What Is Bioavailability?

Bioavailability refers to the percentage of any substance that reaches its biological destination. 

A product that’s highly bioavailable, for example, will reach the areas it’s supposed to mostly intact. Any product whose bioavailability is above 20% is actually doing pretty well — for example, CBD’s oral bioavailability is often 13-19%. 

How Bioavailability Works

A product’s bioavailability also differs depending on how you take it. When it comes to skincare, topical skincare products tend to have a higher bioavailability than their oral counterparts. If you want to directly improve your skin’s health, consider directly applying products to your skin! Intuitive enough, right?

Let’s look at a few practical examples. Vitamin C is an antioxidant with numerous skin benefits, but for best results, you’ll want to apply a form of vitamin C called L-ascorbic acid directly to your skin. The same concept is seen with the skin-boosting B vitamin niacinamide — its regenerative properties are best accessed when applied directly. 

Other factors that can influence bioavailability include a substance’s molecular structure, molecular mass, and even their electrical charge. In general, smaller molecules are better absorbed than larger ones. 

While topical application is the most effective type of application, supplements can play a critical role to a well-rounded and holistic approach to skincare. One study found that oral collagen supplementation “improve[d] skin hydration, elasticity, roughness, and density.”

The Different Types of Biovailability

Here’s some good news: premium skincare products come with bioavailability-boosters built-in. 

Terpene-rich essential oils are among the best natural permeability enhancers — that’s because most terpenes have an exceptionally low molecular mass that allows them to deeply saturate the skin. Skincare products that are micro- or nano-emulsified work through a similar mechanism. 

Other permeability enhancers include solvents, phospholipids, occlusives, and exfoliants. Physical exfoliants (think sugar scrubs) can boost your skincare product’s bioavailability, too! Some people go so far as to derma-roll their product of choice into their skin, which allows it to make it through the stratum corneum (the skin’s top layer). 

And there’s one more way to boost bioavailability that deserves a mention: toning. Toning your skin improves its permeability and allows moisturizers to sink in more deeply than they would otherwise.

CBD’s Topical Bioavailability

CBD’s topical bioavailability is surprisingly low — the CBD you put on your skin doesn’t really make it into your bloodstream, and it certainly doesn’t have any effect on your brain. 

But that doesn’t mean topical CBD isn’t effective. CBD salves and other topicals still have plenty of health benefits, and that’s because they activate specialized endocannabinoid receptors located within the skin itself. 

And when these receptors are activated, all sorts of good things begin to happen: inflammation is minimized, pain levels go down, oil production is normalized, et cetera. For a more in-depth look at the endocannabinoid system’s role in skin health, check out this excellent presentation from Phytecs

To sum things up, CBD’s topical bioavailability honestly isn’t anything to get excited about. But CBD’s role within a healthy skincare routine most definitely is.