Hydration: hyaluronic acid, Tremella, and what we are actually doing

CHAPTER FIVE  ·  THE RESILIENCE GUIDE

Hydration

Hyaluronic acid, Tremella, and the question of what we are actually doing.

By Barbi  ·  8 min read  ·  Founder, PHILOGENI

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Why is hyaluronic acid not enough?

There is a crack in everything. That's how the light gets in.

— Leonard Cohen, Anthem

Hyaluronic acid is one of those substances. It can be fantastic. It can also be entirely beside the point. It is time to crack this subject open and let some light in.

When I first started reformulating my routine for the skin I have now, I assumed — because every brand on the shelf had told me — that the answer to dryness was hyaluronic acid. I bought every serum on the high street. I layered them. I added more. My skin got drier. Not by a lot. Just enough that I should have noticed. I didn't, because I had been told for fifteen years that hyaluronic acid was the answer to dryness.

It was while I was studying for my Diploma in Natural Cosmetic Formulation with Formula Botanica that the picture began to clarify. The more I researched, the more I understood the extent to which hyaluronic acid has been added to products for the sake of marketing rather than functionality. It is now in shampoo. It is in toothpaste. It is in mascara. And most of the time, the molecular weight used is too large for the molecule to do anything meaningful for the skin at all.

What hyaluronic acid does for our skin — and, crucially, what it does not do — depends entirely on the molecular weight of the substance used, the humidity of the environment in which we are using it, and the formulation it is delivered alongside. The rest of this chapter walks through each of those variables, and ends with the botanical alternative the mushroom kingdom has been quietly offering us for a thousand years.

What hyaluronic acid actually is, and what it does

Hyaluronic acid is a polysaccharide — a long chain of sugar molecules — that occurs naturally in your skin, where it is produced by the dermal fibroblasts under estrogen signalling. Its remarkable property is that it holds water. A single hyaluronic acid molecule can hold up to a thousand times its own weight in water. In a young, well-functioning skin, hyaluronic acid is one of the main reasons the deeper layers stay plump, hydrated, and resilient.

As estrogen recedes in the hormonal transition, fibroblast production of hyaluronic acid declines. The skin holds less water in its deeper layers. The decline is documented in the literature — dermal hyaluronic acid drops measurably from the early forties onward. 1 This is why topical hyaluronic acid was, in principle, such an attractive idea: replace topically what the skin is making less of internally.

In practice, the replacement is only as useful as the molecule's ability to reach the layer where the body's own hyaluronic acid lives. This is where the chemistry stops being simple.

The three molecular weights

Hyaluronic acid in skincare comes in three rough size bands.

High molecular weight — above approximately one million Daltons — is the most common form on the high street. It sits on the surface of the skin and does not penetrate. It can pull water from the air to the surface and hold it there for a few hours, which feels like hydration. It does not reach the deeper layers where the body's own hyaluronic acid is depleting.

Medium molecular weight — roughly one hundred thousand to five hundred thousand Daltons — penetrates a little further into the stratum corneum but rarely reaches the dermis.

Low molecular weight, sometimes called fragmented or hydrolysed hyaluronic acid, below fifty thousand Daltons, penetrates deepest. It can also be pro-inflammatory if oversized fragments accumulate in the live epidermis. This is a real risk in poorly-formulated low-MW serums and is the reason a careful formulator does not simply use the smallest molecule available.

Most products that promise "hyaluronic acid" disclose only that the molecule is present. They rarely disclose the molecular weight. Without that information, the consumer is shopping blind. A well-formulated product layers two or three molecular weights together — sometimes called multi-weight or layered hyaluronic acid — to address different depths simultaneously. These are a minority of products on the market.

The low-humidity paradox

Hyaluronic acid is what chemists call a humectant — a substance that pulls water toward itself. In a humid environment, hyaluronic acid sitting on the skin pulls water from the air toward the surface, where the skin can use it. This is the intended use case.

In a low-humidity environment, the situation reverses. Most North American homes in autumn and winter are low-humidity. Airplane cabins are low-humidity. Air-conditioned offices are low-humidity. Skiing weeks are low-humidity. In any of these environments, there is not enough water in the air for the humectant to pull. The molecule still pulls water — that is its chemistry — but with no water available externally, it pulls from the deeper layers of your own skin to the surface. The deeper layers dehydrate faster. The skin feels drier rather than more hydrated.

Many women on long flights or in winter have applied a hyaluronic acid serum, watched their skin tighten over the next two hours, and assumed they had not used enough. They had used too much, in the wrong environment, with no lipid layer above it to seal the moisture in.

The lipid layer matters more than is commonly understood. Hyaluronic acid alone, applied to a barrier that is already depleted of its own lipids, can accelerate dehydration. Hyaluronic acid layered beneath a lipid-rich moisturiser or oil that seals the water in is a meaningfully different proposition. The chemistry of "I bought HA serum and my skin got drier" is almost always the chemistry of HA without a lipid seal above it.

Tremella — what the mushroom kingdom has been offering quietly for centuries

In traditional Chinese medicine, Tremella fuciformis — the silver ear mushroom, also called the snow mushroom — has been used as a skincare ingredient for over a thousand years. The Tang dynasty cosmetic records describe it as a substance for retaining moisture in the skin. Modern cosmetic chemistry has now characterised why.

Tremella polysaccharides are structurally similar to hyaluronic acid: long chains of sugar units with substantial water-binding capacity. Their average molecular size is smaller than that of high-molecular-weight hyaluronic acid, 2 which means the molecule penetrates the stratum corneum more efficiently. Their water-binding capacity is comparable to hyaluronic acid in laboratory measurements; some studies suggest a slight advantage, others a parity. The honest answer is that they are equivalent on hydration alone.

What is not in dispute is that Tremella brings an additional capacity that hyaluronic acid does not. The polysaccharide carries bioactive signalling — antioxidant, immunomodulatory, and barrier-supportive — in the same family of activities as the medicinal mushrooms discussed in Chapter 4. 3 Tremella is hydration plus signalling. Hyaluronic acid is hydration alone.

There is one more difference, and it matters at this stage of life. Hyaluronic acid in skincare is almost always produced by industrial bacterial fermentation — a clean and well-controlled process, but an industrial one. Tremella is cultivated by traditional growers, on logs, in a process closer to mushroom farming than to laboratory production. The supply chain is shorter and more transparent. The molecule is plant-derived. For women who care about the provenance of what they put on their skin, the distinction is real.

What to look for on a label

If hyaluronic acid is on the ingredient list, ask: is the molecular weight disclosed? If not, assume the most common high-molecular-weight form, and assume it will hydrate the surface but not the dermis. Look for a lipid component nearby — squalane, ceramides, or a botanical oil — that can serve as a seal above the humectant. The lipid is what makes the hyaluronic acid work.

If you see Tremella fuciformis polysaccharide on a label — sometimes listed as Tremella fuciformis sporocarp extract — you are looking at the substance most of the hyaluronic acid industry is reaching synthetic versions of. It is the more elegant ingredient. A small number of natural cosmetic brands have been switching to it in the last five years; almost no large brands have.

Hyaluronic acid is a humectant. Tremella is a humectant that also signals. In a hormonally-changed skin that needs more than hydration, the difference matters.

Sources cited in this chapter

1. Papakonstantinou E, Roth M, Karakiulakis G. Hyaluronic acid: A key molecule in skin aging. Dermato-Endocrinology. 2012;4(3):253-258.

2. Wen L, Gao Q, Ma CW, et al. Structure characterisation of polysaccharide from Tremella fuciformis Berk. Carbohydrate Polymers. 2016;142:198-205.

3. Ma X, Yang M, He Y, Zhai C, Li C. A review on the production, structure, bioactivities and applications of Tremella polysaccharides. International Journal of Biological Macromolecules. 2021;188:431-447.

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