Cellular absorption is the final step of nutrient uptake — the point at which a nutrient that has entered your bloodstream is actually taken into and used by your cells. Bioavailability is the broader measure of how much of a nutrient reaches circulation in a usable form. A supplement can pass through your gut and still be poorly delivered to cells, which is why how a nutrient is delivered can matter as much as how much of it a label promises.
I am not a physician, and I want to be clear about that from the first paragraph. I am a Maryland State Certified Residential Appraiser — my professional life is spent examining evidence, weighing sources, and reaching defensible conclusions I have to sign my name to. When I became interested in supplement science, I approached it the same way: read the studies, separate what is demonstrated from what is claimed, and organize it so an ordinary person can make an informed decision. This guide is the result. It cites its sources so you can check every claim yourself.
I also disclose, on every page of this site, that I am a compensated Founding Member and Brand Ambassador for THREE International, a company built around absorption technology. That relationship is why I know this topic in depth. It is also why I am careful to distinguish, throughout this guide, between independent peer-reviewed science and any single company's marketing — including THREE's.
What Is Cellular Absorption?
When you take a supplement, the nutrient has to complete a journey before it does anything useful. It must survive stomach acid and digestive enzymes, cross the wall of the small intestine, enter the bloodstream, travel to the tissues that need it, and finally be taken up by individual cells. Most absorption studies only measure one early stage of that journey — whether the nutrient crosses the gut wall into the blood. Cellular absorption refers to the last stage: uptake into the cells themselves.
This distinction matters because the two are not the same. A nutrient can show up in a blood test yet still be delivered inefficiently to cells, and a nutrient can be destroyed in digestion long before it ever reaches the blood. When a supplement company talks about "cellular absorption technology," what they are describing is an attempt to protect a nutrient through digestion and improve its delivery all the way to the cellular endpoint — not just its appearance in the bloodstream.
What Does Bioavailability Mean in Supplements?
Bioavailability is the proportion of a nutrient you consume that reaches systemic circulation in an active, usable form. A nutrient with 90% bioavailability delivers far more of its labeled dose to your body than one with 10%. Bioavailability is not a fixed property of a nutrient — it changes with the delivery format, the dose, your digestive health, and your baseline nutritional status.
The word gets used loosely in marketing, so it helps to be precise. In pharmacology, bioavailability has a specific meaning: the fraction of an administered dose that reaches circulation unchanged. For a supplement, the practical question is similar — of everything in the capsule, how much actually becomes available for your body to use?
Several factors move that number:
- The nutrient itself. Some nutrients are absorbed easily; others are fragile, fat-soluble, or poorly soluble and absorb badly in standard forms.
- The delivery format. A plain tablet, a capsule, a liposomal liquid, and an emulsified softgel can produce very different blood levels of the same nutrient.
- The dose. Some nutrients, like vitamin C, have absorption that saturates — past a certain dose, the percentage absorbed drops sharply.
- The individual. Stomach acid, gut health, age, and medications all shift how much you absorb.
How Are Supplements Absorbed? The Four Barriers
To understand why delivery technology exists at all, it helps to see the obstacles a nutrient faces. There are four:
1. The digestive gauntlet
Stomach acid and enzymes are designed to break things down. Fragile compounds — certain antioxidants, some forms of vitamin C, sensitive peptides — can be partly destroyed here before absorption even begins.
2. The solubility problem
Many valuable compounds are fat-soluble (curcumin, CoQ10, resveratrol) and dissolve poorly in the watery environment of the gut. If a compound will not dissolve, it largely will not absorb, regardless of the dose on the label.
3. The intestinal wall
The gut lining is selective. Some nutrients cross easily through dedicated transport systems; others are actively pumped back out or simply pass through unabsorbed.
4. Delivery to the cell
Reaching the blood is not the finish line. The nutrient still has to be delivered to and taken up by cells. This is the stage that gives this site its name, and the stage most absorption marketing quietly skips over.
Delivery technologies — liposomes, micelles, emulsification, and others — are all attempts to get a nutrient past one or more of these four barriers. The most discussed of them is the liposome.
Liposomal Absorption: How It Works and What the Evidence Shows
Liposomal delivery wraps a nutrient inside a tiny sphere made of phospholipids — the same class of molecule your own cell membranes are built from. This shell can protect the nutrient through digestion and help it reach circulation. Human trials show a real bioavailability advantage for several nutrients — most robustly vitamin C, CoQ10, glutathione, and curcumin — but the size of the advantage varies widely by nutrient and by manufacturing quality, and it is not universal.
A liposome is a microscopic bubble whose wall is a phospholipid bilayer. Because that wall mimics the structure of your own cell membranes, liposomes can shield their cargo from digestive breakdown and improve its passage into the body. That is the mechanism. The more important question is what controlled human studies actually find.
What the peer-reviewed evidence says
The honest picture is that the evidence is genuinely stronger for some nutrients than others.
| Nutrient | What controlled studies show | Strength of evidence |
|---|---|---|
| Vitamin C | A 2025 scoping review found the majority of human studies reported higher blood levels from liposomal forms, with peak concentrations and total absorption both increased over standard vitamin C. A 2024 placebo-controlled crossover trial reported roughly a quarter-higher peak plasma levels. | Strongest |
| CoQ10 | A 2025 double-blind, placebo-controlled randomized trial reported a 31% higher peak concentration and a 23% higher total exposure (AUC) for liposomal versus standard CoQ10. | Strong |
| Glutathione | Studies indicate liposomal delivery helps protect this fragile antioxidant from digestive breakdown, supporting better delivery than unprotected forms. | Moderate |
| Curcumin | Notoriously poorly absorbed in its raw form; delivery systems that improve its solubility measurably raise absorption. This is one of the clearest cases where format changes outcome. | Moderate |
| B vitamins | Generally absorb well already through standard delivery, so a liposomal premium adds little for most people. | Advantage small or absent |
| Liposomal NAD/NMN | Testing has found products with little or no detectable active compound, and no robust evidence the liposomal claim improved absorption. | Weak / caution |
Sources: Carr et al., Basic & Clinical Pharmacology & Toxicology (2025) liposomal vitamin C scoping review; Jäger et al., Frontiers in Nutrition (2025) liposomal CoQ10 RCT; systematic reviews of enhanced vitamin C delivery (2025); independent product testing analyses (2026).
What makes a liposomal product actually work
- A named phospholipid source (such as phosphatidylcholine) rather than a vague "liposomal" banner.
- Appropriate particle size. Functional liposomes generally fall in the 50–200 nanometer range; products outside that range may lack a real delivery mechanism.
- Manufacturing transparency and third-party testing confirming the active is actually encapsulated, not merely mixed alongside empty vesicles.
- Realistic claims. "100× absorption" banners are a warning sign, not a selling point.
Liposomal vs. Regular Supplements: When the Premium Is Worth It
Putting the evidence together yields a practical rule. For hard-to-absorb nutrients — high-dose vitamin C, glutathione, curcumin, CoQ10 — from a transparent, tested brand, the delivery premium can be justified because the format genuinely changes how much reaches you. For nutrients that already absorb well, or for categories with weak evidence and quality problems, paying two to three times more rarely makes sense. Delivery technology is a tool for specific problems, not a universal upgrade.
Does Supplement Absorption Change With Age?
It can. Stomach acid production often declines with age, gut function changes, and common medications can interfere with the uptake of specific nutrients. This is one reason delivery format is discussed more often in the context of adults over 50 — when baseline absorption may already be reduced, the efficiency of delivery can matter more.
None of this means older adults cannot absorb nutrients well, and it is not a reason to assume a problem. It is a reason that the same nutrient, in a better-delivered form, may make a larger practical difference for someone whose baseline absorption has declined than for a 25-year-old with a robust digestive system. As always, individual circumstances vary, and questions about your own nutritional status are worth raising with a physician who can test for it.
A Case Study in Delivery: THREE International's Approach
Because I work with THREE International, I can describe how one company has built its entire product line around this single idea — and I will hold it to the same evidentiary standard as everything above.
THREE International launched in the spring of 2023, founded by CEO Daniel Picou and guided by Chief Scientific Officer Dr. Dan Gubler, a Caltech-trained phytonutrient chemist. The company's defining decision, in its own words, was to compete on delivery rather than ingredients — the position that "it's not what you eat, but what you absorb." Its products use what it calls Cellular Absorption Technology, and the company publishes in-house Caco-2 cell absorption figures for its formulas.
In its June 2026 technical overview, THREE names twelve distinct delivery approaches used across the line, matched to specific products. Rather than a single "liposome" story, the formulations draw on a range of mechanisms: a yeast-derived glycoprotein matrix (Vitalité); liposomal encapsulation (Purifí, Revíve, Imúne, Éternel); micelle technology (Revíve); polyphenol complexation (Vitalité, Collagène, Éternel, GLP THREE, Kynetik); hydrolysis and micronization for peptides and collagen (Collagène, Éternel); enzyme pre-digestion (Vitalité, Purifí); chelated amino acids (Imúne); and fulvic acid and chlorophyllin as nutrient carriers (Purifí). These are the mechanisms behind the published absorption figures. Whether each one delivers the stated benefit in a person is exactly what the Caco-2-versus-human distinction throughout this guide is meant to keep clear: a named, plausible delivery mechanism is a reason a formula could absorb better, not proof that it does in your body.
Here is the balanced reading. THREE's core thesis — that delivery format materially affects how much of a nutrient reaches your cells — is well supported by the independent science summarized above. Its use of liposomal encapsulation for compounds like curcumin and resveratrol is mechanistically sensible, because those are exactly the poorly-soluble compounds where delivery matters most. At the same time, the specific absorption percentages a company publishes from its own laboratory assays are in-house data, not independent human trials, and should be read as directional evidence about a formulation rather than as guaranteed outcomes in your body. I apply that same distinction to every product I review on this site.
If you want the product-by-product detail — ingredients, the published figures, what the underlying research does and does not establish, and where I think the claims are strong versus where they outrun the evidence — that is what the individual reviews are for.
Frequently Asked Questions
The Cellular Absorption Answer Library
This guide is the overview. For focused answers to specific questions, the library below goes deeper on each one — every page cites its sources and links back here.
The Bottom Line
Bioavailability is the difference between a supplement that works on paper and one that works in your body. The science is clear that delivery format genuinely changes how much of certain nutrients reaches you — and equally clear that the effect is nutrient-specific, quality-dependent, and often overstated in marketing. The most useful thing you can do as a consumer is stop reading labels for dose alone and start asking how much of that dose is actually delivered.
That is the entire premise of this site. Every product review here is an application of the principles on this page. If you found this guide useful, the individual reviews show the same evidence-first method applied to specific formulas — including a company, THREE International, that has staked its whole identity on the ideas above.