Paula's Choice

Pore-reducing Toner

Ok, so now we know what ceramides are, let's see what they do in our skin: research shows clearly that they play a super important role in keeping the skin barrier healthy and the skin hydrated. If ceramides in the skin are decreased, more water can evaporate from the skin and there is less water remaining in the skin. So ceramides form kind of a "water-proof" protecting layer and make sure that our skin remains nice and hydrated. 

Now the question is only this: If we put ceramides all over our face do they work as well as ceramides already naturally in our skin? Well, the answer is probably a no, but they do work to some extent. The BeautyBrains blog made a fantastic article about ceramides and they have listed a couple of examples about studies showing that ceramides - especially when used in certain ratios with cholesterol and fatty acids  - do hydrate the skin and can help to repair the skin barrier.

So far we were writing about ceramides in plural. It's because there are lots of different ceramides, a 2014 article writes that currently 12 base classes of ceramides are known with over 340 specific species. Chemically speaking, ceramides are the connection of a fatty acid and a sphingoid base and both parts can have different variations that result in the different types of ceramides. 

Our current one, Ceramide 1, or more recently called Ceramide EOP, was the first one that was identified in 1982 and it's a special snowflake. It contains the essential fatty acid, linoleic acid and has a unique structure. It's believed that ceramide 1 plays a "binding role" in the lipid layers of the extracellular matrix. Along with ceramides 4 and 7, they also play a vital role in epidermal integrity and serve as the main storage areas for linoleic acid (a fatty acid that's also very important for barrier repair).  

Oh, and one more thing: alkaline pH inhibits enzymes that help ceramide synthesis in our skin. So if you use a soap and you notice your skin is becoming dry, now you know why. 

It's a really promising candidate (see below), but while reading all the goodness about it in a minute, do not forget that derivatives not only have to be absorbed into the skin but also have to be converted to pure vitamin C (ascorbic acid or AA) and the efficacy of the conversion is often unknown. In addition, vitamin C's three magic properties (antioxidant, collagen booster, skin brightener) are all properly proven in-vivo (on real people), but for the derivatives, it's mostly in-vitro studies or in the case of THDA, it's in-vitro and done by an ingredient supplier.

With this context in mind let's see what THDA might be able to do. First, it is stable (if pH < 5), easy to formulate, and a joy to work with for a cosmetic chemist.

Second, because it's oil-soluble, its skin penetration abilities seem to be great. So great in fact, that it surpasses the penetration of pure vitamin C threefold at the same concentration and it penetrates successfully into the deeper layers of the skin (that is usually important to do some anti-aging work). There is also in-vitro data showing that it converts to AA in the skin. 

Third, THDA seems to have all three magic abilities of pure vitamin C: it gives antioxidant protection from both UVB and UVA rays, it increases collagen synthesis (even more than AA) and it has a skin brightening effect by reducing melanogenesis by more than 80% in human melanoma cell cultures.

So this all sounds really great, but these are only in-vitro results at this point. We could find Tetrahexyldecyl Ascorbate mentioned only in one published in-vivo study that examined the anti-aging properties of a silicone formula containing 10% AA and 7% THDA. The authors theorized that the 10% AA is released slowly from the silicon delivery system and probably stays in the upper layer of the skin to give antioxidant benefits, while THDA penetrates more rapidly and deeply and gives some wrinkle-reducing benefits. The study was a small (10 patients), double-blind experiment, and the formula did show some measurable anti-aging results. However, it is hard to know how much pure vitamin C or THDA can be thanked.

Bottom line: a really promising, but not well-proven vitamin C derivative that can be worth a try especially if you like experimenting (but if you like the tried and true, pure vitamin C will be your best bet).

In spite of this, if you search for "hyaluronic acid vs sodium hyaluronate" you will find on multiple places that sodium hyaluronate is smaller and can penetrate the skin better. Chemically, this is definitely not true, as the two forms are almost the same, both are polymers and the subunits can be repeated in both forms as much as you like. (We also checked Prospector for sodium hyaluronate versions actually used in cosmetic products and found that the most common molecular weight was 1.5-1.8 million Da that absolutely counts as high molecular weight).

What seems to be a true difference, though, is that the salt form is more stable, easier to formulate and cheaper so it pops up more often on the ingredient lists. 

If you wanna become a real HA-and-the-skin expert you can read way more about the topic at hyaluronic acid (including penetration-questions, differences between high and low molecular weight versions and a bunch of references to scientific literature).

A 2007 study showed that Phytosphingosine even works against evil acne-causing bacteria, Propionibacterium acnes and shows promise as a complementing active ingredient in treating acne-prone skin thanks to its anti-inflammatory and antimicrobial activities.  

A nice one to spot in the ingredient list. :)

Another great thing about panthenol is that it has anti-inflammatory and skin protecting abilities. A study shows that it can reduce the irritation caused by less-nice other ingredients (e.g. fragrance, preservatives or chemical sunscreens) in the product.

Research also shows that it might be useful for wound healing as it promotes fibroblast (nice type of cells in our skin that produce skin-firming collagen) proliferation. 

If that wasn’t enough panthenol is also useful in nail and hair care products. A study shows that a nail treatment liquide with 2% panthenol could effectively get into the nail and significantly increase the hydration of it.

As for the hair the hydration effect is also true there. Panthenol might make your hair softer, more elastic and helps to comb your hair more easily.