When people talk about CBD, the focus almost always falls on concentration. How many milligrams a product contains, what percentage, whether it’s an isolate or full-spectrum. But there’s a variable that affects efficacy just as much — if not more — than concentration: bioavailability. In other words, how much of the CBD you take actually reaches the bloodstream and, from there, the target tissues.
The answer changes substantially depending on the format. Sublingual oil, nanoemulsions, water-soluble powder, liposomes: these are not aesthetic variations of the same product. They are distinct delivery systems, each with its own chemistry, production process, and absorption profile.
The core problem: CBD doesn't like water
CBD is a lipophilic molecule — it binds to fats, not water. The human body is mostly aqueous, and raw CBD ingested as-is meets strong resistance: first-pass hepatic metabolism degrades a large portion of the molecule before it can enter circulation. Pharmacokinetic studies estimate the oral bioavailability of pure CBD between 6 and 13%. Sublingual oil emerged from this limitation and remains the most widespread format: CBD dissolved in a carrier oil — typically coconut MCT, hemp, or olive oil — is held under the tongue for 60 to 90 seconds before swallowing, allowing the capillary-rich sublingual mucosa to absorb it directly into the bloodstream, partially bypassing hepatic metabolism. Bioavailability through this route rises to between 12 and 35%, with an onset of 15 to 45 minutes, though individual variability is high: mucosal thickness, salivation, and even the preceding meal can cause absorption to fluctuate considerably from person to person.
Nanoemulsions and water-soluble powder: the size revolution
Nanoemulsions represent the most widespread technical standard in next-generation CBD products. The principle is to reduce CBD — dispersed in tiny lipid droplets — to nanometric dimensions, typically below 100 nanometers in diameter. Particles that small have an enormously greater contact surface area and cross the intestinal mucosa far more efficiently. Production relies on high-pressure or sonication processes: CBD is emulsified with a surfactant in an aqueous phase and then reduced by mechanical force to the target size. The result is a liquid that mixes with water without separating and can be added to beverages, syrups, or topical formulas. Estimated bioavailability falls between 40 and 60%, with an onset that can drop below 20 minutes.
Water-soluble powder is, in most cases, a nanoemulsion subjected to spray drying: the process removes water and converts the product into a stable, easily measurable powder. Some formulations use cyclodextrins as carriers — ring-shaped molecules capable of encapsulating CBD and making it water-soluble without emulsification. The advantage over liquid nanoemulsions is stability: powders resist oxidation better and integrate more easily into capsules, tablets, and nutraceutical products, with comparable bioavailability and an onset of 20 to 45 minutes.
Liposomes: when the carrier mimics the cell
Liposomes are spherical vesicles composed of phospholipid bilayers — the same structure as cell membranes. CBD is encapsulated inside this structure and, once ingested, liposomes can fuse directly with intestinal cell membranes, releasing the active compound with precision. Production requires high-purity phospholipids — often sunflower or soy lecithin — and controlled hydration and lamination processes, making it more complex and costly than nanoemulsions.
The release profile is the main advantage: liposomes protect CBD from gastric degradation and release it in phases, with an estimated bioavailability of 30 to 60% and an onset of 30 to 60 minutes — slower, but typically more sustained over time. They are best suited for applications where duration of action matters as much as speed: daily wellness supplements, nighttime formulas, products designed for continuous use. Comparing CBD products by looking only at the percentage on the label, while ignoring the delivery system, means comparing things that are simply not comparable.
Exclusive feature article created by World renown Cannabis Author & Authority Mario Catania for CBD Clinic Care International
