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Paula's Choice Resist Youth-Extending Daily Hydrating Fluid Spf 50

Paula's Choice
Resist Youth-Extending Daily Hydrating Fluid Spf 50

Broad-spectrum sun protection formulated with antioxidants; water-light texture with a satin-matte finish.
Uploaded by: amanicke on 23/10/2017

Paula's Choice Resist Youth-Extending Daily Hydrating Fluid Spf 50
Ingredients explained

Also-called: Butyl Methoxydibenzoylmethane | What-it-does: sunscreen

The famous Avobenzone. It is a special snowflake as it is the only globally available chemical sunscreen agent that provides proper UVA protection (in the US, new generation sunscreen agents are not approved because of impossible FDA regulations). It is the global gold standard of UVA protection and is the most used UVA sunscreen in the world. 

It gives very good protection across the whole UVA range (310-400 nm that is both UVA1 and UVA2) with a peak protection at 360 nm. The problem with it, though, is that it is not photostable and degrades in the sunlight. Wikipedia says that avobenzone loses 36% of its UV-absorption capacity after just one hour of sunlight (yep, this is one of the reasons why sunscreens have to be reapplied after a few hours).

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The cosmetic's industry is trying to solve the problem by combining avobenzone with other UV filters that enhance its stability (like octocrylene, Tinosorb S or Ensulizole) or by encapsulating it and while both solutions help, neither is perfect. Interestingly, the combination of avobenzone with mineral sunscreens (that is titanium dioxide and zinc oxide) is not a good idea. In the US, it is flat out prohibited as avobenzone becomes unstable when combined with mineral sunscreens.

As for safety, avobenzone has a pretty good safety profile. It counts as non-irritating, and unlike some other chemical sunscreens, it shows no estrogenic effect. The maximum concentration of avobenzone permitted is 5% in the EU and 3% in the US.

Also-called: Octinoxate, Octyl Methoxycinnamate;Ethylhexyl Methoxycinnamate | What-it-does: sunscreen | Irritancy: 0 | Comedogenicity: 0

A clear, oil-soluble, "cosmetically-elegant" liquid that is the most commonly used chemical sunscreen. It absorbs UVB radiation (at wavelengths: 280-320 nm) with a peak protection at 310nm. 

It only protects against UVB and not UVA rays (the 320-400 nm range) – so always choose products that contain other sunscreens too. It is not very stable either, when exposed to sunlight, it kind of breaks down and loses its effectiveness (not instantly, but over time - it loses 10% of its SPF protection ability within 35 mins). To make it more stable it can be - and should be - combined with other sunscreen agents to give stable and broad-spectrum protection (the new generation sunscreen agent, Tinosorb S is a particularly good one for that).

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Regarding safety, there are also some concerns around Octinoxate. In vitro (made in the lab not on real people) and animal studies have shown that it may produce hormonal (estrogen-like) effects. Do not panic, the studies were not conducted under real life conditions on real human people, so it is probably over-cautious to avoid Octinoxate altogether. However, if you are pregnant or a small child (under 2 yrs. old), choose a physical (zinc oxide/titanium dioxide) or new-generation Tinosorb based sunscreen, just to be on the super-safe side. :) 

Overall, Ethylhexyl Methoxycinnamate is an old-school chemical sunscreen agent. There are plenty of better options for sun protection today, but it is considered "safe as used" (and sunscreens are pretty well regulated) and it is available worldwide (can be used up to 10% in the EU and up to 7.5% in the US).

Also-called: Octyl Salicylate, Octisalate;Ethylhexyl Salicylate | What-it-does: sunscreen | Irritancy: 0 | Comedogenicity: 0

A colorless to light yellowish oily liquid that works as a UVB (280-320nm) sunscreen filter with a peak absorbance at 306 nm. It's not a strong filter in itself, it's always used in combination with other sunscreen agents to further enhance the SPF and to solubilize other solid UV filters.

It has a good safety profile and is allowed to be used at a max concentration of 5% both in the US and in Europe (10% is allowed in Japan).

What-it-does: sunscreen

An oil-soluble chemical sunscreen agent that protects skin in the UVB and somewhat in the UVA II range with a peak absorption of 304 nm. Its protection is not strong enough on its own but it is quite photostable (looses 10% of SPF protection in 95 mins) and is often used to stabilize other photo-unstable UV-filters, for example, Avobenzone. It is also often used to improve the water resistance of the products. 

Octocrylene's safety profile is generally quite good, though a review study in Contact Dermatitis reports an "increasing number of patients with photo contact allergy to octocrylene." Mainly adults with ketoprofen-sensitivity and children with sensitive skin are affected, so if you have a small kid, it is probably better to use octocrylene-free sunscreens.

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 >>

A white powdery thing that's the major component of glass and sand. In cosmetics, it’s often in products that are supposed to keep your skin matte as it has great oil-absorbing abilities. It’s also used as a helper ingredient to thicken up products or suspend insoluble particles. 

What-it-does: emollient | Irritancy: 0 | Comedogenicity: 1

Probably the cheapest and most common silicone of all. It is a polymer (created from repeating subunits) molecule and has different molecular weight and thus different viscosity versions from water-light to thick liquid.

As for skincare, it makes the skin silky smooth, creates a subtle gloss and forms a protective barrier (aka occlusive). Also, works well to fill in fine lines and wrinkles and give skin a plump look (of course that is only temporary, but still, it's nice). There are also scar treatment gels out there using dimethicone as their base ingredient. It helps to soften scars and increase their elasticity. 

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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). 

Tocopherol - superstar
Also-called: Vitamin E | What-it-does: antioxidant | Irritancy: 0-3 | Comedogenicity: 0-3
  • 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
Read all the geeky details about Tocopherol here >>

Also-called: German Chamomile Flower Extract | What-it-does: soothing, antioxidant | Irritancy: 0 | Comedogenicity: 0

Chamomile probably needs no introduction as it's one of the most widely used medicinal herbs. You probably drink it regularly as a nice, calming cup of tea and it's also a regular on skincare ingredient lists.

Cosmetic companies use it mainly for its anti-inflammatory properties. It contains the terpenoids chamazulene and bisabolol both of which show great anti-inflammatory action in animal studies. On top of that chamomile also has some antioxidant activity (thanks to some other active ingredients called matricine, apigenin and luteolin).  

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

Also-called: Grape Seed Extract | What-it-does: antioxidant

We wholeheartedly support the rise of seedless grapes as fruit snacks, but when it comes to skincare, we are big fans of the seeds.

They contain the majority of the skin goodies that -  similar to green tea - are mostly polyphenols (but not the same ones as in tea). The most abundant ones in grape are called proanthocyanidins, and 60-70% of them are found in the seeds (it's also often abbreviated as GSP - grape seed proanthocyanidins). In general, the darker the fruit, the more GSPs and other flavonoids it contains.

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So what's so special about GSPs? Well, they are super-potent antioxidants, much stronger than Vitamin C or Vitamin E. And if that's not enough, GSPs and other flavonoids in grape also show UV protecting and anti-cancer properties.

It's definitely a goodie to spot on the INCI list.

Also-called: Green Tea | What-it-does: antioxidant, soothing, antimicrobial/antibacterial
  • 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
Read all the geeky details about Camellia Sinensis Leaf Extract here >>

Also-called: tea oil camellia;Camellia Oleifera Leaf Extract | What-it-does: antioxidant, soothing

Camellia Oleifera is a type of green tea plant that's mostly known for the oil that comes from its seeds. As for the leaves, it has similar properties as the better known and more often used Camellia Sinensis leaves. You can read all the geeky details about green tea  and why it's awesome by clicking here, but in short, it has antioxidants and anti-inflammatory magic properties.

We don't have description for this ingredient yet.

Also-called: Elderberry Fruit Extract | What-it-does: astringent

We don't have description for this ingredient yet.

What-it-does: soothing

We don't have description for this ingredient yet.

What-it-does: astringent

We don't have description for this ingredient yet.

Also-called: Goji Berry Extract | What-it-does: astringent

We don't have description for this ingredient yet.

What-it-does: emollient, emulsifying

It's the chemically chopped up version of normal lecithin. Most often it's used to create liposomes and to coat and stabilize other ingredients. 

What-it-does: sunscreen

Titanium Dioxide is one of the two members of the elite sunscreen group called physical sunscreens (or inorganic sunscreens if you’re a science geek and want to be precise).

Traditionally, UV-filters are categorized as either chemical or physical. The big difference is supposed to be that chemical agents absorb UV-light while physical agents reflect it like a bunch of mini umbrellas on top of the skin. While this categorization is easy and logical it turns out it's not true. A recent, 2016 study shows that inorganic sunscreens work mostly by absorption, just like chemical filters, and only a little bit by reflection (they do reflect the light in the visible spectrum, but mostly absorb in the UV spectrum).

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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. 

What-it-does: viscosity controlling

A white, elastomeric silicone powder that gives a nice silky and powdery feel to the products. It also has some oil and sebum absorption capabilities. 

A handy helper ingredient that has photostabilizer properties. It is useful both for color-protecting products so that they do not change color for a long time as well as for stabilizing unstable sunscreen agents, such as famous UVA filter avobenzone

DESM can also increase critical wavelength (the higher value means more UVA protection) in sunscreens and it can boost SPF by about 5 units in high-SPF products. 

Also-called: Sepinov EMT 10 | What-it-does: viscosity controlling, emulsion stabilising

This long-named, polymer molecule (big molecule from repeated subunits) is a helper ingredient that's good at emulsifying and stabilizing oils into water-based formulas. It also acts as a thickening and gelling agent that creates nice, non-sticky and supple textures. It works over a very wide pH range (3-12) and can be used to thicken up low-ph formulas, such as exfoliants.

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: viscosity controlling

A pre-neutralised form of super common thickener, Carbomer. This means that it forms viscous gels immediately upon addition to water (while Carbomer has to be neutralized with a base), but it can also be harder to disperse evenly in the formula. 

It's one of those things that help your cosmetics not to go wrong too soon, aka a preservative. It can be naturally found in fruits and teas but can also be made synthetically.

No matter the origin, in small amounts (up to 1%) it’s a nice, gentle preservative. Has to be combined with some other nice preservatives, like potassium sorbate to be broad spectrum enough.  

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In high amounts, it can be a skin irritant, but don’t worry, it’s never used in high amounts.

What-it-does: preservative

A helper ingredient that helps to make the products stay nice longer, aka preservative. It works mainly against fungi. 

It’s pH dependent and works best at acidic pH levels (3-5). It’s not strong enough to be used in itself so it’s always combined with something else, often with potassium sorbate.

What-it-does: preservative

It's one of those things that help your cosmetics not to go wrong too soon, aka a preservative. It’s not a strong one and doesn’t really work against bacteria, but more against mold and yeast. To do that it has to break down to its active form, sorbic acid. For that to happen, there has to be water in the product and the right pH value (pH 3-4). 

But even if everything is right, it’s not enough on its own. If you see potassium sorbate you should see some other preservative next to it too.

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BTW, it’s also a food preservative and even has an E number, E202.

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.

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

what‑it‑does sunscreen
Avobenzone - the only globally available chemical sunscreen that gives proper UVA protection. It is not photostable so has to be combined with ingredients that help to stabilize it. [more]
what‑it‑does sunscreen
irritancy, com. 0, 0
Octinoxate - an old-school chemical sunscreen that absorbs UVB radiation (wavelengths: 280-320 nm). Not photostable and does not protect against UVA. [more]
what‑it‑does sunscreen
irritancy, com. 0, 0
A colorless to light yellowish oily liquid that works as a UVB (280-320nm) sunscreen filter with a peak absorbance at 306 nm. It's not a strong filter in itself, it's always used in combination with other sunscreen agents. [more]
what‑it‑does sunscreen
An oil-soluble chemical sunscreen agent that protects skin in the UVB and somewhat in the UVA II range with a peak absorption of 304 nm. [more]
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 viscosity controlling | abrasive/scrub
A white powdery thing that can mattify the skin and thicken up cosmetic products. [more]
what‑it‑does emollient
irritancy, com. 0, 1
A very common silicone that gives both skin and hair a silky smooth feel. It also forms a protective barrier on the skin and fills in fine lines. Also used for scar treatment. [more]
what‑it‑does antioxidant
irritancy, com. 0-3, 0-3
Pure Vitamin E. Great antioxidant that gives significant photoprotection against UVB rays. Works in synergy with Vitamin C. [more]
what‑it‑does soothing | antioxidant
irritancy, com. 0, 0
Chamomile extract - has great anti-inflammatory and some antioxidant properties. [more]
what‑it‑does antioxidant
Grape Seed Extract - contains awesome polyphenols that are super-potent antioxidants and also have UV-protecting and anti-cancer properties. [more]
what‑it‑does antioxidant | soothing | antimicrobial/antibacterial
Green Tea - one of the most researched natural ingredients that contains the superstar actives called catechins. It has proven antioxidant, anti-inflammatory, antimicrobial and anticarcinogenic properties. [more]
what‑it‑does antioxidant | soothing
A type of green tea that has antioxidants and anti-inflammatory properties. [more]
what‑it‑does soothing
what‑it‑does emollient | emulsifying
It's the chemically chopped up version of normal lecithin. Most often it's used to create liposomes and to coat and stabilize some other ingredient. 
what‑it‑does sunscreen
A physical/inorganic sunscreen with pretty broad spectrum (UVB and UVA II, less good at UVA I) protection and good stability. Might leave some whitish tint on the skin, though. [more]
what‑it‑does viscosity controlling
A white, elastomeric silicone powder that gives a nice silky and powdery feel to the products. [more]
A photostabilizer that has color protecting as well as sunscreen agent stabilizing properties. [more]
what‑it‑does viscosity controlling
A helper ingredient that's good at stabilizing water-based formulas and also serves as a thickener. [more]
what‑it‑does viscosity controlling
A super commonly used thickener and emulsion stabilizer. [more]
what‑it‑does viscosity controlling
A pre-neutralised form of super common thickener, Carbomer. This means that it forms viscous gels immediately upon addition to water (while Carbomer has to be neutralized with a base), but it can also be harder to disperse evenly in the formula.  [more]
what‑it‑does preservative | perfuming | solvent | viscosity controlling
It's one of those things that help your cosmetics not to go wrong too soon, aka a preservative. It can be naturally found in fruits and teas but can also be made synthetically. No matter the origin, in small amounts (up to 1%) it’s a nice, gentle preservative. [more]
what‑it‑does preservative
A preservative that works mainly against fungi. Has to be combined with other preservatives. [more]
what‑it‑does preservative
A not so strong preservative that doesn’t really work against bacteria, but more against mold and yeast. [more]
what‑it‑does preservative
Pretty much the current IT-preservative. It’s safe and gentle, and can be used up to 1% worldwide. [more]