Obagi

Retivance Skin Rejuvenating Complex

Once inside the skin, it hydrates, but not from the outside - putting pure water on the skin (hello long baths!) is drying. 

One more thing: the water used in cosmetics is purified and deionized (it means that almost all of the mineral ions inside it is removed). Like this, the products can stay more stable over time. 

As for skincare, argan oil is loaded with lots of skin goodies (but so are many other plant oils): it contains 80% nourishing and moisturizing unsaturated fatty acids, mainly oleic (38-50%), linoleic (28-38%) and palmitic (10-18%). It also contains a relatively large amount of antioxidant vitamin E (600-900 mg/kg, about twice as much as olive), small amounts of antioxidant phenols (including caffeic acid, ferulic acid, and epicatechin), as well as some rare sterols with soothing and anti-inflammatory properties. 

Thanks to all the above goodness in argan oil, it can greatly nourish and moisturize the skin and hair. It's also claimed to be able to neutralize collagen-damaging free radicals, help reduce scars, and revitalize and improve skin elasticity. You can even read that argan might help acne-prone skin, but being a high oleic oil, we would be careful with that. 

All in all, argan oil is a real goodie but we do not fully understand the special miracle status it enjoys.

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).

Once retinal is converted, it becomes retinoic acid and does the same things we detailed in our tretinoin description. In a nutshell, it is everything you expect from an anti-aging superstar such as decreased wrinkles, smoother, firmer and more elastic skin. 

This sounds good, but how does Retinal compare to retinoic acid? Good question! We found a study (a pretty good one with 125 patients) that compared 0.05% retinal with 0.05% retinoic acid (and vehicle).  They concluded that "at week 18, a significant reduction of the wrinkle and roughness features was observed with both retinaldehyde and retinoic acid." and the difference between the two was not statistically significant. (Interestingly, in both groups, the results were less significant at week 44, so it might be a good idea to have a retinoid break from time to time?) Also, our guy, Retinal was much better tolerated than retinoic acid known for its harshness. 

The good tolerability of retinal was also confirmed by another study that compared retinol (ROL), retinal (RAL) and retinoic acid (RA). They found that "the natural retinoids ROL and RAL do have a good tolerance profile, in contrast with the irritating potential of RA", meaning retinal is an awesome alternative if you have irritation and flaking issues with prescription products, such as Retin-A. 

Last, but not least, we want to mention a pretty big (but subjectively evaluated), Avene (the French pharmacy brand famous for its Retinal products) sponsored study that examined the tolerability and efficacy of a 0.1 Retinal + 6% glycolic acid product in the treatment of acne. The product was added next to the standard anti-acne regimen of 1,709 patients for 90 days and the study concluded that the formula was both very well tolerated as well as effective next to other standard anti-acne medications such as benzoyl peroxide and antibiotics.

Overall, if you are into retinoids, Retinal is a really awesome and well-proven member of the family that is absolutely worth trying. 

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. 

Though chamomile is usually a goodie for the skin, it's also not uncommon to have an allergic reaction to it.