Merriam-Webster defines bioavailability as “the degree and rate at which a substance is absorbed into a living system or is made available at the site of physiological activity.” First used in this expanded form in 1977 from “bioavailable,” the term was used to address how we measure a body’s intake of nutrients from food. These days, the term “CBD bioavailability” is taking hold as regulating bodies attempt to understand how to issue proper dosing guidelines, beyond explaining that every body metabolizes CBD and other substances differently, and therefore, should be eased into.
The very first studies are finally coming into the mainstream, providing better understanding and science to guide the conversation. CBD bioavailability matters as it is the percentage of CBD the body actually absorbs into the bloodstream determining how effective it will be. The more uptake, the more potent CBD’s effects will be and is primarily determined by the type of CBD product a person takes as well as how they take it. CBD bioavailability is currently understood as follows (method/percentage of uptake into bloodstream/amount of time to take effect:
1) Swallowed/ingested, 4 to 20 percent with a median 6 percent, 30 minutes to 2
2) Sublingually (under the tongue), 35 percent, 15 to 25 minutes.
3) Rectally, 8 to 50 percent, 20 to 60 minutes.
4) Inhaled or vaporized, up to 56 percent, 10 to 20 minutes.
5) Topically, up to 45 percent and stays localized, typically 24 to 45 minutes.
(Using this method, CBD does not enter the bloodstream, but connects with local
cannabinoid receptors via the skin’s pores.)
A 2019 study conducted by the University of Minnesota explored “Food effect on pharmacokinetics of cannabidiol oral capsules in adult patients with refractory epilepsy.” Pharmacokinetics is “the branch of pharmacology concerned with the movement of drugs within the body” and is measured in four stages: absorption, distribution, and the two methods of elimination, metabolism and excretion. Each of these processes are influenced by how a drug or substance is administered (form) and body organ function.
In simpler words, the study explored how eating a typical, high-fat food in conjunction with CBD - in this study breakfast burritos - encouraged better absorption than when CBD was taken without food. That said, since various meals contain variable fat levels - a concern in real life and when controls aren’t in place - this fat content variance can be presumed to affect how much CBD uptake would actually occur by introducing different meals.
When related to a specific health concern, for the purpose of this study epilepsy, determining the proper CBD bioavailability is critical as too little can leave patients vulnerable to seizures.
Therefore, determining a dosing method that ensures consistent CBD levels in the bloodstream is of utmost importance. The three predominant takeaways were:
1) CBD Uptake was vastly increased when taken with foods high in fat.
2) When compared to fasting, taking CBD in conjunction with high-fat foods
increased the amount of CBD in the body by four times greater than without and the
maximum CBD recorded in participants’ bloodstream.
3) Consistent with other studies, no cognitive differences were registered. An additional study’s findings exploring various challenges with CBD delivery was released online in August 2020 and can be found in detail at:
Citations: University of Minnesota. "High fat foods can increase oral cannabidiol
absorption into the body." ScienceDaily. ScienceDaily, 13 August 2019.