Khadi

Retinol 2.5% Serum

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.

The complication, however, is that different extracts and distillates can be made from different parts of the plant (bark, twigs, and leaves are typically used) and different extraction methods from different parts produce different results. So if you see only Witch Hazel Extract or Witch Hazel Water on the ingredient list, it's a bit hard to know what you're actually getting but we will try to summarize the possibilities to give an idea.

The main biologically active components in Witch Hazel are hamamelitannin (a potent astringent and antioxidant), catechins (anti-inflammatory and antioxidant) and gallic acid (antibacterial). The bark extract contains by far the most hamamelitannin and it has the most gallic acid and catechins. The twigs contain fewer catechins, less gallic acid, and much less hamamelitannin (4.77% vs 0.18%). The leaves contain hardly any tannins (0.04%) or catechins and contain a medium amount of gallic acid (compared to the bark and twigs).

Witch Hazel also contains tiny amounts of the essential oil and fragrance component eugenol, but the amount is so small that it's probably not significant for the skin.

Apart from the differences in active components in different parts of the Witch Hazel bush, the extraction methods also vary. Witch Hazel Distillate contains 14% added alcohol according to the USP specifications  and alcohol is, at best drying, and at worst skin-damaging. Luckily, there are also alcohol-free distillates, so if you prefer no alcohol check the ingredient list carefully. Witch Hazel Extracts can also be made in different ways: browsing Ulprospector, we could find hydroglycolic, hydroalcoholic and glicerine/water based extracts.

Well-known skin care expert, Paula Begoun rates witch hazel as poor and says,  "depending on the form of witch hazel, you’re exposing your skin either to a sensitizing amount of alcohol or to tannins, or both." This might be the case if you are dealing with an alcoholic witch hazel bark water or extract, but looking at CosIng (the official INCI name listing of the EU), witch hazel bark water or witch hazel bark extract are not listed ingredients. Bark and leaf or bark and twig or all three are used together to create extracts, so the chance that there is too much hamamelitannin in the final cosmetic ingredient seems small. Also alcohol-free extracts and distillates exist; actually, the majority seem to be alcohol-free nowadays. So all in all, we think "Hamamelis Virginiana Extract" on the ingredient list is nothing to worry about.

We even found a German study that compared the efficacy of Hamamelis ointment to panthenol ointment for soothing the skin in children (from 27 days to 11 years old). They observed 309 children and concluded that both ointments were similarly effective but the one with Hamamelis was even better tolerated (98.2% vs. 92.3% tolerated well the ointments in the two groups).

All in all, Witch Hazel Extract is a sloppy INCI name (btw, not in the CosIng listing), and you do not really know what you're getting. Most probably though, you are getting a goody with nice astringent, soothing, antibacterial, and even antioxidant properties.

So what the heck is a wax ester and why is that important anyway? Well, to understand what a wax ester is, you first have to know that oils are chemically triglycerides: one glycerin + three fatty acids attached to it. The fatty acids attached to the glycerin vary and thus we have many kinds of oils, but they are all triglycerides. Mother Nature created triglycerides to be easily hydrolyzed (be broken down to a glycerin + 3 fatty acid molecules) and oxidized (the fatty acid is broken down into small parts) - this happens basically when we eat fats or oils and our body generates energy from it.

Mother Nature also created wax esters but for a totally different purpose. Chemically, a wax ester is a fatty acid + a fatty alcohol, one long molecule. Wax esters are on the outer surface of several plant leaves to give them environmental protection. 25-30% of human sebum is also wax esters to give us people environmental protection. 

So being a wax ester results in a couple of unique properties: First, jojoba oil is extremely stable. Like crazy stable. Even if you heat it to 370 C (698 F) for 96 hours, it does not budge. (Many plant oils tend to go off pretty quickly). If you have some pure jojoba oil at home, you should be fine using it for years. 

Second, jojoba oil is the most similar to human sebum (both being wax esters), and the two are completely miscible. Acne.org has this not fully proven theory that thanks to this, jojoba might be able to "trick" the skin into thinking it has already produced enough sebum, so it might have "skin balancing" properties for oily skin.

Third, jojoba oil moisturizes the skin through a unique dual action: on the one hand, it mixes with sebum and forms a thin, non-greasy, semi-occlusive layer; on the other hand, it absorbs into the skin through pores and hair follicles then diffuses into the intercellular spaces of the outer layer of the skin to make it soft and supple.

On balance, the point is this: in contrast to real plant oils, wax esters were designed by Mother Nature to stay on the surface and form a protective, moisturizing barrier and jojoba oil being a wax ester is uniquely excellent at doing that.

Regarding skincare and tea tree oil, its most well-known effect is probably being a well established anti-acne ingredient. Multiple studies confirm that TTO is effective against the evil acne-causing bacteria called P. acnes and the effectiveness of 5% TTO gel is comparable to the gold standard anti-acne treatment, 5% Benzoyl Peroxide lotion. You need to be a bit more patient with TTO, though, as its effects come slower but also with fewer side effects.

Regarding TTO and sensitive skin, we say that you should be careful. Even if your skin is not sensitive you should never put undiluted TTO on your skin. Luckily, it contains only very small amounts of the common allergens (such as limonene), but irritant and allergic reactions still happen, especially by oxidation products that occur in older or not properly stored oil.  So if you have some pure TTO at home, know that storage matters, keep it in a cool, dry, dark place and use it up in a reasonable amount of time.

Overall, we do not often give a goodie status to essential oils, but we feel that TTO's unique antibacterial and anti-acne properties with its minimal allergen content warrant an exception. If your skin is acne-prone, TTO is something to experiment with.

One of the biological activities of the centellosides is to be able to stimulate GAGs  (glycosaminoglycans - polysaccharides that are part of the liquidy stuff between our skin cells), and especially hyaluronic acid synthesis in our skin. This is probably one of the reasons why Centella Asiatica Extract has nice skin moisturizing properties that was confirmed by a 25 people, four weeks study along with Centella's anti-inflammatory effects.

Madecassoside can also help in burn wound healing through increasing antioxidant activity and enhancing collagen synthesis. Asiaticoside was shown to increase antioxidant levels on rats skin when applied at 0.2%. 

Centella Asiatica also often shows up in products that try to treat cellulite or striae. Of course, it cannot make a miracle but it might have some effect via regulating microcirculation and normalizing the metabolism in the cells of connective tissues. 

Bottom line: Gotu Kola is a great plant ingredient with proven wound healing, anti-inflammatory, and antioxidant properties. Nice to spot on any ingredient list.