Pure Vitamin C Serum 12.5%
Ingredients overview
Highlights
Key Ingredients
Skim through
RESH LAB Pure Vitamin C Serum 12.5%Ingredients explained
Good old water, aka H2O. The most common skincare ingredient of all. You can usually find it right in the very first spot of the ingredient list, meaning it’s the biggest thing out of all the stuff that makes up the product.
It’s mainly a solvent for ingredients that do not like to dissolve in oils but rather in water.
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.
- Works best between a concentration of 5-20%
- Boosts the skin’s own collagen production
- Fades pigmentation and brown spots
- If used under sunscreen it boosts its UV protection
- Extremely unstable and oxidizes very easily in presence of light or air
- Stable in solutions with water only if pH is less than 3.5 or in waterless formulations
- Vit E + C work in synergy and provide superb photoprotection
- Ferulic acid doubles the photoprotection effect of Vit C+E and helps to stabilize Vit C
- Potent Vit. C serums might cause a slight tingling on sensitive skin
Butylene glycol, or let’s just call it BG, is a multi-tasking colorless, syrupy liquid. It’s a great pick for creating a nice feeling product.
BG’s main job is usually to be a solvent for the other ingredients. Other tasks include helping the product to absorb faster and deeper into the skin (penetration enhancer), making the product spread nicely over the skin (slip agent), and attracting water (humectant) into the skin.
It’s an ingredient whose safety hasn’t been questioned so far by anyone (at least not that we know about). BG is approved by Ecocert and is also used enthusiastically in natural products. BTW, it’s also a food additive.
- A natural moisturizer that’s also in our skin
- A super common, safe, effective and cheap molecule used for more than 50 years
- Not only a simple moisturizer but knows much more: keeps the skin lipids between our skin cells in a healthy (liquid crystal) state, protects against irritation, helps to restore barrier
- Effective from as low as 3% with even more benefits for dry skin at higher concentrations up to 20-40%
- High-glycerin moisturizers are awesome for treating severely dry skin
A very stable and promising form of the skincare superstar, Vitamin C. If you do not know why Vitamin C is such a big deal in skin care, you can catch up here. In short, Vitamin C has three proven magic abilities: antioxidant, collagen booster, and skin brightener. The problem, though, is that it's very unstable, turns brown and becomes ineffective in no time (after a few month) and the cosmetics industry is trying to come up with smart derivatives that are stable and have the magic properties of pure Vitamin C.
Ethyl Ascorbic Acid or EAC for short is an "etherified derivative of ascorbic acid" that consists of vitamin C and an ethyl group bound to the third carbon position. This makes Vitamin C very stable and soluble in both water and oil.
However, for a Vitamin C derivative to work it's not enough just to be stable, they also have to be absorbed into the skin and be converted there to pure Vitamin C. We have good news regarding the absorption: on top of manufacturer claims, there is some data (animal study) demonstrating in can get into the skin, and it seems to be better at it than Ascorbyl Glucoside, another vitamin C derivative.
Regarding conversion, we can cite only a manufacturers claim saying that EAC is metabolized in the skin into pure ascorbic acid (and the ascorbic acid content of EAC is very high - 86,4% - compared to the usual 50-60% Vitamin C content of other derivatives).
As for the three magic abilities of Vitamin C, we again mostly have only the manufacturer's claims, but at least those are very promising. EAC seems to have both an antioxidant and anti-inflammatory effect, and it's claimed to be able to boost the skin's collagen production. The strong point of EAC though is skin brightening. On top of manufacturer claims, there is also clinical in-vivo (tested on real people) data showing that 2% EAC can improve skin tone and whiten the skin.
Overall, Ethyl Ascorbic Acid is a very promising but not a fully proven Vitamin C derivative. It's worth a try, especially if you are after Vitamin C's skin-brightening effects.
A multi-functional, silky feeling helper ingredient that can do quite many things. It's used as an emulsion stabilizer, solvent and a broad spectrum antimicrobial. According to manufacturer info, it's also a moisturizer and helps to make the product feel great on the skin. It works synergistically with preservatives and helps to improve water-resistance of sunscreens.
PCA stands for Pyrrolidone Carboxylic Acid and though it might not sound like it, it is a thing that can be found naturally in our skin. The sodium salt form of PCA is an important skin-identical ingredient and great natural moisturizer that helps the skin to hold onto water and stay nicely hydrated.
It is a type of algae extract coming from the algae commonly called Irish moss or red seaweed. It is rich in carrageenan, a natural polymer (big molecules from repeated subunits) that acts as a gelling, thickening and stabilizing agent.
It's one of the most commonly used thickeners and emulsion stabilizers. If the product is too runny, a little xanthan gum will make it more gel-like. Used alone, it can make the formula sticky and it is a good team player so it is usually combined with other thickeners and so-called rheology modifiers (helper ingredients that adjust the flow and thus the feel of the formula). The typical use level of Xantha Gum is below 1%, it is usually in the 0.1-0.5% range.
Btw, Xanthan gum is all natural, a chain of sugar molecules (polysaccharide) produced from individual sugar molecules (glucose and sucrose) via fermentation. It’s approved by Ecocert and also used in the food industry (E415).
A common little helper ingredient that helps water and oil to mix together, aka emulsifier.
The number at the end refers to the oil-loving part and the bigger the number the more emulsifying power it has. 20 is a weak emulsifier, rather called solubilizer used commonly in toners while 60 and 80 are more common in serums and creams.
It’s the most commonly used version of pure vitamin E in cosmetics. You can read all about the pure form here. This one is the so-called esterified version.
According to famous dermatologist, Leslie Baumann while tocopheryl acetate is more stable and has a longer shelf life, it’s also more poorly absorbed by the skin and may not have the same awesome photoprotective effects as pure Vit E.
A form of skincare superstar, vitamin C. Even though we are massive vitamin C fans, Ascorbyl Palmitate (AP) is our least favorite. (Btw, if you do not know what the big deal with vitamin C is then you are missing out. You must go and read our geeky details about it.)
So, AP is one of the attempts by the cosmetics industry to solve the stability issues with vitamin C while preserving its benefits, but it seems to fall short on several things.
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.
- Primary fat-soluble antioxidant in our skin
- Significant photoprotection against UVB rays
- Vit C + Vit E work in synergy and provide great photoprotection
- Has emollient properties
- Easy to formulate, stable and relatively inexpensive
An easy-to-formulate, commonly used, nice to have ingredient that’s also called pro-vitamin B5. As you might guess from the “pro” part, it’s a precursor to vitamin B5 (whose fancy name is pantothenic acid).
Its main job in skincare products is to moisturise the skin. It’s a humectant meaning that it can help the skin to attract water and then hold onto it. There is also research showing that panthenol can help our skin to produce more lovely lipids that are important for a strong and healthy skin barrier.
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.
An optical isomer of naturally occurring arbutin (or beta-arbutin). Just like its sibling, alpha-arbutin is also a skin-brightening, depigmenting agent.
Researching the difference between the two kinds of arbutin, you can read in multiple places on the internet that alpha-arbutin is stronger in effect. Unfortunately, it's never backed up with a credible source. :( Our own research resulted in conflicting results: a study from 1995 found that alpha-arbutin is 10x as effective on mouse melanoma as beta-arbutin. On the other hand, a more recent study from 2015 found that beta-arbutin is more effective both on mouse melanoma cells and on human melanoma cells (btw, kojic acid was the most effective on human melanoma cells).
None of the studies we could find is in-vivo (made on real people) anyways, so who knows. We think you cannot go wrong with trying both beta- and alpha-arbutin and see if one works better for you than the other.
We don't have description for this ingredient yet.
Propanediol is a natural alternative for the often used and often bad-mouthed propylene glycol. It's produced sustainably from corn sugar and it's Ecocert approved.
It's quite a multi-tasker: can be used to improve skin moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula.
We don't have description for this ingredient yet.
It’s the - sodium form - cousin of the famous NMF, hyaluronic acid (HA). If HA does not tell you anything we have a super detailed, geeky explanation about it here. The TL; DR version of HA is that it's a huge polymer (big molecule from repeated subunits) found in the skin that acts as a sponge helping the skin to hold onto water, being plump and elastic. HA is famous for its crazy water holding capacity as it can bind up to 1000 times its own weight in water.
As far as skincare goes, sodium hyaluronate and hyaluronic acid are pretty much the same and the two names are used interchangeably. As cosmetic chemist kindofstephen writes on reddit "sodium hyaluronate disassociates into hyaluronic acid molecule and a sodium atom in solution".
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).
Hydrolyzed Hyaluronic Acid is a low molecular weight, chemically chopped up version of the naturally big molecule and current IT-moisturizer, Hyaluronic Acid (HA). The TL; DR version of HA is that it's a huge polymer (big molecule from repeated subunits) found in the skin that acts as a sponge helping the skin to retain water, making it plump and elastic. As HA is a polymer, the subunits can be repeated many times (as a high-molecular-weight version), or just a few times (as a low-molecular-weight version).
We wrote in detail at HA about how different molecular weight versions do different things both as a component of the skin and as a skincare ingredient, so click here and read about all the details. Hydrolyzed Hyaluronic Acid can also come in different molecular-weight versions with different properties:
- 100-300 kDa version: apart from moisturizing, this size might also help the skin to repair itself by increasing its self-defense. It is also claimed to boost the wound healing process and is especially helpful for sensitive skin types (acne, rosacea, inflammation-related skin diseases).
- 50k Da version: this is the size that is claimed to be able to absorb into the skin and plump up wrinkles, so it is used mainly as an "anti-aging ingredient"
- below 50k, around 10k Da version: there is a Japanese version trade named Hyalo-Oligo that has only a 10k molecular weight and is claimed to penetrate the skin very well, have a unique touch and give deep and long-lasting moisturization. Based on the Evonik-research and the natural role of LMW-HA in the body working as a pro-inflammatory signal molecule, this ultra-low molecular weight version is a controversial ingredient.
If you wanna become a real HA-and-the-skin expert, you can read much 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).
- It’s naturally in our skin and behaves there like a sponge
- It can bind up to 1000 times its own weight in water
- It is a big molecule from repeated subunits (polymer) so different molecular weight versions exist (unfortunately there is no way to determine MW from INCI list only)
- High-molecular-weight-HA (>500 kDa) is an excellent surface hydrator, skin protectant and can act as an osmotic pump helping water-soluble actives to penetrate deeper into the skin
- Low-molecular-weight-HA (< 500 kDa) can hydrate the skin somewhat deeper though it is still a big molecule and works mainly in the epidermis (outer layer of the skin)
- Low-molecular-weight-HA might also help the skin to repair itself by increasing its self-defense (~ 200kDa used in the study)
- Ultra-low-molecular-weight-HA (<50kDa) is a controversial ingredient and might work as a pro-inflammatory signal molecule
It's a special "cross-linked" from of IT-moisturizer, hyaluronic acid (HA). Cross-linked means that "normal" HA pieces (1-2 million Da molecular weight) are chemically bound togeather to create a big, "infinite" mesh.
The special HA mesh has a remarkable water-binding capacity, 5 times more than the already crazy water-binding capacity of "normal" HA. This water filled crosslinked HA gel forms a smooth film on the skin and continuously delivers the bound water, so it gives long-term moisturizing benefits.
Btw, crosslinking HA was developed for dermal fillers (as crosslinking helps their longevity), and this guy is the topical version of FDA approved dermal filler called Hylan B gel. Smearing crosslinked version all over ourselves is a newish thing, and incoming evidence so far suggests that it's a great idea, even better than normal HA.
A very recent, 2016 research article compared the topical moisturizing effect of crosslinked HA (not Hylan B gel specifically, but something called Resilient HA or RHA), HMW-HA and LMW-HA and found that "TEWL (that is trans-epidermal water loss, the water that evaporates from the skin) was reduced by 27.8% with RHA, and by 15.6% with HMW HA, but increased by 55.5% with LMW HA." (You can read much more about HMW and LMW HA here in the geeky details section.)
All in all, we think Sodium Hyaluronate Crosspolymer is an awesome version of HA, probably superior to traditional versions, so be happy to spot it on the ingredient list.
A nice little helper ingredient that can thicken up cosmetic products and create beautiful gel formulas. It's derived from cellulose, the major component of the cell wall of green plants. It is compatible with most co-ingredients and gives a very good slip to the formulas.
It’s pretty much the current IT-preservative. It’s safe and gentle, but even more importantly, it’s not a feared-by-everyone-mostly-without-scientific-reason paraben.
It’s not something new: it was introduced around 1950 and today it can be used up to 1% worldwide. It can be found in nature - in green tea - but the version used in cosmetics is synthetic.
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.
An Ecocert-approved, natural preservative that counts as gentle and non-irritating to the skin. Usually, it comes to the formula as part of a preservative blend as it's not enough on its own.
We have to start by writing that there are about 900 citrus species in the world, and plenty of them are used to make different kinds of extracts used in cosmetics. This particular one, Citrus Aurantium Dulcis Fruit Extract is a very common ingredient, however, the species "Citrus Aurantium Dulcis" seem to exist only on ingredient lists and the real world calls this guy Citrus Sinensis or, you know, orange.
To complicate matters further, there are lots of varieties and lots of extraction methods, so it is a bit hard to know what you are getting with this one, but we will try our best to summarize the possibilities.
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.
You might know licorice as a sweet treat from your childhood, but it's actually a legume that grows around the Mediterranean Sea, the Middle East, central and southern Russia. It's sweet and yellow and not only used for licorice all sorts but it's also a skincare superstar thanks to two magic properties:
Nr. 1 magic property is that it has skin-lightening or to say it another way depigmenting properties. The most active part is called glabridin. The topical application (meaning when you put it on your face) of 0.5% glabridin was shown to inhibit UVB caused pigmentation of guinea pigs. Another study even suggested that licorice is more effective than the gold standard skin-lightening agent hydroquinone. All in all, licorice is considered to be one of the safest skin lightening agents with the fewest side effects.
There is just one catch regarding glabridin and licorice: the amount of glabridin in commercial licorice extracts can vary a lot. We have seen extracts with only 4% glabridin as well as 40% glabridin. The latter one is a very-very expensive ingredient, so if you are after the depigmenting properties try to choose a product that boasts its high-quality licorice extract.
Nr. 2 magic property is that licorice is a potent anti-inflammatory. Glabridin has also some soothing properties but the main active anti-inflammatory component is glycyrrhizin. It’s used to treat several skin diseases that are connected to inflammation including atopic dermatitis, rosacea or eczema.
Oh, and one more thing: glabridin seems to be also an antioxidant, which is just one more reason to be happy about licorice root extract on an ingredient list.
Bottom line: Licorice is a great skincare ingredient with significant depigmenting, anti-inflammatory and even some antioxidant properties. Be happy if it's on the ingredient list. :)
- Green tea is one of the most researched natural ingredients
- The active parts are called polyphenols, or more precisely catechins (EGCG being the most abundant and most active catechin)
- There can be huge quality differences between green tea extracts. The good ones contain 50-90% catechins (and often make the product brown and give it a distinctive smell)
- Green tea is proven to be a great antioxidant, UV protectant, anti-inflammatory, anticarcinogenic and antimicrobial
- Because of these awesome properties green tea is a great choice for anti-aging and also for skin diseases including rosacea, acne and atopic dermatitis
We don't have description for this ingredient yet.
The unfancy name for it is lye. It’s a solid white stuff that’s very alkaline and used in small amounts to adjust the pH of the product and make it just right.
For example, in case of AHA or BHA exfoliants, the right pH is super-duper important, and pH adjusters like sodium hydroxide are needed.
BTW, lye is not something new. It was already used by ancient Egyptians to help oil and fat magically turn into something else. Can you guess what? Yes, it’s soap. It still often shows up in the ingredient list of soaps and other cleansers.
Sodium hydroxide in itself is a potent skin irritant, but once it's reacted (as it is usually in skin care products, like exfoliants) it is totally harmless.
You may also want to take a look at...
| what‑it‑does | solvent |
| what‑it‑does | antioxidant | skin brightening | buffering |
| what‑it‑does | moisturizer/humectant | solvent |
| irritancy, com. | 0, 1 |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | antioxidant | skin brightening |
| what‑it‑does | solvent | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | viscosity controlling |
| what‑it‑does | viscosity controlling |
| what‑it‑does | emulsifying |
| what‑it‑does | emulsifying | surfactant/cleansing |
| irritancy, com. | 0, 0 |
| what‑it‑does | antioxidant |
| irritancy, com. | 0, 0 |
| what‑it‑does | antioxidant |
| irritancy, com. | 0, 2 |
| what‑it‑does | antioxidant |
| irritancy, com. | 0-3, 0-3 |
| what‑it‑does | soothing | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | antioxidant | skin brightening |
| what‑it‑does | skin brightening | soothing |
| what‑it‑does | solvent | moisturizer/humectant |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | antioxidant | moisturizer/humectant |
| what‑it‑does | viscosity controlling |
| what‑it‑does | preservative |
| what‑it‑does | preservative |
| what‑it‑does | soothing | skin brightening |
| what‑it‑does | antioxidant | soothing |
| what‑it‑does | perfuming |
| what‑it‑does | buffering |