Trehalose, Explained: The Disaccharide That Lets Tardigrades Survive Drying Out (and What 0.5%-5% Does in a Moisturizer)
Trehalose reads like a marketing word, but it's the same sugar that lets a tardigrade dry to a husk for years and rehydrate unharmed -- and that trick is why it's in your moisturizer.
What Trehalose Actually Is
Trehalose is a non-reducing disaccharide -- two glucose units joined by a 1,1-glycosidic bond, sturdier than sucrose. It occurs in mushrooms, honey, and drying-surviving organisms like tardigrades. Its INCI name is simply "Trehalose."
The Water-Replacement Hypothesis
Those organisms flood their cells with trehalose before drying out. Biophysicists John and Lois Crowe (UC Davis) proposed its hydroxyl groups hydrogen-bond where water used to sit on proteins and membranes, keeping their shape -- why freeze-dried platelets and DNA survive better with it added.
Vitrification: The Other Half
A second idea: trehalose forms a glass-like matrix at low water content, immobilizing cell parts instead of substituting for water.
The Concentration in a Moisturizer
Cosmetic formulas typically use trehalose at 0.5%-5%. A 2024 emulsion study tested 1%, 2.5%, and 5%, measuring water loss and corneometer readings; the most-cited supplier data used 3%. Near the tail of a long ingredient list, it's likely under 1% -- stabilizer duty, not the named humectant.
The Strongest Evidence Is an Eye Drop
Thealoz Duo, an EU dry-eye product, pairs 3% trehalose with 0.15% sodium hyaluronate and improved tear-film break-up time in trials -- evidence it works at 3% on a bathed mucosal surface, not that a moisturizer at some undisclosed percentage repairs your barrier the same way.
What Trehalose Doesn't Do
It's a humectant and protectant, not a substitute for barrier lipids. It doesn't rebuild the ceramide-cholesterol-fatty acid matrix, and no trial shows it treating a skin condition. Persistent redness calls for a dermatologist, not another humectant.
What It Pairs With
It layers fine with other humectants -- hyaluronic acid, glycerin, panthenol -- much like polyglutamic acid layers with hyaluronic acid rather than replacing it. It won't buffer irritation from a nearby retinoid; it's a hydrator, not a fix for another ingredient's side effects.
Quick Recap
- A two-glucose disaccharide letting tardigrades survive near-total drying.
- Water-replacement and vitrification explain how it protects proteins as water leaves.
- Formulas typically use 0.5%-5%; cited hydration data used 3%.
- Its strongest evidence (3% eye drops) is ophthalmology, not skincare.
- A humectant/protectant, not a barrier-lipid replacement or irritation buffer.
Sources: Crowe & Crowe water-replacement research; tardigrade vitrification studies; 2024 emulsion TEWL study; trials on 3% trehalose eye drops. Not medical advice. Patch-test any new product, and see a dermatologist about persistent irritation.
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