Should I smoke or vape CBD, use a CBD oil under my tongue, or take a CBD capsule?
When comparing these three methods of taking CBD, you want to look at safety, absorption, speed of onset, and duration of effect.
First let’s look at absorption rates, which means how much will actually get into your bloodstream and be able to exert medicinal effects. Here are the estimated absorption rates for CBD based on a recent review article:
Inhalation (smoking or vaping): 31%
Sublingual (oil held under the tongue): 22-25%
Ingestion (swallowing capsules or liquid): 13-19%
Another way to look at this how many milligrams will actually get into your bloodstream from a given dose of CBD in each of these routes. For a 30mg dose this translates to:
Inhalation: 9.3 mg
Sublingual: 7 mg
Ingestion: 4.8 mg
Pros and Cons to each method:
While inhalation has the highest absorption rate, it is not ideal for medical usage, as smoking anything can irritate and inflame lung tissue. This is the fastest way to get CBD into your system, usually within minutes, but also has shortest duration of effect.
Ingestion has the lowest absorption rates because the liver filters out most of the CBD on its way from the GI tract to the bloodstream. This is also the slowest method, taking around three hours to reach maximal effect, but gives the most prolonged effect.
The sublingual route bypasses the liver, as CBD is absorbed directly into the blood vessels under the tongue. This route also offers fast entry into your system, and the longer you can hold the CBD oil under your tongue, the more gets into your bloodstream that way. After holding under the tongue, the rest of the CBD oil is swallowed and further absorption via the GI tract occurs. So sublingual use gives the best of both worlds: rapid-onset and a prolonged duration. This combined short-acting and long-acting effect explains why sublingual use can be so helpful for improving sleep issues as it can address problems both falling asleep and staying asleep.
Sublingual CBD is safer than smoking or vaping, and more cost-effective than capsules due to the higher absorption rates. However, for some the taste or texture of CBD oil in their mouth is not palatable, and there are rare reports of stomach upset with CBD oil. In that case CBD capsules may be a better option.
Are whole plant extracts better than CBD isolate?
Products infused with a crystalline CBD isolate, derived and extensively refined from industrial hemp, are available. But single-molecule CBD is thought to be less effective therapeutically than whole plant CBD-rich oil extract. The rich recipe of compounds in medicinal plants exerts healing effects through complementary action. This supports the idea of the "entourage effect", where mixtures of cannabinoids, their co-occurring terpenes, and perhaps other molecules such as flavonoids and stilbenoids, have a greater positive effect than just CBD or THC alone.
Is water soluble CBD better?
Water-soluble forms of CBD are not naturally occurring products. The process of making a fat-soluble compound, such as CBD, soluble in water, involves a process called nano-emulsion. Nano-emulsion uses high frequency ultrasound to induce a process called cavitation, in which small, water soluble spheres (called liposomes) are formed. The CBD molecules are suspended in the liposomes which float in the water. Although some manufacturers make claims about how this form of CBD is "enhanced", there is no data confirming this claim. I personally have not found water-soluble CBD products to be superior than lipid-soluble CBD oil.
Should I take CBD on an empty stomach or with food?
It can be taken either way, but if you want to maximize absorption, or if you have a sensitive stomach, it is best to take CBD with meals or within an hour of eating. A few human studies have found increased absorption from the GI tract when it is taken with food, especially fatty foods. And in rats given CBD orally, when combined with lipids it increased systemic availability by almost threefold!
Does CBD cause QTc prolongation?
Some medications can lengthen the amount of time it takes the heart to recharge between beats, also called QTc prolongation. However, CBD does not cause QTc prolongation. This study looked at a THC/CBD combination medication found it had no effect on any cardiac parameter including heart rate, atrioventricular conduction, or cardiac depolarization. However, THC on its own (not given with CBD) is known to increase heart rate so should be avoided if you have abnormal heart rhythms like atrial fibrillation.
How exactly does CBD affect mood?
CBD has been shown to lessen anxiety in humans, and it does so through actions on a variety of brain receptors but primarily those for serotonin. One exciting study shows CBD has a rapid-onset antidepressant effect on the brain by promoting changes in synaptic plasticity and release of growth factors such as BDNF (brain-derived neurotrophic factor). This study was on mice, but CBD is thought to have similar effects on the human brain which may contribute to its mood-boosting effects, along with actions at the serotonin receptors.