The Sugar That Keeps Tardigrades Alive Is in Your Moisturiser

The tardigrade story is out of date

Every piece of marketing copy about ↗trehalose opens the same way: this is the sugar that lets tardigrades dry out completely and come back to life years later. It is a genuinely great story, it is why the ingredient gets attention, and it has been wrong — or at least badly incomplete — since 2017.

That year, a paper in Molecular Cell reported something inconvenient: trehalose, a disaccharide essential for several organisms to survive drying, is detected at low levels or not at all in some tardigrade species. The researchers identified a different mechanism entirely — tardigrade-specific intrinsically disordered proteins, which are constitutively expressed at high levels or induced during desiccation, are required for tardigrade desiccation tolerance, and are sufficient to increase desiccation tolerance when expressed in other organisms. Those proteins form non-crystalline amorphous solids on drying.

So the tardigrade's headline trick is a protein, not a sugar.

This does not demote trehalose. It is still the anhydrobiosis molecule for brine shrimp, nematodes, baker's yeast and resurrection plants — an entirely respectable biography for any ingredient, and one with more direct experimental support than the tardigrade version ever had. But when a product's story rests on the water bear specifically, the story is a decade behind the literature, and that is a useful thing to notice about how ingredient marketing gets written: from a memorable anecdote rather than from the current papers.

Anhydrobiosis, and what vitrification actually means

The underlying phenomenon is real and remarkable regardless of which molecule does it. Anhydrobiosis is life without water — organisms that lose essentially all their cellular water, enter a state with no measurable metabolism, persist for years, and resume on rewetting. Antonie van Leeuwenhoek watched dried rotifers come back to life more than three hundred years ago, and the mechanism remained genuinely mysterious for most of the intervening period.

Water is not incidental to a cell. Membranes hold their spacing partly because water hydrogen-bonds to the phospholipid head groups; proteins fold correctly partly because water shapes what is energetically favourable. Take the water away and membranes undergo phase transitions and fuse, and proteins denature. Rehydration then does not restore the arrangement — it just adds water to wreckage.

Trehalose is proposed to prevent that through two mechanisms, which are not mutually exclusive.

Water replacement. The molecule hydrogen-bonds directly to the phospholipid head groups, occupying the positions water has vacated. Membrane spacing is preserved, the phase transition is suppressed, and the structure survives the drying.

Vitrification. Trehalose forms a non-crystalline amorphous glass — not a crystal, which would be sharp and destructive, but a rigid, immobile, structureless solid. Everything embedded in it stops moving, and reactions that require molecular mobility effectively cease. The cell is not protected chemically so much as paused.

The elegance of the 2017 finding is that the tardigrade proteins were shown to vitrify too, and that their protective capacity mirrored their vitrified state. Different molecule, same physical trick — which suggests the glass is the point, and the identity of what forms it is a matter of what a lineage happened to evolve.

Against glycerin, on the actual properties

Here is where the honest comparison has to happen, because 'better humectant' is the claim most often attached to trehalose and it is not well supported.

**↗Glycerin** is a small three-carbon trihydric alcohol. It is intensely hygroscopic, it has decades of human data behind it, it is inexpensive, and it is the reference standard against which every other humectant is measured. It is also, unglamorously, very hard to beat.

Trehalose is a disaccharide — two glucose units, so a substantially larger molecule. Gram for gram it is less hygroscopic than glycerin, which means that on the single axis of pulling water out of the air and holding it, it does not win.

What it has instead is chemistry. Trehalose is a non-reducing sugar: its two glucose units are joined through both of their anomeric carbons, leaving no free reducing group. That single structural fact produces most of its practical virtues. It is exceptionally chemically stable. It resists hydrolysis across a wide pH range. And it does not participate in Maillard-type reactions the way reducing sugars do — which is the basis of the anti-glycation hypothesis attached to it, and also the reason it is used as a stabiliser for other ingredients rather than only as a humectant in its own right.

So the accurate framing is not 'trehalose is a better glycerin'. It is: trehalose is a differently-behaved humectant with a stability story attached — one that formulators value for reasons that have as much to do with the rest of the formula as with your skin. The ↗humectant category is not a ladder with a winner at the top; it is a set of molecules with different sizes, different water affinities and different chemical behaviours, and good formulas use several.

How far the human data actually goes

This is the part that determines whether any of the above matters on a face, and it deserves to be answered rather than sidestepped.

The desiccation biology is excellent, and it is about cells losing essentially all of their water — a state so extreme that metabolism stops. Your stratum corneum, even when it feels unbearably dry and tight, is nowhere near that condition. So the transfer question is genuinely open: does membrane stabilisation at near-zero residual water tell you anything useful about skin at ordinary hydration levels? The mechanism is real in its own domain. Nobody has demonstrated that the domain includes your cheek.

What exists specifically on skin is thin and should be described precisely. A 2025 study using human skin explants tested a product combining ↗hyaluronic acid at several molecular weights with trehalose against glycation stress, and reported a 45% reduction in carboxymethyllysine formation — a well-established glycation marker — at baseline, and a 30% reduction under methylglyoxal-induced stress, while preserving cell viability.

That is an interesting result. It is also, stated fairly: skin explants, not living people; an injectable product, not a topical; a combination, so trehalose cannot be isolated from the hyaluronic acid; and published with declared consultancy relationships between authors and the manufacturer. Every one of those is normal in early cosmetic science and every one of them limits what can be concluded. It is a reasonable signal that the anti-glycation hypothesis is worth pursuing. It is not evidence that a trehalose-containing cream does anything measurable to glycation in your skin.

The honest overall verdict, then: trehalose is a competent, stable, well-tolerated humectant with an unusually good origin story and a mechanistic hypothesis that nobody has yet tested properly on human skin under realistic conditions. That is a respectable position for an ingredient. It is simply several steps short of what the water-bear framing implies.

Where it sits in a formula, and what that tells you

In practice, trehalose is used at modest levels, in the humectant phase, and almost always alongside glycerin and hyaluronic acid rather than instead of them — which is itself informative about how formulators regard it.

Clinique Moisture Surge 100H pairs it with hyaluronic acid and urea; Neutrogena Hydro Boost Hyaluronic Acid Serum with hyaluronic acid, glycerin and ↗panthenol; ROUND LAB 1025 Dokdo Sleeping Pack with panthenol and hyaluronic acid; and COSRX The Niacinamide 15 Serum uses it in a formula whose headline active is something else entirely. It also turns up in cleansers and sunscreens, where its stability rather than its humectancy is the reason it was chosen.

Which points at the practical rule. Position on the ingredient list is more informative than presence. A trehalose sitting in the humectant phase of a well-built moisturiser is doing a real, modest job as part of a system. A trehalose named on the front of a box that appears below the preservative on the back is decoration, and the ingredient decoder will tell you which one you are looking at in about twenty seconds.

It is worth putting next to its closest relative in this category. ↗Beta-glucan is another polysaccharide humectant, larger again, with its own soothing and film-forming behaviour and a somewhat better developed skin literature — you will find it doing that work in Cocokind Ceramide Barrier Serum and Rhode Glazing Mist. Neither is a replacement for the other, and a formula containing several humectants of different sizes is generally a better-designed formula than one leaning on a single fashionable molecule.

The rule that matters more than which sugar

Everything above is a discussion about which humectant, and humectants are the half of hydration that people over-think.

A humectant attracts and binds water. That is all it does. In a humid environment it pulls moisture from the air; in a dry one — a heated room in winter, a plane, an air-conditioned office — the water available to it comes substantially from deeper in your own skin, and if nothing is holding it there, it evaporates from the surface and you end up drier than when you started. This is why people report that a hyaluronic acid serum 'made my skin worse', and they are not imagining it.

So the rule: a humectant needs something over it. An occlusive or a decent emollient layer converts water attracted to the surface into water retained in the stratum corneum. Trehalose under an occlusive is doing its job. Trehalose applied alone to bare skin in a dry room is a physics problem wearing a marketing claim.

Which reduces the practical advice to something almost disappointingly plain. If a moisturiser contains trehalose alongside glycerin, a lipid component and something occlusive, that is a well-constructed humectant system and a perfectly good reason to like the product. If trehalose is the headline, the price reflects the headline, and the story on the box is about a tardigrade — you are paying for an anecdote that the tardigrade researchers themselves retired in 2017.