Hydrating Infused Emulsion
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La Mer Hydrating Infused EmulsionIngredients 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.
We have to admit that Algae Extract is not our favorite ingredient name. It does comply with the INCI standard (the official list about how ingredients on the product labels have to be called, the thing we help you to decode here :)), but there are about 20 000 different kinds of algae and an extract from them can be made in another 10 000 ways.
So, Algae Extract can be anything from La Mer's "Miracle Broth" to a simple brown algae extract that helps to smooth the hair. The official description in the Europiean Cosmetic Ingredient listing is this: "an extract of various species of Algae; Extract of the Seaweed, Fucus vesiculosus, Furaceae". Its official functions include being a humectant (helps skin to attract water), emollient (makes skin feel smooth and nice) and skin conditioner (a catchall phrase for saying it does something good for the skin).
A 2015 research paper on the potential of uses of algae in cosmetics summarizes that algae are rich sources of biologically active metabolites including antioxidants, anti-inflammatory agents, alginates, polysaccharides, and carotenoids. Currently, algae extracts are mostly used as moisturizing and thickening agents, but algae also have great potential to combat skin aging, pigmentation as well as working as an antimicrobial.
We have also browsed through Prospector to see what manufacturers say about their algae. There is, for example, an algae extract trade-named Lanablue that comes from blue-green algae (green algae is rare, less than 1% of the total macroalgae in the world) and is claimed to have retinoid like effects (i.e. reduce wrinkles, smooth skin) but without the side effects (though it seems now that the INCI name of Lanablue was changed to Aphanizomenon Flos-Aquae Extract).
There is another algae extract from another manufacturer that comes from red algae (much more common, about 40% of total macroalgae worldwide) and is claimed to have not only moisturizing but also skin smoothing and densifying effects.
Here is a brown algae extract (the most common type, about 59% of macroalgae), also just called Algae Extract on the product label that is simply claimed to be a free radical scavenger, aka antioxidant. These were just three random examples from three manufacturers all called Algae extract even though they all come from different algae with different claims.
Anyhow, the point is this; there are tons of different types of Algae Extracts out there. Unless the brand tells you what they use, it's impossible to know for sure. The most probable scenario for the Alge Extract is that it works as a moisturizer and emollient and it might have some additional anti-aging properties.
It seems to us that squalane is in fashion and there is a reason for it. Chemically speaking, it is a saturated (no double bonds) hydrocarbon (a molecule consisting only of carbon and hydrogen), meaning that it's a nice and stable oily liquid with a long shelf life.
It occurs naturally in certain fish and plant oils (e.g. olive), and in the sebum (the oily stuff our skin produces) of the human skin. As f.c. puts it in his awesome blog post, squalane's main things are "emolliency, surface occlusion, and TEWL prevention all with extreme cosmetic elegance". In other words, it's a superb moisturizer that makes your skin nice and smooth, without being heavy or greasy.
Another advantage of squalane is that it is pretty much compatible with all skin types and skin conditions. It is excellent for acne-prone skin and safe to use even if you have fungi-related skin issues, like seborrhea or fungal acne.
The unsaturated (with double bonds) and hence less stable version of Squalane is Squalene, you can read about it here >>
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
The emollient plant oil coming from the seeds of the white flowering plant called meadowfoam. Meadowfoam Oil has a unique fatty acid composition with 95% of it being long chain fatty acids (eicosenoic acid C20:1 - 61%, docosenoic acid C22:1 - 16% and docosadienoic acid C22:2 - 18%) that make the oil extraordinarily stable. It also contains antioxidant components such as vitamin E as well as phytosterols.
Apart from Meadowfoam Oil's crazy stability, the oil is described as non-greasy, rapidly absorbed and having a similar skin feel to more often used jojoba oil. The oil is ideal for products where a soft, smooth, silky feel is required whether it be on skin or hair.
A thick, paste-like emollient ester that is touted as a vegetable-derived lanolin alternative. It has a smooth spreadability and touch, and it gives a substantive film to protect and moisturize the skin.
A silicone fluid that gives a nonoily, easy to spread emolliency to the formulas. It is also used as a water repellent additive and to reduce the tackiness and stickiness of other ingredients. It also imparts gloss, softness and better manageability to hair.
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.
A goldish to dark yellow emollient plant oil coming from Sesame seeds. Similar to many other plant oils, it contains high amounts of nourishing and moisturizing fatty acids (about 38% of oleic and 48% of linoleic acid) and is a nice oil to repair and regenerate dry skin. It is rapidly absorbed and gives the skin a soft and gentle feel.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
The essential oil created by steam distilling the leaves of the Eucalyptus tree. It's a colorless, pale yellow oil with a camphoraceous aroma used traditionally in vapor rubs to treat coughs. Its name-giving main component is eucalyptol (also called 1,8-cineole, 80-91%) that has significant antibacterial and expectorant properties.
Among essential oils, Eucalyptus Globulus counts as rather non-sensitising with an EU sensitizer total of 5% (due to limonene). However, if your skin is super-sensitive or you are allergic to fragrances, it is still better to avoid it.
The neutralized form of gluconic acid. It's a great ingredient to neutralize metal (especially iron and copper) ions in a cosmetic product. This helps to prevent discoloration of the formula over time or rancidity of cosmetic oils. It can also be a pH regulator and a humectant (helps skin to cling onto water).
It's also used in oral care products where it reduces the bitterness of other ingredients. And it's natural, both Ecocert and Cosmos approved. (source: manufacturer info)
A copper salt (copper cation + gluconate anion) probably best known for promoting cellular regeneration and wound healing. It works mainly in the final healing phase that complements nicely with the wound healing abilities of its mineral salt sister, zinc gluconate.
Other than that, copper is also involved in several enzyme systems: it is a cofactor for the antioxidant enzyme, superoxide dismutase and also a cofactor for the melanin stimulating enzyme, tyrosinase. This means that copper has some tan activating properties, though we think you should not be into tanning at all, as UV is so bad for the skin.
The gluconate part is there to promote the bioavailability of copper and it also plays a role in cellular regeneration (involved in the synthesis of ribose sugars, structural components of DNA and RNA).
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
If you are fighting acne and have looked into oral supplements, chances are that zinc gluconate sounds familiar to you. It is a zinc salt that has research proving it to be effective against inflammatory acne, though not quite as effective as the antibiotic minocycline (31.2% vs. 63.4% success rate). However, zinc supplements are easily available, have little-to-no side effects, so supplementing them with a 30mg per day dose can still be a good idea.
As for smearing zinc gluconate all over your face, it is also not a bad idea. Zinc has multiple magic abilities: it is antibacterial (including evil, acne-causing P. acnes) and sebum-regulating (5α-reductase inhibitor), great for acne-prone skin types. It also stimulates antioxidant enzyme systems (mainly superoxide dismutase) and has nice wound healing abilities acting mainly in the first, proliferation phase. So great for skin types in need of healing and soothing.
What about the gluconate part? It is there to promote the absorption and bioavailability of zinc and also plays a role in cellular regeneration (involved in the synthesis of ribose sugars, structural components of DNA and RNA).
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
Soy Amino Acids are the little components that come from totally chopping up a soy protein. It is a low-molecular-weight water-binding ingredient, that can help to moisturize deeper layers of skin or hair.
We don't have description for this ingredient yet.
You probably know olive oil from the kitchen as a great and healthy option for salad dressing but it's also a great and healthy option to moisturize and nourish the skin, especially if it's on the dry side.
Similar to other emollient plant oils, it's loaded with nourishing fatty acids: oleic is the main component (55-83%), and also contains linoleic (3.5-20%) and palmitic acids (7-20%). It also contains antioxidant polyphenols, tocopherols (types of vitamin E) and carotenoids and it's one of the best plant sources of skin-identical emollient, Squalene.
Overall, a great option for dry skin but less so for acne-prone or damaged skin.
We don't have description for this ingredient yet.
If you see a cosmetic product that claims that it has "Botox-like effect" then two things are almost certain: one, the product overpromises and two, it contains Argireline.
So this one is the famous peptide that's marketed by its manufacturer as the "Botox in a jar". The basis for this claim is that it targets the same wrinkle forming mechanism (wrinkles caused by facial muscle movement) as Botox, but the way it works is very different. In addition, the extent to which it can prevent muscles from contracting (and to smooth wrinkles) is very different (otherwise why would anyone use still Botox?).
The manufacturer did several studies to prove that Argireline really works and it does (just not as well as Botox). In-vivo (made on real people) tests showed that using 10% Argireline solution around the eyes for 15 days decreased wrinkles depth by 17%, while a 5% Argireline formula applied for 28 days did almost the same with a decrease in wrinkle depth by 16.26%. A Spanish University also did some research and found that Argireline increased the level of skin moisturization and decreased both the depth and width of wrinkles "significantly".
This means, Acetyl Hexapeptide-8 does have some ability to smooth wrinkles (but not as well as Botox - sorry, if we sound like a broken record). Also, we have to agree with TruthInAging, that it's not a collagen builder and not a preventer of structural aging (think vitamin C, AHAs or retinol); it's just a quick fix. If you are looking for one, this could be your thing. If you are more of a "let's treat this aging thing properly" type, then it's probably not your thing.
We don't have description for this ingredient yet.
Lactobacillus ferment is an interesting probiotic ingredient with some promising properties.
First, according to a 2009 Estee Lauder patent, it’s a DNA repair enzyme and it can help to protect the skin against environmental aggressors.
Second, still according to Estee Lauder research but now from 2012 the ingredient has anti-microbial and anti-inflammatory properties and holds promise in the treatment of acne and rosacea. For the former one 5% was needed to show effectiveness, but for reducing skin sensitivity already 1% showed results.
The anti-acne effect is confirmed also by US manufacturer, Barnet, that says that Lactobacillus ferment is helpful in killing harmful bacteria and creating a healthy balanced microflora. Compared to well-known anti-acne and anti-inflammatory salicylic acid the probiotic worked faster at reducing the size and redness of acne lesions.
It also goes by the trade name Leucidal Liquid SF and can serve in the formula as a natural preservative.
Bottom line: It’s not the most proven ingredient (yet) but definitely a very promising one especially if you have sensitive skin, acne or rosacea.
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).
We don't have description for this ingredient yet.
Hello, our favorite molecule that helps us wake up in the morning and then keeps us going through the day. As a super well-known stimulant from coffee, tea and plenty of other soft drinks, Caffeine needs no introduction. So we will skip right to the part where we talk about what the hell it does in so-so many cosmetic products.
Looking at the research, we were surprised to find how versatile Caffeine is. It is a small, water-loving molecule with pretty good skin penetration abilties. Once in the skin, it has nice antioxidant properties, meaning that it reduces the formation of evil free radicals and it might even be useful in preventing UV-induced skin cancers.
A well-known thing about Caffeine is that it improves the microcirculation of the blood vessels. Though conventional wisdom and anecdotal evidence says that this property is helpful for dark under-eye circles and puffy eyes, we have to mention that the double-blind research we have found about a 3% caffeine gel concluded that "the overall efficacy of the selected caffeine gel in reducing puffy eyes was not significantly different from that of its gel base." But you know, the proof is in the pudding.
Another thing Caffeine is used for in body care products is its anti-cellulite effects. In theory, it can speed up the lipolysis process (the "fat burning" by our cells) and stimulate the draining lymph system that might lead to the improvement of cellulite. But here again, the evidence that it actually makes a measurable, let alone visible, improvement on actual human beings is limited (we could find only some animal skin studies or caffeine being combined with other actives).
Last, but not least, we have to write about caffeine and hair growth. The theory is that it can inhibit the activity of the 5-α-reductase enzyme that plays an important role in hair loss and allows a renewed growth phase of the hair. We have found some recent and promising research to back this up. A 2017 study compared a 0.2% caffeine liquid with a 5% Minoxidil (an FDA approved active to treat baldness) solution and found that "a caffeine-based topical liquid should be considered as not inferior to minoxidil 5% solution in men with androgenetic alopecia", or English translation means that the caffeine liquid was pretty much as good as the FDA-approved Minoxidil stuff. Not bad!
Overall, we think that caffeine is a very versatile and biologically active ingredient. Even though some of its effects are more hyped up than backed up, it is still a nice to have on many ingredient lists.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
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.
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 type of sugar that has water-binding properties and helps to keep your skin hydrated.
The salt form of one of the main anti-inflammatory ingredients in the licorice plant, monoammonium glycyrrhizinate. It’s a yellowish powder with a nice sweet smell.
It’s used mainly for its soothing and anti-inflammatory properties, but according to manufacturer info, it’s also sebum regulating so it's a perfect ingredient for problem skin products.
Read more about licorice and why it's a skincare superstar here.
A super common emollient that makes your skin feel nice and smooth. It comes from coconut oil and glycerin, it’s light-textured, clear, odorless and non-greasy. It’s a nice ingredient that just feels good on the skin, is super well tolerated by every skin type and easy to formulate with. No wonder it’s popular.
A kind of polymer (big molecule from repeated subunits) that helps to create beautiful gel-like textures. It's also a texturizer and thickener for oil-in-water emulsions. It gives products a good skin feel and does not make the formula tacky or sticky.
It works over a wide pH range and is used between 0.5-1.2%.
It's a helper ingredient that helps to thicken up formulas and form a nice gel texture. It leaves a rich, elegant feel with a velvety finish on the skin and works over a wide pH range.
Tetrahexyldecyl Ascorbate is a stable, oil-soluble form of skincare big shot Vitamin C. If you do not know, why Vitamin C is such a big deal in skincare, click here and read all about it. We are massive vitamin C fans and have written about it in excruciating detail.
So now, you know that Vitamin C is great and all, but it's really unstable and gives cosmetics companies many headaches. To solve this problem they came up with vitamin C derivatives, and one of them is Tetrahexyldecyl Ascorbate (let's call it THDA in short).
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).
A type fo sugar, usually refined from cane or beet sugar. On the skin, it has water-binding properties and helps to keep your skin hydrated.
Probably the 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.
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).
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).
- It's a super common and super debated skincare ingredient
- It has several benefits: great solvent, penetration enhancer, creates cosmetically elegant, light formulas, great astringent and antimicrobial
- It can be very drying if it's in the first few ingredients on an ingredient list
- Some experts even think that regular exposure to alcohol damages skin barrier and causes inflammation though it's a debated opinion (read more in geeky details tab)
A clear liquid with a camphor-like odor that is used as a solvent.
Exactly what it sounds: nice smelling stuff put into cosmetic products so that the end product also smells nice. Fragrance in the US and parfum in the EU is a generic term on the ingredient list that is made up of 30 to 50 chemicals on average (but it can have as much as 200 components!).
If you are someone who likes to know what you put on your face then fragrance is not your best friend - there's no way to know what’s really in it.
Also, if your skin is sensitive, fragrance is again not your best friend. It’s the number one cause of contact allergy to cosmetics. It’s definitely a smart thing to avoid with sensitive skin (and fragrance of any type - natural is just as allergic as synthetic, if not worse!).
Linalool is a super common fragrance ingredient. It’s kind of everywhere - both in plants and in cosmetic products. It’s part of 200 natural oils including lavender, ylang-ylang, bergamot, jasmine, geranium and it can be found in 90-95% of prestige perfumes on the market.
The problem with linalool is, that just like limonene it oxidises on air exposure and becomes allergenic. That’s why a product containing linalool that has been opened for several months is more likely to be allergenic than a fresh one.
A study made in the UK with 483 people tested the allergic reaction to 3% oxidised linalool and 2.3% had positive test results.
A common fragrance ingredient that has a sweet scent somewhere between lily and fruity melon. Can be found in essential oils, such as lavender oil, orange flower oil or ylang-ylang.
In cosmetics, it can be used up to 1%. It’s one of the “EU 26 fragrances” that has to be labelled separately (and cannot be simply included in the term “fragrance/perfume” on the label) because of allergen potential. Best to avoid if your skin is sensitive.
Citronellol is a very common fragrance ingredient with a nice rose-like odor. In the UK, it’s actually the third most often listed perfume on the ingredient lists.
It can be naturally found in geranium oil (about 30%) or rose oil (about 25%).
As with all fragrance ingredients, citronellol can also cause allergic contact dermatitis and should be avoided if you have perfume allergy. In a 2001 worldwide study with 178 people with known sensitization to fragrances citronellol tested positive in 5.6% of the cases.
There is no known anti-aging or positive skin benefits of the ingredient. It’s in our products to make it smell nice.
Geraniol is a common fragrance ingredient. It smells like rose and can be found in rose oil or in small quantities in geranium, lemon and many other essential oils.
Just like other similar fragrance ingredients (like linalool and limonene) geraniol also oxidises on air exposure and becomes allergenic. Best to avoid if you have sensitive skin.
A super common and cheap fragrance ingredient. It's in many plants, e.g. rosemary, eucalyptus, lavender, lemongrass, peppermint and it's the main component (about 50-90%) of the peel oil of citrus fruits.
It does smell nice but the problem is that it oxidizes on air exposure and the resulting stuff is not good for the skin. Oxidized limonene can cause allergic contact dermatitis and counts as a frequent skin sensitizer.
Limonene's nr1 function is definitely being a fragrance component, but there are several studies showing that it's also a penetration enhancer, mainly for oil-loving components.
All in all, limonene has some pros and cons, but - especially if your skin is sensitive - the cons probably outweigh the pros.
Super common little helper ingredient that helps products to remain nice and stable for a longer time. It does so by neutralizing the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes.
It is typically used in tiny amounts, around 0.1% or less.
It's the acronym for Butylated Hydroxy Toluene. It's a common synthetic antioxidant that's used as a preservative.
There is some controversy around BHT. It's not a new ingredient, it has been used both as a food and cosmetics additive since the 1970s. Plenty of studies tried to examine if it's a carcinogen or not. This Truth in Aging article details the situation and also writes that all these studies examine BHT when taken orally.
As for cosmetics, the CIR (Cosmetic Ingredient Review) concluded that the amount of BHT used in cosmetic products is low (usually around 0.01-0.1%), it does not penetrate skin far enough to be absorbed into the bloodstream and it is safe to use in cosmetics.
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.
BTW, it’s also a food preservative and even has an E number, E202.
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.
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| what‑it‑does | solvent |
| what‑it‑does | emollient | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | emollient |
| irritancy, com. | 0, 1 |
| 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 | emollient |
| what‑it‑does | emollient |
| what‑it‑does | emollient |
| what‑it‑does | emollient | emulsifying |
| what‑it‑does | emollient |
| irritancy, com. | 0, 1-3 |
| what‑it‑does | abrasive/scrub |
| what‑it‑does | abrasive/scrub |
| what‑it‑does | perfuming | antimicrobial/antibacterial |
| what‑it‑does | chelating | moisturizer/humectant |
| what‑it‑does | soothing |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | anti-acne | soothing |
| what‑it‑does | antioxidant |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | antioxidant | emollient |
| irritancy, com. | 0, 0-2 |
| what‑it‑does | cell-communicating ingredient | moisturizer/humectant |
| what‑it‑does | surfactant/cleansing | perfuming |
| what‑it‑does | soothing | preservative |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | skin brightening |
| what‑it‑does | antioxidant | perfuming |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | antioxidant |
| irritancy, com. | 0, 0 |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | soothing | moisturizer/humectant |
| what‑it‑does | emollient |
| what‑it‑does | viscosity controlling |
| what‑it‑does | viscosity controlling |
| what‑it‑does | antioxidant | skin brightening |
| what‑it‑does | moisturizer/humectant | soothing |
| what‑it‑does | emollient |
| irritancy, com. | 0, 1 |
| what‑it‑does | viscosity controlling |
| what‑it‑does | antimicrobial/antibacterial | solvent | viscosity controlling |
| what‑it‑does | perfuming | solvent |
| what‑it‑does | perfuming |
| what‑it‑does | perfuming |
| what‑it‑does | perfuming |
| what‑it‑does | perfuming |
| what‑it‑does | perfuming |
| what‑it‑does | perfuming | solvent |
| what‑it‑does | chelating |
| what‑it‑does | antioxidant | preservative |
| what‑it‑does | preservative |
| what‑it‑does | preservative |