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In this article
At a glance
- ‘Best absorbed’ is a comparison, and it’s only as reliable as the study behind it. The questions to ask: what was measured, compared with what, and at what amount?
- For liposomal vitamin C, comparisons like this do exist: in most studies, blood levels were higher than with standard vitamin C.
- Taking more doesn’t mean absorbing proportionally more. With vitamin C and vitamin B12, the share absorbed falls as the single dose rises.
- Our verdict: as a blanket promise, it can’t be checked. For individual nutrients and forms, though, there are good measurements.
What the promise actually claims
Whether it’s vitamin C, vitamin B12 or glutathione, many people look for the form their body absorbs best, and plenty of packs promise exactly that. ‘Best absorbed’ sounds like a measurement, but it’s really a comparison. Best compared with which form? At what amount? And measured how?
Experts call this bioavailability: the share of a nutrient that reaches the blood after you take it and is then available to the body. Our article Bioavailability: why the dose alone isn’t enough explains why the amount on the label tells you little about this.
How is absorption measured?
In a typical study, healthy adults take a single dose, and blood samples are then taken repeatedly over several hours. In one vitamin C study, this was done at eleven time points, from the moment of intake to 24 hours later1. Two key figures come from these values: the peak level and the area under the curve, which reflects the amount in the blood over the whole period.
These figures only mean something in a direct comparison. Good studies give the same people the same amount in two forms, one after the other, without the participants knowing which one they’re taking. Because the amount and the people stay the same, a crossover study like this shows whether the form makes a difference1.
Vitamin C: where real comparisons exist
A review found ten studies in humans comparing liposomal with standard vitamin C. In nine of them, the liposomal form had higher bioavailability: the peak level was 1.2 to 5.4 times as high, and the area under the curve 1.3 to 7.2 times as high2. However, the studies used very different formulations and amounts2.
In the study with eleven time points, 27 healthy adults each took 500 mg of vitamin C. With the liposomal form, the peak level in blood plasma was 27% higher, and 21% higher calculated over 24 hours1. How liposomal, buffered and pure vitamin C differ is covered in our article Vitamin C: liposomal, buffered or ascorbic acid?
Does a bigger dose mean more is absorbed?
Not necessarily. In a study with seven healthy volunteers, the body fully absorbed a single dose of 200 mg of vitamin C. From single doses of 500 mg, the share absorbed fell, and the body excreted the absorbed vitamin C in the urine3.
Vitamin B12 behaves in a similar way. The gut absorbs small amounts through its own transport route, while with large amounts only a small part reaches the blood by simple (passive) diffusion4. A model calculation put the share absorbed at 83% for 1 µg and 1% for 1,000 µg4. So the share falls, but the amount absorbed still rises, because 1% of 1,000 µg is more than 83% of 1 µg. That’s why the number on the label doesn’t tell you, on its own, how much reaches the blood.
200 mg
of vitamin C as a single dose was fully absorbed in a small study3
9 out of 10
comparison studies measured higher bioavailability with liposomal vitamin C2
How to recognise a reliable claim
If a product promises to be best absorbed, four questions help:
- Is there a study in humans, or only laboratory tests?
- Was it compared with another form at the same amount?
- How many people took part, and for how long were measurements taken?
- Who paid for the study?
How to assess studies on food supplements is explained in our article Understanding the evidence: how to read supplement studies.
Good to know Even good comparison studies have their limits. All the vitamin C studies in the review were industry-funded or had authors working for companies2. They measure blood levels after a single dose and say nothing about how you feel.
‘Best absorbed’? Our verdict: not as a blanket statement
As a general statement without a study behind it, ‘best absorbed’ can’t be checked. For individual nutrients and forms, though, there are reliable comparisons, for example for liposomal vitamin C2. So don’t just ask whether something is well absorbed. Ask, too: compared with what?
The comparison studies on liposomal vitamin C were carried out with other manufacturers’ formulations. At Melinava, we use phospholipids from European sunflowers for our liposomal products.
Frequently asked questions about vitamin absorption
Which vitamin C is absorbed best?
In nine out of ten comparison studies, bioavailability was higher with liposomal vitamin C than with standard vitamin C2. The amount you take at once also matters: in a small study, a single dose of 200 mg was fully absorbed3. Do not exceed the recommended daily amount.
Which vitamin B12 is absorbed best?
With vitamin B12, the share that reaches the blood depends heavily on the amount taken at once. The gut absorbs small amounts through its own transport route, and with large amounts, simple diffusion comes into play as well4. The different forms are covered in our article Which vitamin B12?
Which glutathione is absorbed best?
We found no studies in humans directly comparing liposomal glutathione with other forms. In a small study with 12 healthy adults, whole-blood glutathione rose by up to 40% after two weeks on a liposomal form; the study was funded by a manufacturer5. There’s more in our article Glutathione: liposomal, reduced or S-acetyl?
Sources
- Purpura M, Jäger R, Godavarthi A, Bhaskarachar D, Tinsley GM (2024). Liposomal delivery enhances absorption of vitamin C into plasma and leukocytes: a double-blind, placebo-controlled, randomized trial. European Journal of Nutrition 63(8):3037-3046. DOI
- Carr AC (2025). Do Liposomal Vitamin C Formulations Have Improved Bioavailability? A Scoping Review Identifying Future Research Directions. Basic & Clinical Pharmacology & Toxicology 137(1):e70067. DOI
- Levine M, Conry-Cantilena C, Wang Y, et al. (1996). Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance. Proceedings of the National Academy of Sciences 93(8):3704-3709. DOI
- Zhang M, Almond LM, Jones HM (2025). Physiologically Based Pharmacokinetic Modeling of Vitamin B-12 Incorporating Mechanistic Absorption: An Example Application for Intake Estimation During Pregnancy. The Journal of Nutrition 155(10):3220-3228. DOI
- Sinha R, Sinha I, Calcagnotto A, et al. (2018). Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function. European Journal of Clinical Nutrition 72(1):105-111. DOI
This article is for general information only and should not replace medical advice. Food supplements are not a substitute for a balanced and varied diet and a healthy lifestyle.
Written by
Melinava Editorial Team