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This product has been discontinued. See the current version here.
Paula's Choice Resist Hyaluronic Acid Booster

Paula's Choice
Resist Hyaluronic Acid Booster (Discontinued)

This specialized hyaluronic acid anti-aging booster plumps fine lines and helps prevent moisture loss when added to your favorite moisturizer or serum.
Uploaded by: judit on 05/08/2016

Paula's Choice Resist Hyaluronic Acid Booster
Ingredients explained

Also-called: Aqua | What-it-does: solvent

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. 

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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. 

Glycerin - superstar
Also-called: Glycerol | What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0
  • 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 at higher concentrations up to 20-40% (around 10% is a good usability-effectiveness sweet spot)
  • High-glycerin moisturizers are awesome for treating severely dry skin
Read all the geeky details about Glycerin here >>

Yeast Extract - goodie
What-it-does: moisturizer/humectant

You probably know yeast from the kitchen where you put it into milk with a little sugar and then after a couple of minutes brownish bubbles form. That is the fungi fermenting the sugar

As for skin care, yeast contains beta-glucan that is a great soothing ingredient and also a mild antioxidant.  The yeast extract itself is a silky clear liquid that has some great moisturizing, skin protecting and film-forming properties on the skin. 

What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0

It’s the - sodium form - cousin of the famous NMFhyaluronic 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". 

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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).

  • 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
Read all the geeky details about Hyaluronic Acid here >>

Ceramide NP - goodie
Also-called: Ceramide 3 | What-it-does: skin-identical ingredient

One of the many types of ceramides that can be found naturally in the upper layer of the skin. Ceramides make up about 50% of the goopy stuff that's between our skin cells and play a super important role in having a healthy skin barrier and keeping the skin hydrated. It works even better when combined with its pal, Ceramide 1.

We wrote way more about ceramides at ceramide 1, so click here to know more.

Ceramide AP - goodie
Also-called: Ceramide 6 II | What-it-does: skin-identical ingredient

A type of ceramide that can be found naturally in the upper layer of the skin. Ceramides make up 50% of the goopy stuff that's between our skin cells and play a super important role in having a healthy skin barrier and keeping the skin hydrated. 

We have written way more about ceramides at ceramide 1, so click here to know more.

Ceramide EOP - goodie
Also-called: Ceramide 1 | What-it-does: skin-identical ingredient

Ceramides get quite a lot of hype recently and good news: there is a reason for that. But before we go into the details, let's just quickly define what the heck ceramides are:

They are waxy lipids that can be found naturally in the outer layer of the skin (called stratum corneum - SC). And they are there in big amounts! The goopy stuff between our skin cells is called extracellular matrix that consists mainly of lipids. And ceramides are about 50% of those lipids (the other important ones are cholesterol with 25% and fatty acids with 15%). 

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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 type of lipid, a so-called sphingoid base that can be found naturally in the upper layer of the skin. It's found both in "free-form" and as part of famous skin lipids, ceramides.

There is emerging research about Phytosphingosine that shows that it has antimicrobial and cell-communicating properties and is considered part of the skin's natural defense system.

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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. :)

Adenosine - goodie

Adenosine is an important little compound in our body that has a vital cell-signalling role. Research on smearing it on our face is also promising and shows so far a couple of things:

  • It can help with wound healing
  • It’s a good anti-inflammatory agent
  • It might even help with skin’s own collagen production and improve skin firmness and elasticity
  • It helps with barrier repair and protection
  • It might be even useful for the hair helping with hair thickness and hair growth
Cholesterol - goodie
What-it-does: skin-identical ingredient, emollient | Irritancy: 0 | Comedogenicity: 0

It's one of the important lipids that can be found naturally in the outer layer of the skin. About 25% of the goopy stuff between our skin cells consists of cholesterol. Together with ceramides and fatty acids, they play a vital role in having a healthy skin barrier and keeping the skin hydrated. 

Apart from being an important skin-identical ingredient, it's also an emollient and stabilizer

Panthenol - goodie
Also-called: Pro-Vitamin B5 | What-it-does: soothing, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0

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. 

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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. 

We don't have description for this ingredient yet.

What-it-does: moisturizer/humectant, solvent | Irritancy: 0 | Comedogenicity: 1

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.

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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. 

What-it-does: emulsifying

A helper ingredient that's used as a co-emulsifier (meaning next to other emulsifiers in the formula it helps water and oil to mix) and as a stabilization agent for foams. Also, has some antimicrobial activity so it can help to boost the effectiveness of the preservative system.

What-it-does: viscosity controlling | Irritancy: 0 | Comedogenicity: 1

A big molecule created from repeated subunits (a polymer of acrylic acid) that magically converts a liquid into a nice gel formula.  It usually has to be neutralized with a base (such as sodium hydroxide) for the thickening to occur and it creates viscous, clear gels that also feel nice and non-tacky on the skin. No wonder, it is a very popular and common ingredient.

It's one of the most commonly used thickeners and emulsion stabilizers. If the product is too runny, a little of 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). 

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). 

What-it-does: emulsifying, surfactant/cleansing | Irritancy: 0 | Comedogenicity: 0

It's a common little helper ingredient that helps water and oil to mix together. Also, it can help to increase the solubility of some other ingredients in the formula. 

What-it-does: preservative

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. 

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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.

What-it-does: preservative

If you have spotted ethylhexylglycerin on the ingredient list, most probably you will see there also the current IT-preservative, phenoxyethanol. They are good friends because ethylhexylglycerin can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too.

Also, it's an effective deodorant and a medium spreading emollient

You may also want to take a look at...

what‑it‑does solvent
Normal (well kind of - it's purified and deionized) water. Usually the main solvent in cosmetic products. [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
A real oldie but a goodie. Great natural moisturizer and skin-identical ingredient that plays an important role in skin hydration and general skin health. [more]
what‑it‑does moisturizer/humectant
A silky clear liquid that has great moisturizing, skin protecting and film-forming properties on the skin. [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
It's the salt form of famous humectant and natural moisturizing factor, hyaluronic acid. It can bind huge amounts of water and it's pretty much the current IT-moisturizer. [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
A famous natural moisturizing factor that can bind up to 1000 times its own weight in water. Works as an excellent surface hydrator in skincare. [more]
what‑it‑does skin-identical ingredient
Ceramides make up 50% of the goopy stuff that's between our skin cells and play a super important role in having a healthy skin barrier and keeping the skin hydrated.  [more]
what‑it‑does skin-identical ingredient
A type of ceramide that can be found naturally in the upper layer of the skin. Ceramides make up 50% of the goopy stuff that's between our skin cells and play a super important role in having a healthy skin barrier and keeping the skin hydrated.  We have written way more about ceramides at ceramide 1, so click here to know more. [more]
what‑it‑does skin-identical ingredient
Ceramides get quite a lot of hype recently and good news: there is a reason for that. But before we go into the details, let's just quickly define what the heck ceramides are: They are waxy lipids that can be found naturally in the outer layer of the skin (called stratum corneum - SC). [more]
what‑it‑does skin-identical ingredient | cell-communicating ingredient | anti-acne | antimicrobial/antibacterial
A type of lipid that can be found naturally in the skin. Has antimicrobial and cell-communicating properties and is considered to be part of the skin's natural defence system. [more]
what‑it‑does cell-communicating ingredient
An important compound in our body that has a vital cell-signalling role. It is wound healing, anti-inflammatory and can help with barrier repair. [more]
what‑it‑does skin-identical ingredient | emollient
irritancy, com. 0, 0
It's one of the important lipids that can be found naturally in the outer layer of the skin. About 25% of the goopy stuff between our skin cells consists of cholesterol. [more]
what‑it‑does soothing | moisturizer/humectant
irritancy, com. 0, 0
Pro-Vitamin B5 is a goodie that moisturises the skin, has anti-inflammatory, skin protecting and wound healing properties. [more]
what‑it‑does moisturizer/humectant | solvent
irritancy, com. 0, 1
An often used glycol that works as a solvent, humectant, penetration enhancer and also gives a good slip to the products. [more]
what‑it‑does emulsifying
A helper ingredient that's used as a co-emulsifier and as a stabilization agent for foams. [more]
what‑it‑does viscosity controlling
irritancy, com. 0, 1
A handy white powder that magically converts a liquid into a nice gel formula. [more]
what‑it‑does viscosity controlling
A super commonly used thickener and emulsion stabilizer. [more]
what‑it‑does emulsifying | surfactant/cleansing
irritancy, com. 0, 0
It's a common little helper ingredient that helps water and oil to mix together. Also, it can help to increase the solubility of some other ingredients in the formula. 
what‑it‑does preservative
Pretty much the current IT-preservative. It’s safe and gentle, and can be used up to 1% worldwide. [more]
what‑it‑does preservative
It can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too. [more]