Marijuana edibles continue to spearhead the expansion of the U.S. cannabis industry in 2021 with sales representing a larger year-to-year growth within the market than the total market itself. But despite that explosive increase, or perhaps because of it, many consumers still have questions about the effects and potential risks associated with edibles, particularly regarding potency and on-set time. Both of these factors are affected by a measurement called bioavailability.
This article defines bioavailability, reviews the effect of bioavailability on cannabis edibles, and offers tips for increasing the amount of THC absorbed via ingestion.
What is Bioavailability?
Bioavailability refers to the absorption rate of a given drug and is not unique to cannabis. All pharmaceuticals and even herbal remedies are affected by bioavailability, which is expressed as the percentage of a drug that reaches the circulatory system. When a drug is administered intravenously, directly into the bloodstream, the bioavailability is said to be 100%. But when drugs are administered other ways, like orally or through the skin, some of it is inevitably lost in the absorption process, meaning some amount less than 100% is made biologically available to the consumer. And this bioavailability may be affected by several factors including the consumer’s metabolism, sleep cycle, and what else they’ve eaten.
For reference, the bioavailability of cannabis smoke is roughly 30%.
How Edibles are Absorbed
When cannabis is smoked or otherwise inhaled, THC is taken into the lungs where it passes directly into the bloodstream, and is thus carried to the brain where it does its therapeutic work. But when cannabis is ingested, it takes a much longer route to the bloodstream, passing first through the intestinal tract and later the liver.
In the liver, THC is metabolized from the common delta-9-THC into a slightly different compound called 11-hydroxy-THC. This THC metabolite is thought to be up to 4x more psychoactive in part because it appears to pass the blood-brain barrier more easily. Additionally, this potent compound is released over time from the liver (as opposed to the near-instant effects of smoking) which further accounts for its long lasting effects.
Edibles typically take 1-2 hours to present effects, and those effects last 4-6 hours—longer than any other consumption method. The bioavailability of solid edibles can range between 6-20%.
How Sublinguals are Absorbed
Sublinguals are not meant to be swallowed but rather placed under the tongue where the cannabinoids are absorbed through the porous tissue in the mouth, and into the bloodstream. This same principle is also seen in topical balms in transdermal patches where cannabinoids enter the blood through the skin.
Sublinguals typically present effects faster than edibles because the cannabinoids do not have to pass through a long digestive process. This means that the cannabinoids reaching the brain have also not been digested into 11-hydroxy-THC, and so will likely not present the potent or long lasting effects of edibles.
Bioavailability of sublinguals appears to be much higher due to the oil not being digested, but rather absorbed into the bloodstream via the porous oral tissue. One study from 2012 determined the bioavailability of sublinguals to be about 35%.
How to Increase Bioavailability
One thing you can do to increase bioavailability of solid edibles is to eat them with fat. Cannabinoids are not water soluble, but fat soluble, meaning they bind to lipids. This is why many cannabis recipes call for infusing fatty ingredients like oil or butter. So if hard candies or mints don’t seem to do much, try a baked good, or eat the candy with a little peanut butter.
Conversely, cannabis may also get “lost” in your system if you eat it with too much other food. Consuming cannabis on an empty stomach should increase the amount of cannabinoids metabolized as opposed to, say, swallowing a single gummy for dessert after a large meal.
In 2020, Green Lotus Hemp asked several of their own colleagues how long they recommend keeping sublinguals under their tongue. Most participants responded with around 30 seconds with no one recommending over a minute. However, studies of other sublingual drugs have proposed much longer times.
This trial of sublingual nitroglycerin concluded that some individuals take as long as 10 minutes to absorb an effective dose of medicine. Holding cannabis oil in your mouth for 10 minutes does not sound pleasant, but thankfully, cheek tissue is nearly as absorbent as the tissue beneath the tongue, as is the roof of the mouth, so any excess oil can simply be spread around the inside of the mouth.
While this article proposes several potential math problems for dosing, none of it needs to matter much if you’ve found a dose that works for you. If a 10mg edibles gets you comfortably medicated, then don’t think too much about only absorbing, say, 3mg of it, because whatever is working for you is working. However, if edibles appear inconsistently potent, or your tincture doesn’t seem to work every day, then the problem may have to do with how much THC or other cannabinoids are being absorbed.
The bioavailability of edibles can be increased by ingesting them with fats such as oil or butter (including chocolate), or by ingesting cannabis on an emptier stomach, such as before a meal rather than after. Sublinguals can be more effective if they are kept in the mouth for at least 3 minutes, and as many as 10.
For those still wondering, suppositories have a bioavailability of 70-80%, making them over three times as potent as edibles.
What edible products do you prefer and why? Continue the conversation in the comments below!
What increases absorption of edibles?
Ingesting cannabis with fats should increase absorption because cannabinoids like THC bind with lipids, or fats, in the bloodstream. This is one reason why cannabis is often infused into fatty ingredients like oil or butter.
How is marijuana smoke absorbed?
Marijuana smoke is absorbed directly into the bloodstream via the lungs just like oxygen
What affects edible absorption?
The absorption rate of edibles, or bioavailability, is primarily affected by the consumers metabolic rate including the last time they’ve eaten. Cannabis ingested on an otherwise empty stomach will usually result in more cannabinoids being absorbed.
How does the body absorb edibles?
Edibles are digested through the gastrointestinal tract where cannabinoids are absorbed and sent first to the liver, where THC is converted into a smaller metabolite called 11-hydroxy-THC. This THC metabolite is then passed into the bloodstream to take effect throughout the body.