 seconds allows more time for the CBD to be absorbed before it is swallowed. The longer it is held there the more that is absorbed, in theory.  

Take CBD with food

For oral CBD, either in the form of CBD-infused edibles or CBD oil, the best thing you can do is take it with food – and not on an empty stomach! Because CBD is fat-soluble, consuming it alongside a meal or snack rich in healthy fats allows it to dissolve in the food and, in turn, increases its absorption. Researchers have even shown that giving CBD to animals in a fed state increases its bioavailability 3-fold.

Try a water-soluble CBD product

With the growing CBD industry, several brands have now ventured into the world of water-soluble CBD, typically in the form of tinctures, sprays, or powders. Water-soluble CBD undergoes a process of emulsification, which allows for greater absorption throughout the digestive system and into the bloodstream. 

Up your CBD dose

Though it may seem obvious, increasing your dose of CBD can help your body to get more of it – and not just because you’re taking more! Higher doses actually favour better absorption. For instance, increasing a dose from 5 mg to 10 mg has been shown to double absorption, whereas increasing it from 10 mg to 20 mg can triple absorption.  

Try broad-spectrum or full-spectrum CBD

A broad- or full-spectrum CBD oil contains many other cannabinoids, terpenes and flavonoids. Not only does the combination of these allow you to benefit from the entourage effect, but some cannabis compounds can even increase the bioavailability of your CBD product. Various terpenes, such as limonene or myrcene, can act as fatty oils that enhance the absorption of CBD in the body.    

A summary of CBD delivery methods

Now that we’ve told you all there is to know about CBD and bioavailability, let’s sum it all up.

SublingualTaking CBD oil sublingually gives a bioavailability of about 13-19%, but this figure could be improved by holding it under the tongue for longer. With a rapid absorption rate, this delivery method is ideal for those wanting immediate relief.

OralEdible CBD products, such as capsules or gummies, have a low bioavailability of approximately 6% unless taken with food. They may only offer low doses, but they have a longer-lasting effect than other products.

InhalationVaping CBD has an impressive bioavailability, estimated to be around 31-56%. Despite its rapid onset of action and high rate of absorption, the effects of CBD vape pens on lung health are not yet known.

TopicalDespite its low absorption rate (roughly 3%), topical CBD products provide a slow and steady dosage. This is ideal for people seeking consistent delivery of CBD to a specific, problem area.

Looking to branch out and try some new CBD products? Take a look at our ultimate guide to navigating the many ways to take CBD.

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