What does liposomal mean?
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Liposomal means a nutrient or drug is enclosed in liposomes: tiny spheres made of one or more phospholipid bilayers around a watery core1,3. Water-soluble compounds sit in the core and fat-soluble ones in the bilayer1. In medicine the word has a defined standard: liposomal drugs are specified for vesicle size, encapsulated versus free drug and lipid breakdown products1.
What is a liposome?
A liposome is a vesicle formed by a single bilayer or a concentric series of bilayers of amphipathic molecules, such as phospholipids, enclosing a central water compartment1. Phospholipids have a water-loving head and a fat-loving tail, and in water they assemble into these closed bilayers on their own2. Liposomes were first described in the 1960s and became the first nanoscale drug delivery systems to reach clinical use2,3.
The bilayer is usually built from phospholipids or synthetic amphiphiles combined with sterols such as cholesterol, which adjust how permeable the membrane is3. Composition changes behavior: unsaturated phosphatidylcholine from natural sources such as egg or soybean gives a more permeable and less stable bilayer than saturated lipids2. By size and number of bilayers, liposomes are classed as multilamellar vesicles or unilamellar vesicles, which are further split into large and small2.
| Type | Structure |
|---|---|
| Multilamellar vesicle (MLV) | Several concentric bilayers separated by layers of water, like an onion |
| Large unilamellar vesicle (LUV) | One bilayer enclosing a relatively large water core |
| Small unilamellar vesicle (SUV) | One bilayer enclosing a small water core |
What does liposomal mean on a supplement label?
On a supplement, liposomal signals that the maker describes its active ingredient as encapsulated in phospholipid vesicles. What sits behind the word varies widely5. Products described as liposomal in human vitamin C trials included sunflower lecithin with gum arabic and alginate, a fiber-reinforced phospholipid matrix, soybean phosphatidylcholine with rapeseed lecithin, and cold-processed liposome preparations5.
In drug regulation the term has a defined meaning. FDA guidance distinguishes a liposome from an emulsion, a microemulsion and a drug-lipid complex1. For liposomal drug applications it asks for mean particle size and size distribution, zeta potential, the amount of drug inside versus outside the liposomes, encapsulation efficiency and lipid degradation products such as lysolipids1. Those are the measurements that characterize a liposome product1.
| Attribute | What it shows |
|---|---|
| Mean particle size and size distribution | Whether vesicles of the intended size are present, and how uniform they are |
| Contained versus free active ingredient | How much of the ingredient is actually inside the liposomes |
| Encapsulation efficiency and drug-to-lipid ratio | The share of the total ingredient that was loaded, relative to the lipid used |
| Zeta potential | The net surface charge of the vesicles |
| Lipid degradation products | Breakdown such as lysolipids and free fatty acids |
| Size and integrity over shelf life | Whether the vesicles survive storage |
How is liposomal delivery supposed to work in the gut?
The idea is to carry a compound past the barriers that limit its absorption. For vitamin C, regular supplements depend on a sodium-dependent intestinal transporter, while liposomes are absorbed through transporter-independent routes such as endocytosis5.
Digestion works against intact vesicles. Conventional liposomes are damaged by the combined effects of stomach acid, bile salts and pancreatic lipases, which lowers the number of intact liposomes and lets their contents leak4. In one laboratory test cited in a 2019 review, most liposomes held in artificial intestinal fluid for 120 minutes showed irregular shapes and damaged membranes4.
Vesicles that survive can be taken up whole through M cells in the gut lining and passed to the lymph4. That route sets an upper limit, because M cells make up only about 5% of the follicle-associated epithelium and 1% of all intestinal lining cells4. Formulators respond with stabilizing strategies such as adding bile salts to the bilayer or coating the vesicle surface4.
What is liposomal glutathione?
Liposomal glutathione is glutathione, the most abundant antioxidant the body makes itself, enclosed in liposomes6. The best known human study is a one-month pilot published in 2018, in which 12 healthy adults used oral liposomal glutathione at two daily amounts6. Glutathione rose after 1 week, with maximum increases at 2 weeks of 40% in whole blood, 25% in red blood cells, 28% in plasma and 100% in peripheral blood mononuclear cells6.
The design limits what it shows. Results were compared with each participant's own baseline, there was no non-liposomal comparison group, and the authors note that statistical power was limited by the small sample6. The study was funded by a company that supplies liposomal glutathione6.
Is liposomal better than non-liposomal?
Vitamin C is the nutrient with the most head-to-head data. A 2025 scoping review found 10 human studies comparing liposomal with non-liposomal vitamin C, and 9 reported higher plasma levels for the liposomal form, from 1.2 to 5.4 times the peak and 1.3 to 7.2 times the total exposure5. All 10 had industry funding or company-employed authors, none measured urinary elimination, and the formulations, amounts and sampling times differed widely5.
Higher blood levels have not shown clear added effects. In a 2016 randomized crossover study of 11 adults, liposomal vitamin C produced blood levels above regular oral vitamin C but below intravenous vitamin C, and all three gave similar protection against oxidative stress in a forearm blood-flow test7. The review concluded that whether the liposomal form gives clinically relevant differences remains to be explored5.
Why do liposomes break down on the shelf?
Liposomes are chemically fragile. Lipids with unsaturated fatty acids are subject to oxidative degradation, and both saturated and unsaturated lipids can hydrolyze into lysolipids and free fatty acids1. For that reason, FDA guidance asks for stability testing of liposomal drugs that tracks vesicle size distribution and integrity, along with the chemical stability of the lipids and the encapsulated ingredient1. It also asks for stress testing of each lipid against heat, cold, light, pH and oxygen1.
Key takeaways
- A liposome is one or more phospholipid bilayers around a water core; water-soluble ingredients sit inside and fat-soluble ones in the membrane.
- Liposomal drugs are characterized for vesicle size, encapsulated versus free drug and lipid breakdown, and those numbers are what define a real liposome.
- Stomach acid, bile salts and pancreatic lipases damage conventional liposomes, and intact uptake through M cells is limited.
- Liposomal vitamin C raised blood levels in 9 of 10 small, industry-linked studies, with no clear added biological effect shown so far.
- The main liposomal glutathione study was a 12-person pilot without a non-liposomal comparison group.
References
- Liposome Drug Products: Chemistry, Manufacturing, and Controls; Human Pharmacokinetics and Bioavailability; and Labeling Documentation. Guidance for Industry
- Liposome: classification, preparation, and applications
- Liposomal Formulations in Clinical Use: An Updated Review
- Adapting liposomes for oral drug delivery
- Do Liposomal Vitamin C Formulations Have Improved Bioavailability? A Scoping Review Identifying Future Research Directions
- Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function
- Liposomal-encapsulated Ascorbic Acid: Influence on Vitamin C Bioavailability and Capacity to Protect Against Ischemia-Reperfusion Injury
Frequently asked questions
How big is a liposome?
Liposomes range from about 30 nanometers to several micrometers across2. Vesicles in liposomal vitamin C products studied in humans ranged from about 20 nanometers to more than 1 micrometer5. Size matters because, together with the number of bilayers, it affects how much of an ingredient a liposome can hold2.
Are liposomes used in approved medicines?
Yes. Liposomal doxorubicin was introduced in the US in 1995 as the first FDA-approved nano drug delivery system based on PEGylated liposomes3. Liposomal formulations of the antifungal amphotericin B followed in 1996 and 19973. These are intravenous drugs reviewed through drug applications, the category FDA's liposome guidance addresses1,3.