What “bioavailability” actually means
Bioavailability is the proportion of an ingested substance that reaches systemic circulation in an active, usable form. A 500 mg dose that is 10% bioavailable delivers roughly 50 mg of active substance to the bloodstream — the other 450 mg was destroyed, excreted, or never absorbed at all.
Two separate barriers determine this number:
Solubility— many bioactive compounds, including curcumin, CoQ10, and several carotenoids, are poorly soluble in water. The intestine absorbs primarily through an aqueous environment, so a compound that won't dissolve struggles to cross the gut wall regardless of how much is swallowed.
Stability — even water-soluble compounds can be chemically fragile. Glutathione, for instance, is a tripeptide that digestive enzymes (particularly gamma-glutamyltransferase) break apart into its three constituent amino acids before it can be absorbed intact.
Standard tablets and capsules address neither barrier directly — they simply deliver the raw compound and rely on the digestive system to do the rest. When the compound is fragile or insoluble, most of the dose is lost before absorption.
How liposomal encapsulation addresses this
A liposome is a spherical vesicle built from a phospholipid bilayer — structurally similar to the membrane surrounding every cell in the human body. When a bioactive compound is encapsulated inside this bilayer, it travels through the digestive tract inside a protective shell rather than exposed to stomach acid and enzymes directly.
A 2016 pharmaceutical review in Journal of Drug Targeting on liposomes and oral drug absorption describes several mechanisms by which this improves uptake: liposomes adhere more readily to intestinal membranes, form mixed-micelle structures with bile salts that increase the solubility of poorly-soluble compounds, and are more readily taken up through lymphatic absorption pathways than free compounds swallowed directly.
The effect has been measured directly in several compounds. A 2014 study in rats found that capsaicin encapsulated in a phospholipid liposome achieved a 3.34-fold increase in relative bioavailability compared to the free compound. A separate study on griseofulvin (an antifungal with poor water solubility) found that liposomal encapsulation roughly doubled the area-under-curve — a standard pharmacokinetic measure of total absorption — compared to a plain aqueous suspension, with smaller liposomes (under 400 nm) outperforming larger ones.
A 2019 review in the Journal of Drug Delivery Science and Technologyon drug-phospholipid complexes notes that this absorption-enhancement mechanism mirrors how the body already absorbs dietary fats and fat-soluble nutrients — phospholipid carriers aren't introducing a foreign absorption pathway, they're routing the compound through one the gut already uses.
This is a physical-chemical description of how a delivery format behaves, not a claim about health outcomes. Whether improved plasma delivery translates into a felt or measured health benefit depends on the specific compound, dose, and what that compound does once absorbed — a separate question from the bioavailability question, and one this article does not attempt to answer for every ingredient.
Case study 1: Curcumin — where format genuinely changes the outcome, and where the marketing outruns the data
Curcumin, the primary bioactive in turmeric, is a well-studied example of poor natural bioavailability. It is practically insoluble in water and metabolized quickly, so plain curcumin taken orally is often undetectable in blood plasma at all.
This has produced a genuinely crowded field of “bioenhanced” curcumin formats — not just liposomal, but phytosomes (curcumin bound to phosphatidylcholine), cyclodextrin complexes, piperine-combination formulas, and proprietary blends like BCM-95®. A 2021 human crossover study published in The Journal of Nutrition compared five different turmeric formulations at clinically relevant doses and found that bioavailability varied substantially by formulation — the type of enhancement technology used changed the outcome, not just the raw curcumin content on the label.
Individual studies on specific formats support this. A pilot crossover study on BCM-95® found it produced measurably higher plasma curcumin than both plain curcumin and a curcumin-lecithin-piperine combination in human volunteers. A separate crossover study comparing a phytosome formulation, a cyclodextrin formulation, and standard curcumin extract in twelve healthy volunteers found meaningful differences between formats.
The honest caveat:this is a genuinely competitive field with several credible enhancement technologies, not a case where liposomal is a settled “best” answer. Comparative head-to-head human trials between liposomal curcumin specifically and every other bioenhanced format are limited, and manufacturers of each technology naturally cite the studies most favorable to their own format. Anyone evaluating a curcumin product should look for the specific pharmacokinetic data behind that exact product, not the enhancement category in general.
Our own Liposomal Curcumin formulation (250 mg per 7 mL serving) was tested against this same benchmark. In a comparative trial conducted at a German laboratory (n=20), the liposomal formulation reached an area-under-curve bioavailability 46.79 times higher than a standard 250 mg curcumin tablet; at the 2-hour mark specifically, plasma curcumin was roughly 30 times higher. That's a single-timepoint snapshot rather than the full-exposure comparison — the 46.79× figure is the more complete measure. This, too, was manufacturer-commissioned comparative testing rather than an independently published academic trial.
Case study 2: Glutathione — a real result, and a real methodological critique worth knowing about
Standard oral glutathione supplementation faces a specific, well-documented problem: gamma-glutamyltransferase, a digestive enzyme, breaks the tripeptide into its three amino acid components before meaningful amounts reach circulation intact. This is why oral glutathione has historically been considered poorly bioavailable.
A human pharmacokinetic study published in early 2026 gave twelve healthy subjects a single oral dose of either a liposomal glutathione formulation or plain glutathione and tracked plasma levels over 24 hours using LC-MS/MS. The liposomal formulation reached a peak plasma concentration roughly six times higher than the plain form, with a bimodal absorption pattern and plasma levels still elevated above baseline at 24 hours.
This is worth reading alongside a published critique of a related glutathione bioavailability study, raised by a competing supplement manufacturer's research lead in early 2026. The critique's core point: a widely cited liposomal glutathione study measured glutathione increases in whole blood rather than isolated plasma or cell contents specifically — and whole blood is a mixture of plasma and blood cells. The critique argues that demonstrating a compound survives digestion and reaches the bloodstream is not the same as demonstrating it reaches the inside of cells, which is where glutathione performs its intracellular antioxidant function.
This is a fair methodological point and a useful example of how bioavailability data can be technically accurate while still leaving an open question about what actually matters physiologically. We're including it here rather than only citing the favorable study, because presenting the strongest available evidence alongside its known limitations is the standard we hold ourselves to.
The same liposomal technology and dose used in our own Liposomal Glutathione formulation (500 mg per 7 mL serving) has been tested this way. In a seven-day comparative trial conducted at a German laboratory (n=20, dosed at baseline, day 3, and day 7), the liposomal formulation reached plasma glutathione levels 63.62 times higher, by area-under-curve, than a standard 500 mg glutathione tablet at the same dose. This was manufacturer-commissioned comparative testing rather than an independently published academic study — the same caveat about study design applies here as to the research above.
Case study 3: Iron — the tradeoff is tolerability as much as absorption
Standard ferrous sulfate, the most common iron supplement form, has a well-established bioavailability ceiling: typically 10–20% of an ingested dose is absorbed, with the rest interacting with dietary inhibitors like phytates and tannins, or simply passing through unabsorbed. It's also associated with a well-documented pattern of gastrointestinal side effects — nausea, constipation, and stomach discomfort — that reduces how consistently people actually take it.
A 2026 randomized controlled trial in infants with iron-deficiency anemia, published in the Journal of Comprehensive Pediatrics, compared liposomal iron against ferrous sulfate and used a lower elemental iron dose in the liposomal arm (15 mg/day vs. 25 mg/day) specifically because prior pharmacokinetic data indicated liposomal iron requires less elemental iron to achieve comparable therapeutic effect. A separate systematic review comparing liposomal iron against ferrous bisglycinate (a chelated iron form) found generally favorable tolerability and comparable-or-better absorption profiles for the liposomal format across the studies it reviewed. For more on iron deficiency prevalence and testing, see our iron deficiency in Europe article.
For context on chelated iron more broadly: earlier research on iron amino acid chelate (marketed as Ferrochel®) found iron absorption from the chelate was roughly twice that of ferrous sulfate in a controlled comparison across 74 subjects — a reminder that liposomal encapsulation is one of several legitimate strategies for improving iron absorption, not the only one.
Our own Liposomal Iron formulation (15 mg per 5 mL serving) uses this same delivery technology at this same dose. In a comparative trial conducted at a German laboratory (n=30, three arms of 10), the liposomal formulation reached iron levels 397.7 times higher, by area-under-curve, than a 15 mg non-liposomal iron powder, and 44.4 times higher than a 40 mg iron tablet combined with 40 mg vitamin C. As with the glutathione figures above, this was manufacturer-commissioned comparative testing, not an independently published trial.
Iron is the one ingredient in this article where format changes matter for an authorized health claim. Iron carries EU-authorized claims for normal cognitive function, immune function, and reduction of tiredness and fatigue — but only when a product supplies at least 15% of the Nutrient Reference Value per daily serving. A format that improves absorption doesn't change what claim is legally available; it changes how much elemental iron is actually needed in the formula to reliably clear that threshold in the people taking it.
Delivery formats aren't interchangeable
A practical comparison
| Format | Mechanism | Best suited for | Key limitation |
|---|---|---|---|
| Standard tablet/capsule | Disintegration + passive absorption | Water-soluble, stable compounds (many B vitamins) | No protection from GI degradation; poor for fragile or insoluble compounds |
| Liposomal (phospholipid bilayer) | Encapsulation mimicking cell membrane structure; bile-salt micelle formation; lymphatic uptake | Fragile compounds (glutathione), and combined with other technology for insoluble ones (curcumin, CoQ10) | Manufacturing cost and complexity; liposome stability varies by formulation quality |
| Phytosome (phospholipid complex) | Direct molecular binding of compound to phosphatidylcholine | Insoluble polyphenols (curcumin, certain flavonoids) | Different mechanism from liposomal encapsulation — often confused with it |
| Chelated minerals (e.g., bisglycinate) | Mineral bound to an amino acid, changing the absorption pathway used | Minerals prone to poor absorption or GI inhibition (iron, magnesium, zinc) | Absorption gains are real but typically smaller than liposomal or nanoemulsion for the same mineral |
| Nanoemulsion | Sub-micron oil droplets stabilized by surfactants/phospholipids | Fat-soluble compounds needing rapid, high-magnitude absorption gains | Formulation stability and oxidation risk over shelf life; less established for water-soluble actives |
No single format is universally “best” — the right choice depends on the specific compound's solubility and stability profile. For context on chelated mineral formats specifically, see our article on chromium and blood glucose.
What this means when evaluating a supplement
- Check whether the delivery format matches the ingredient's actual limitation. A liposomal B12 product, for instance, is solving a problem B12 doesn't have to nearly the same degree glutathione or curcumin do — B12 is comparatively well-absorbed in standard forms for most people (absorption issues are more often related to intrinsic factor and stomach acid levels, not molecular fragility).
- Look for pharmacokinetic data on the specific product, or at minimum the specific formulation technology — not just the word “liposomal” on the label. As the curcumin research above shows, format-within-format matters.
- Separate the bioavailability question from the health-outcome question. Better absorption is a measurable, physical fact. What that improved absorption does for how you feel is a separate question, ingredient by ingredient, and not one this article — or any format comparison — can answer in general terms.