Kosas Tinted Face Oil Review

Coco-Caprylate/​Caprate is a mixture of esters of coconut alcohol with caprylic acid which functions as a skin-conditioning agent and emollient.

I reviewed the CIR and found minimal information with respect to this compound.  The closest I could find was the following trademarked compound and its benefits as listed on the vendor’s websites:

• Vantage Liponate™ CCC MB
  • Ultra low viscosity, colorless and odorless dry emollient ester, which is an ideal sensorial alternative to volatile silicone oils.  Can also be incorporated with powders, colorants, UV filters to enhance the solubility of those materials and further improve the skin feel.
  • 100% naturally-derived (from renewable feedstocks), extra light and fast-spreading emollient that can offer a great alternative to volatile dry silicones such as dimethicone.  Is a clear oil that performs as a very light emollient that spreads quickly upon application before leaving a soft and powdery after-feel on skin. Creates an invisible and ultra silky film that provides long-term moisturization.
  • Great biocompatibility with skin and provides skin with incredible softness.
  • Leaves an invisible film that contributes to long-term hydration after application.
  • Use level:  1-10%

Bottom line: Not much can be said about coco-caprylate/​caprate other than that it functions as an emollient and skin-conditioning agent in cosmetics – often leaving a soft and powdery after-feel on the skin.

The name of this has always made me laugh. In fact, a childhood friend of mine and I would always chuckle at the sound of this ingredient in products. Was it “ho-ho-ba” or was it “joe-joe-ba”? Either way, you pronounce it – it’s a functional vehicle for providing natural hydration, moisturizing, and firming capabilities synergistically with other key extracts and essential oils. A number of reviews from scientific literature suggest that jojoba has anti-inflammatory effects and can be used on a variety of skin conditions including skin infections, skin aging, as well as wound healing.

In fact, a 2010 study assessed the hydration and viscoelastic effect of moisturizers containing different herbal ingredients (including jojoba oil) – after 3 weeks of topical application to the skin. The study found that there was a significant increase in skin viscoelasticity (90-95%) and increase in water content of the stratum corneum (upper layer of the skin) by 60-70%.

Bottom line: This funny-sounding oil enhances the penetration of whatever is synergistically formulated into the product. It is considered a vehicle that also provides hydration and promotion of skin elasticity!  It is considered to be the closest botanical oil that mimics our skin’s natural oils.

Octyldodecanol is a long-chain saturated fatty alcohol.  Fatty alcohols occur in components of wax esters in plants and animals and are often used as emulsifiers, emollients, antifoaming agents, and surfactants.  

In general, octyldodecanol spreads easily when applied to the skin – leaving no visible trace of greasiness.  It is used as a carrier or vehicle and is sometimes a coupling agent for waxes. In this particular case, there are no waxes within the ingredient list for the Kosas Tinted Face Oil.  

In a study published in 2007, examined the lipophilic character of five vehicles (which included octyldodecanol) and eight botanical oils (aloe vera oil, coconut oil, olive oil, grape leaf oil, hazelnut oil, jojoba oil, and safflower oil).  

Lipophilic effect or lipophilicity is a compound’s ability to dissolve in fats, oils, and lipids.  What they discovered was that the most lipophilic effects were observed with octyldodecanol and oleyl alcohol as vehicles coupled with coconut oil, jojoba oil, and safflower oil as botanical oils – suggesting that these specific combinations could be effective dermal permeation enhancers.  

And what do ya know?  There happens to be jojoba oil in this product!

Bottom line:  Octyldodecanol is a carrier or vehicle with lipophilic (fat dissolving) properties coupled with specific botanical oils.  Octyldodecanol was ultimately observed as a potential dermal permeation enhancer.

Avocado oil is an ideal ingredient in skincare formulations intended for dry, dehydrated, damaged and mature skin and in applications intended for the treatment of a number of skincare conditions.  In a study analyzing avocado oil by gas chromatography, presence of oleic fatty acid (47.20%), palmitic (23.66%), linoleic (13.46%) docosadienoic (8.88%), palmitoleic (3.58%), linolenic (1.60%), eicosenoic (1.29%), and myristic acids (0.33%) was found.  The study concluded that used in its natural form or in pharmaceutical formulations for topical use, avocado oil can “promote increased collagen synthesis and decreased numbers of inflammatory cells during the wound-healing process”.

A 1991 study, evaluated the effects of various avocado oils on collagen metabolism in skin whereby growing rats were fed diets containing 10% (w/w) of the tested oils. What was discovered was that rats fed with unrefined avocado oil showed significant increases in soluble collagen content in skin.

Bottom line: Avocado oil is a carrier oil and is often used in collaboration with other essential oils to carry prominent micronutrients and antioxidants deeper into the skin – such as vitamin A, E, and D.

Silica is abundant and makes up 26% of the Earth’s crust by weight.  It is found primarily in rocks, sand, and clay. Sounds a lot like Mica, huh?  In fact, mica is a form of silica! Along with clay (as mentioned before), quartz, emerald, talc, glass, etc.  

In its purest form – silica is unable to exist in its natural state due to its propensity to react with the atmosphere (i.e. oxygen).  Therefore, silica is actually silicon dioxide.  And generally speaking, there are two forms of silica – crystalline and amorphous.  At present, the amorphous form processed synthetically; is traditionally used in cosmetics as an absorbent, anti-caking agent, and suspending agent.

Did you know that it is the third most abundant trace element in the human body?  And silicon has been suggested to improve skin strength and elasticity and pivotal in collagen synthesis?  And it is suggested that a higher silicon content in the hair results in a lower rate of hair loss and increased brightness.  Well, now you do!

In fact, in a study of women aged 40 to 65 with typical signs of photoaging — intake of a bioavailable form of silicon supplements saw a significant improvement after 20 weeks in skin surface characteristics and in its mechanical properties.  The study also observed a significant improvement in the fragility of nails and hair compared to the placebo group after a nine-month period.

Bottom line:  Silica (or silicon) is safe as it is clearly an abundant element within nature AND your body.  And with studies pointing to its positive effects on skin elasticity and improvement in photoaged skin — this is certainly a win-win!

Kaolin (or kaolinite) is a native hydrated aluminum silicate and is often grouped under the term “phyllosilicates” with the CIR panel performing a safety assessment of various silicates and silicate clays.  Kaolin is a clay mineral which primarily functions as an abrasive, absorbent, anticaking agent, bulking agent, and opacifying agent in cosmetic products.  They often are created synthetically or naturally occurring minerals. Clay minerals are often used to remove oils, secretions, toxins, and contaminants from the skin.  In fact, clay minerals can adhere to skin to form a film, which provides protection against external physical and chemical agents.

So how is kaolin beneficial in skincare? 

Well, a 1998 patent describes a cosmetic preparation containing kaolin (either as a mask, lotion, gel or cream) which the proportion of kaolin/spherical particle mixture falls within a range of 0.5 to 10% (Kaolin) by weight of the composition as a whole.  The preparation resulted in a very soft feel on the skin while also having an anti-inflammatory effect when using high kaolin content.  

Clay minerals such as kaolinite may often be used as solar protectors, minimizing skin damage by preventing solar UV from penetrating the skin.  And of course, clay minerals are often used as an absorbent to dissolve or suspend substances such as grease, toxins, bacteria, and viruses!  

Kaolin is accessible in varying colors: red/rose, black, grey, green, yellow, purple, and white.  So we are curious to which form was chosen for this particular formulation.

The CIR panel assessment has deemed kaolin as safe.  However, it is important to remember that if applied topically, any claims to heal must be substantiated based on safety at a minimum in accordance with regulatory agencies,

Bottom line: Kaolin is a naturally occurring clay mineral that functions as an abrasive, absorbent, anticaking agent, bulking agent, and opacifying agent in cosmetic products.  Kaolin has anti-inflammatory properties and may be used in preventing skin damage.

What is mica?  Mica is one of the most abundant and common minerals available within the Earth’s crust – often classified as scrap, flake, or sheet mica.  Historically speaking, mica has been used in a host of various purposes through construction, pharmaceutical, and electrical industries. And in that time, exposure to mica dust in mining, processes, and production have raised many questions about its adverse health effects due to inhalation.  It is often used typically as a colorant – like that in eyeshadows, creams, etc.

One interesting thing to note is that Kosas does not indicate whether the mica used is naturally sourced or synthetically processed.  

A 2008 study determined that a mica substrate coated with iron oxide (which was further coated with colorless titanium dioxide) had a high chroma pearlescent pigment.  In fact, the study assessed that strategic layering of mica + iron oxide + colorless titanium oxide resulted in high chroma pearlescent pigment.

But what is this high chroma business, you ask?  To put it simply, the 2008 study observed that the chroma in aged skin decreased, while youthful skin maintained high chroma levels.  Yet the study did not reference or indicate how it determined chroma levels. And during my search – I was not able to find any linked studies, which correlate chroma levels relative to skin and aging.  So until I find additional information to link that correlation, I am taking it with a grain of salt.

However, since this product includes all three ingredients (mica, iron oxide, AND titanium dioxide) – it would certainly explain its slightly pearlescent sheen when used.  Giving you that lit from within glow!

Bottom line:  Overall, mica is safe and has been historically used for various purposes.  The only concern with this particular form of mica is not necessarily knowing whether it was naturally sourced or synthetic.  However, with trifecta ingredients of mica+iron oxide+titanium dioxide, we know that Kosas was certainly looking at maximizing some sort of pearlescent result; likely attributing to its brightening claims.

Oryza sativa (rice) bran extract (or often called rice hulls) often function as an abrasive and bulking agent in formulations.  It is comprised of proteins, lipids, carbohydrates, mineral ash, and water. The fatty acid composition includes palmitic, stearic, oleic, and linoleic acids.  At low concentrations, rice bran extract contains UV absorbing compounds with no clinical phototoxicity.  The fatty acid composition of rice bran extract includes the following:

• 44.6% Oleic acid
• 36.5% Linoleic acid
• 16.9% Palmitic acid
• 2.0% Stearic acid

A 2011 study of rice bran bioactives entrapped in niosomes was conducted; evaluating the antioxidant capabilities in skincare products from ferulic acid (F), gamma-oryzanol (O) and phytic acid (P).  The study demonstrated the antioxidant activities and skin hydration enhancement of the rice bran bioactive compounds when entrapped in niosomes and incorporated in cream formulations.

In addition, a 2012 study evaluated the anti-aging effects (the skin hydration, elasticity, thickness and roughness, and pigmentation) of the gel and cream containing niosomes entrapped with the rice bran bioactive compounds in human volunteers.  Ultimately, the formulations containing niosomes entrapped with the rice bran bioactive compounds gave superior clinical anti-aging activity which can be applied as a novel skin product.

Bottom line: Rice bran extract functions as an abrasive and bulking agent in formulations; with anti-aging, skin hydration enhancement, and antioxidant properties.

We are no stranger to rosemary and its use in cosmetic products for its antioxidant, anti-inflammatory, and antibacterial capabilities.  We also are familiar with rosemary for its aromatic properties in foods.  But did you know – it has various analgesic and antibacterial properties? More specifically, rosemary oil has been effective against bacterium acne.  In 2007, a study found that there were significant changes in morphology and size of Propionibacterium acnes (P. acnes) in response to rosemary oil treatment.

This sounds promising, right?  Acne sufferers from all over the world rejoice!  

Well before you start singing its praises – a study in 2005 reported a rare case of allergic contact dermatitis due to a cleansing gel containing rosemary extract (0.1% distilled water).  So if you suffer from sensitive skin outbreaks – be forewarned!

But in 2016, a study investigated the combination efficacy of rosemary and grapefruit in decreasing susceptibility to ultraviolet radiation, in addition to the improvement of skin wrinkledness and elasticity.  The study confirmed the photoprotective and anti-aging efficacy with combination use of rosemary and grapefruits.

Bottom line:  Used for its aroma and antibacterial properties for acne treatment.

Tocopherol is the most prevalent form of vitamin E in plant seeds and products derived from corn, sesame seed, sunflower, olive oils, and a plethora of nuts.

Most of the tocopherols are reported to function in cosmetics as antioxidants or skin conditioning agents.  In fact, a 2003 study, evaluated whether the combination of topical vitamin C and E was better for UV protection to the skin than an equivalent concentration of each – alone. The study concluded that each (in their own right) were significant antioxidants in the protection from skin damage. However, the combination of both C and E provided superior synergy against the likes of skin cancer and photo-aging. Further detailed information regarding tocopherol as a major lipid-soluble chain-breaking antioxidant of membranes and an important cellular protectant against oxidative damage was provided in a 2014 CIR safety assessment.

It is also interesting to note that in 1999, a study found that topical vitamin E applied on scars provided no benefit (in 90% of the cases) to the cosmetic outcome of scars after skin surgery.  And it even noticed that 33% of the patients treated, developed contact dermatitis to the vitamin E.

Overall, tocopherol is the predominant form of vitamin E in human and animal tissues, and it has a high bioavailability. The CIR safety assessment recognized that tocopherol has some absorption in the UV range. However, it was noted that according to animal and clinical testing, tocopheryl acetate was not photo-allergenic or phototoxic.

Bottom line: Strong antioxidant capacity. Best if formulated with Vitamin C ingredients but may be a potential for dermatitis.

Meadowfoam oil, itself, has been shown to exhibit exceptional oxidative stability – making it a desirable ingredient often used in cosmetic products. These oils are used in a wide variety of cosmetic products for their skin conditioning, emollient, and moisturizing properties.

When extracted, the seed oil of meadowfoam contains glucolimnanthin, a methoxylated benzylglucosinolate whose degradation products are herbicidal and anti-microbial.

Bottom line:  Meadowfoam oil provides skin conditioning, emollient, and moisturizing properties – exhibiting oxidative stability as well.

Camellia Oleifera is a plant-derived fatty acid tea oil (with origins from China) often functioning as a skin-conditioning, emollient and moisturizing agent in cosmetics.  This ingredient has been identified as safe.

The fatty acid composition of camellia oleifera was studied in 2013 and 2016, with the following %:

• Oleic acid (75.78%~81.39%) an omega-9 fatty acid.
• Linoleic acid (4.85%~10.79%) an omega-6 fatty acid.
• Palmitic acid (7.68%~10.01%)
• Stearic acid (1.46%~2.97%)

In fact, a study published in 2017, characterized the fatty acid profile of camellia oleifera seed oil – looking at cytotoxicity, melanogenesis (the process of melanin production), and antioxidant activity.  The results indicated that camellia oleifera seed oil exhibited the inhibitory activity on melanogenesis and antioxidant activity if up to 3%. In addition, some recent studies have indicated that the extracts of the fruit shell of camellia oleifera have radical-scavenging abilities.

Bottom line:   Plant-derived fatty acid tea oil used as a skin-conditioning agent and emollient – with studies observing the inhibition of melanogenesis.  Camellia oleifera may have antioxidant and anti-radical capabilities.

Rosa canina (rosehip) has long been used for its medicinal properties and often functions as a skin conditioning agent, fragrance ingredient, astringent, anti-acne agent, humectant, and exfoliant in cosmetic products. 

The results of a fatty acid analysis indicated that Rosa canina contains the following most abundant fatty acids: linoleic acid (35.9–54.8%), α-linolenic acid (16.6–26.5%), and oleic acid (14.7–22.1%).  These essential fatty acids are the precursors for omega-3 (linolenic acid and linoleic), 6 (linoleic), and 9 (oleic) which have been shown to in studies to improve skin hydration and elasticity.  And studies have concluded that fatty acids (such as linolenic acid) contained in a majority of these oils create a film on the skin which reduces transepidermal water loss (TEWL), thus contributing to maintaining the correct hydration of the epidermis.   

The rosa canina seeds and shells also contain high amounts of carotenoids (precursors of vitamin A and high amount of vitamin E).  Many studies have pointed to such vitamins to support skin maintenance – with Vitamin A stimulating the cells of the skin, restoring damaged skin cells and therefore, making a brilliant anti-aging ingredient.

With its high composition of fatty acids and antioxidants, this oil has relatively high protection against inflammation and oxidative stress.

Bottom line:   Rosa canina functions as a skin conditioning agent, fragrance ingredient, astringent, anti-acne agent, humectant, and exfoliant in cosmetic products.  Due to its high essential fatty acid content, Vitamin A and Vitamin E content – it often provides anti-inflammatory and antioxidant capabilities. It has also been shown to improve skin hydration and elasticity.

Rubus idaeus (raspberry) seed oil is a fatty acid oil which often functions as a skin-conditioning, emollient, and moisturizing agent.  In fact, its fatty acid composition includes the following with the majority stemming from linoleic and linolenic acids:

• Myristic acid (C14): 0.07%
• Palmitic acid (C16):  2-2.43%
• Stearic acid: 0.9-1%
• Oleic acid:  8-13%
• Linoleic acid:  47-63%
• Linolenic acid:  25-40%
• Arachidic acid:  0.37%

Did you ever think the raspberry fruit would be an ingredient incorporated into your foundation?

Fun fact:  I eat raspberries all summer and all year round (when available). They are dense in nutrients and bioactive composition, so who wouldn’t want that?!  It’s phytochemical/polyphenolic components include anthocyanins and ellagitannin.  

Anthocyanins in red raspberries provide the following:

• Its bright red color.
• Contribute ∼25% of their antioxidant capacity and free-radical scavenging.
• ∼92.1 ± 19.7 mg anthocyanins per 100 g of fresh red raspberry fruit.   
• Possess antimicrobial activity against a wide range of microorganisms.

The other major group of polyphenols is ellagitannins which are categorized as hydrolysable tannins and are esters of hexahydroxydiphenoyl group that consists of either a glucose or quinic acid core.   

What?!

To put it simply, tannins have been shown to help protect against skin tumor promotion induced by UVB radiation.  In fact, some studies have also suggested that tannins play a critical role in the skin barrier as a sweat antigen to reduce itching of patients with atopic dermatitis.

In addition to its phytochemical goodies, red raspberries contain a major aromatic compound known as raspberry ketone (RK).  

Various studies have suggested that RKs provide the following:

• Promoting hair growth and increasing skin elasticity.
• Depigmenting and skin whitening activity. 

Overall, there have been numerous studies evaluating rubus idaeus and its beneficial qualities.  Here are a few notable studies as it relates to the skin:

• A 2015 study evaluated an oil-soluble extract of rubus idaeus to assess cosmetic activities.  Observed results showed that the extract induced the genes responsible for skin hydration and stimulated the expression involved in ceramide production.  The study concluded that rubus idaeus could be used as a hydrating/moisturizing and anti-aging ingredient.
• A 2018 study evaluated the protective effects of rubus idaeus and found that it was effective in preventing UVB induced skin photoaging.
• A 2019 study followed up on evaluating the skin protecting, antioxidant, and anti-inflammatory effects of red raspberry extract (RBE).  The results observed that red RBE administration protected against UVB-induced photodamage and modulated various antioxidant enzymes. RBE also diminished UVB-induced skin inflammation. 

Bottom line: Rubus idaeus (raspberry) seed oil is a fatty acid oil which functions as a skin-conditioning, emollient, and moisturizing agent.  Studies have addressed its beneficial effects (such as skin whitening, skin elasticity, UV protection, and inflammation) based on its phytochemical/polyphenolic composition.

To reiterate what I said earlier regarding mica –  titanium dioxide and iron oxides were likely layered in this formulation to take advantage of the 2008 technique of sandwiching mica+iron oxides+titanium dioxides to create a high chroma pearlescent pigment.

Titanium Dioxide is an inert, semiconducting material, which often exhibits photocatalytic activity in the presence of light.

English, please?

Basically, it’s considered to be a “natural” material which can scatter UV and visible radiation – yet what is also astonishing is that titanium dioxide can also be absorbed at certain levels.  Absorption can often lead to adverse effects such as oxidative stress, cell damage, inflammatory responses, and genotoxic effects. Yikes! However, the effects are strongly mediated and dependent on chemical and physical characteristics of titanium dioxide – such as size, purity, solubility, etc.  Since we as consumers are not privy to exact chemical amount/concentration/size that is generally formulated in products we purchase – this is certainly concerning!

Bottom line:  Overall titanium dioxide has been used in sunscreens since 1952.  However, the FDA has only recently approved its use in sunscreens since 1999.  So at this point, Kosas is likely using these three ingredients of mica+iron oxide+titanium dioxide; with the intention of maximizing some sort of pearlescent results.  Therefore, attributing to its dewy and glowing claims.

CI 77491 (Red iron oxide), CI 77492 (Yellow iron oxide), CI 77499 (Black iron oxide)

Iron oxides are naturally sourced but synthetically processed.  Therefore, most “natural” marketed beauty companies tend to utilize iron oxides in their formulations due to this “naturally” derived colorant source.  Depending on the type of iron oxide, some varieties may have varying trace metals. Due to heavy regulations imposed by the FDA, iron oxides are generally safe as the trace amounts of metal are likely low.

Bottom line:  Synthetically processed but naturally-sourced ingredient used as a colorant or pigment in cosmetics.  Although they do contain trace metals, the amount of allowable iron oxides in products are safe for consumers.