Revoderm

Multi-Vitamin Moisturizer

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).

First, it's really stable and easy to formulate, so the problems that come with pure vitamin C are solved here.

Second, in vitro (meaning made in the lab, not on real humans) studies show that ascorbyl glucoside can penetrate the skin. This is kind of important for an anti-aging ingredient to do the job, so this is good news, though in-vivo (made on real humans) studies are still needed. 

Third, in-vitro studies show that after ascorbyl glucoside is absorbed into the skin it is converted to pure vitamin C (though the rate of conversion is still a question mark). It also shows all the three anti-aging benefits (antioxidant protection + collagen boosting + fading hyperpigmentation) that pure vitamin C does. 

Bottom line: ascorbyl glucoside is one of the best and most promising vitamin C derivatives that shows similar benefits to that of pure vitamin C, but it's less proven (in vivo vs. in vitro studies) and the extent of the benefits are also not the same.  

MAP does solve the stability problem: it's stable up to pH 7, so far so good. What is not so good is that, as the great review study about vitamin C derivatives in the Journal of Cosmetic Dermatology writes, MAP is "at very best, poorly absorbed in comparison to AA." 

Moreover,  derivatives not only have to be absorbed into the skin, they also have to be converted into pure AA. The good news is that in-vitro data shows that MAP does convert, but the bad news is we do not really know if the same is true on real, living human skin. Even if it does, we don't know how good the conversion rate is (but to be fair the same is true for all other derivatives).

Regarding the three magic abilities of pure vitamin C (antioxidant, collagen booster, skin brightener), there is no published data about MAP's antioxidant or photoprotection capabilities. We have better news about the other two things: in-vitro data shows that MAP can boost collagen synthesis similar to AA (though in the case of AA it's proven in-vivo) and even better, MAP is proven to work as a skin brightener in-vivo (on real people). 

Bottom line: when it comes to vitamin C derivatives, MAP is definitely an option. We especially recommend it if you are after skin brightening as this seems to be the strongest point of MAP. 

SAP (the vit C derivative, not the enterprise software, obvs) is a promising derivative that has great stability up to pH 7. The challenge with it though is skin penetration. Unfortunately, it seems to be limited, or to quote a great article from the Journal of Cosmetic Dermatology "topically applied ascorbyl phosphate salts are, at very best, poorly absorbed in comparison with AA". Regarding conversion to AA, there seems to be no data about it, so we can neither deny nor confirm it.

We have better news regarding the three magic abilities of vitamin C: there is in-vivo (tested on real people) data showing that SAP does have photo-protective (aka antioxidant) properties, though less than pure AA. SAP might also aid collagen boosting; in-vitro (made in the lab) data shows that it works, but is less effective than another vitamin C derivative, called MAP (that seems to be as effective as pure AA). As for skin-brightening, there is a trade publication with in-vivo data showing that SAP can fade brown spots. 

Another thing SAP might be able to do is to help with acne. A 2005 study showed in vitro (in test tubes) that 1% SAP has a strong antimicrobial activity on evil acne causing P. acnes and it also showed in vivo (on real people) that 5% SAP can strongly improve the inflammatory and non-inflammatory lesions of acne vulgaris. In fact, the results were comparable or even slightly better than with 5% benzoyl peroxide. 

And there is even more regarding SAP and acne. A nice double-blind study from 2009 showed that  5% SAP reduced the inflammatory lesions by 20.14% and 48.82% within 4 and 8 weeks respectively and when combined with 0.2% retinol the results were even better. With this combination treatment, the improvement was 29.28% after 4 weeks and 63.10% after 8 weeks of application. 

Aside from research studies, anecdotal evidence also supports SAP being a promising vitamin C derivative. One of the best-selling (vitamin C) serums in Sephora is the Ole Henriksen Truth Serum, while on Amazon it's the OzNaturals Vitamin C 20 Serum. Another popular choice is the Mad Hippie Vitamin C serum, and all of these contain vitamin C in the form of SAP. 

Overall, we think SAP is a goody!  In terms of anti-aging, it's probably not as effective as pure Ascorbic Acid, but it's totally worth a try. However, if your skin is acne-prone, SAP is your form of Vitamin C and it's a must-try.

As for hair care, it is a non-volatile silicone meaning that it stays on the hair rather than evaporates from it and smoothes the hair like no other thing. Depending on your hair type, it can be a bit difficult to wash out and might cause some build-up (btw, this is not true to all silicones, only the non-volatile types). 

What's the problem?

Firstly, it's stability is only similar to that of pure ascorbic acid (AA), which means it is not really stable. A great study in the Journal of Cosmetic Dermatology compared a bunch of vitamin C derivatives and this derivative was the only one where the study said in terms of stability that it's "similar to AA". Not really that good.

Second, a study that examined the skin absorption of vitamin C found that ascorbyl palmitate did not increase the skin levels of AA. This does not mean that ascorbyl palmitate cannot penetrate the skin (because it can, it's oil soluble and the skin likes to absorb oil soluble things) but this means that it's questionable if ascorbyl palmitate can be converted into pure Vit C in the skin. Even if it can be converted, the palmitate part of the molecule is more than the half of it, so the efficacy will not be good and we have never seen a serum that contains a decent (and proudly disclosed) amount of AP.  We are highly skeptical what effect a tiny amount of AP has in a formula.

Third, another study that wanted to examine the antioxidant properties of AP was surprised to find that even though AP does have nice antioxidant properties; following UVB radiation (the same one that comes from the sun) it also promotes lipid peroxidation and cytotoxicity. It was only an in-vitro study meaning that it was done on cell cultures and not on real people, but still, this also does not support the use of AP too much. 

The only good thing we can write about Ascorbyl Palmitate is that there is an in-vitro (made in the lab, not on real people) study showing that it might be able to boost collagen production.

Regarding the skin-brightening properties of pure vitamin C, this is another magic property AP does not have, or at least there is no data, not even in-vitro, about it.

Overall, Ascorbyl Palmitate is our least favorite vitamin C derivative. It is there in lots of products in tiny amounts (honestly, we do not really understand why), however, we do not know about any vitamin C serum featuring AP in high amounts. That is probably no coincidence. If you are into vitamin C, you can take a look at more promising derivatives here. 

A very common scenario is that  Citrus Aurantium Dulcis Fruit Extract is on the ingredient list for its mild, natural exfoliant properties. It contains mainly citric acid and some malic acid, AHA exfoliants known for their skin renewing properties. If that's the case, it is usually combined with other AHA containing fruits such as bilberry, sugar cane, lemon, and sugar maple in a super popular ingredient mix trade named ACB Fruit Mix.

But orange fruit is loaded with lots of other active compounds with a wide variety of possible effects. A well-known one is the antioxidant vitamin C, aka ascorbic acid, but the dosage will vary based on the extraction method, and it’s possible that some of the ascorbic acid content will degrade before extraction process even takes place. If you want vitamin C in your skincare, that is smart, but do not rely on orange fruit extract for it.

Flavonoids (hesperidin, naringin, luteolin, and ferulic acid) are also nice active compounds with possible antioxidant, anti-inflammatory, and vasoprotective effects. Some of them (namely hesperidin and luteolin) might even have skin brightening activity by inhibiting tyrosinase, the famous enzyme needed for melanin production.

The orange extract also contains carbohydrates, aka sugars (mostly glucose, fructose, and sucrose, but also some bigger polysaccharides such as pectin) giving the ingredient some moisturizing properties.

Some essential oil content is usually also present in citrus fruit extracts, which means a nice scent and antibacterial properties, but also some questionable compounds such as fragrance allergen limonene or phototoxic compound bergaptene. If the amount is big enough to worry about is questionable, probably not, however, the same question applies to all the nice beneficial compounds. 

Overall, we think that the orange fruit extract is a very complex ingredient with lots of potentially good things in it, but we could not find proper in-vivo (made on real people) studies made with standardized extracts to validate what it really does or does not under real-world use cases. 

Other than having a good safety profile and being quite gentle to the skin it has some other advantages too. It can be used in many types of formulations as it has great thermal stability (can be heated up to 85°C) and works on a wide range of pH levels (ph 3-10). 

It’s often used together with ethylhexylglycerin as it nicely improves the preservative activity of phenoxyethanol.

Anyway, it doesn't matter if it reflects or absorbs, Titanium Dioxide is a pretty awesome sunscreen agent for two main reasons: it gives a nice broad spectrum coverage and it's highly stable. Its protection is very good between 290 - 350 nm (UVB and UVA II range), and less good at 350-400 nm (UVA I) range. Regular sized Titanium Dioxide also has a great safety profile, it's non-irritating and is pretty much free from any health concerns (like estrogenic effect worries with some chemical filters).

The disadvantage of Titanium Dioxide is that it's not cosmetically elegant, meaning it's a white, "unspreadable" mess. Sunscreens containing Titanium Dioxide are often hard to spread on the skin and they leave a disturbing whitish tint. The cosmetic industry is, of course, really trying to solve this problem and the best solution so far is using nanoparticles. The itsy-bitsy Nano-sized particles improve both spreadability and reduce the whitish tint a lot, but unfortunately, it also introduces new health concerns. 

The main concern with nanoparticles is that they are so tiny that they are absorbed into the skin more than we want them (ideally sunscreen should remain on the surface of the skin). Once absorbed they might form unwanted complexes with proteins and they might promote the formation of evil free radicals. But do not panic, these are concerns under investigation. A 2009 review article about the safety of nanoparticles summarizes this, "to date, in-vivo and in-vitro studies have not demonstrated percutaneous penetration of nanosized particles in titanium dioxide and zinc oxide sunscreens". The English translation is, so far it looks like sunscreens with nanoparticles do stay on the surface of the skin where they should be.  

All in all, Titanium Dioxide is a famous sunscreen agent and for good reason, it gives broad spectrum UV protection (best at UVB and UVA II), it's highly stable, and it has a good safety profile. It's definitely one of the best UV-filter agents we have today, especially in the US where new-generation Tinosorb filters are not (yet) approved. 

As for cosmetics, the CIR (Cosmetic Ingredient Review) concluded that the amount of BHT used in cosmetic products is low (usually around 0.01-0.1%),  it does not penetrate skin far enough to be absorbed into the bloodstream and it is safe to use in cosmetics.

What is true is that if a product contains so-called N-nitrogenating agents (e.g.: preservatives like 2-Bromo-2-Nitropropane-1,3-Diol, 5-Bromo-5-Nitro- 1,3-Dioxane or sodium nitrate - so look out for things with nitro, nitra in the name) that together with TEA can form some not nice carcinogenic stuff (that is called nitrosamines). But with proper formulation that does not happen, TEA in itself is not a bad guy. 

But let’s assume a bad combination of ingredients were used and the nitrosamines formed. :( Even in that case you are probably fine because as far as we know it cannot penetrate the skin. 

But to be on the safe side, if you see Triethanolamine in an INCI and also something with nitra, nitro in the name of it just skip the product, that cannot hurt.