This post is the result of a burning question I had about squalane’s effectiveness as a menstruum. It was clear from my own experimentation that squalane was not as effective as regular fatty oils at capturing certain plant constituents — as evidenced by the color of the infused oil. Try as I might, squalane herbal infusions rarely had anywhere near the vibrance of color I would get from my other infusions using oils like olive oil or tallow. Sometimes they stubbornly remained crystal clear, begging the question(s):
Is the squalane actually extracting anything? Can it be infused with plant constituents for use in skincare formulations or am I wasting my time?
Inquiring minds want to know!
Why use squalane in the first place?
When I asked this question in various herbalism and DIY skincare forums, I almost always got some variation of the same response: Why do you want to infuse squalane anyway? Why not just use a regular carrier oil like olive or almond?
I’m interested in squalane (with an A) because of its strong compatibility to squalene (with an E), a natural component of our skin’s surface lipids. Varying slightly by source, squalene makes up approximately 10-16% of healthy human sebum, along with cholesterol and sterol esters (2-4%), wax esters (20-30%) and triglycerides and fatty acids (50-60%). Squalane (along with jojoba oil and tallow) is an important part of my sebum mimic formula that attempts to approximate the composition of healthy skin lipids.
Squalane is not technically an oil at all. It’s a non-polar, liquid hydrocarbon that doesn’t contain any fatty acids or glycerol, which are the main components of traditional oils. Squalane is often included in skincare products as a lightweight, highly absorbent emollient. It’s colorless, odorless and non-greasy, and is used widely in the cosmetic industry due to its biocompatibility with human skin.
Interestingly, it appears that skincare products containing squalane may also be labeled “oil free.” 🧐
Squalene vs squalane
SqualEne (with an E) is a naturally occurring lipid synthesized by the liver and secreted by the sebaceous glands in humans and other animals. It’s found in particularly large quantities in shark liver oil, which was once the primary source of commercial squalene. Due to ethical and sustainability considerations, most squalene used in cosmetic and personal care products nowadays is going to be derived from plant sources such as olives, wheat germ, amaranth or rice bran.
The natural form of SqualEne has six unsaturated double bonds in its chemical structure. Double bonds are more vulnerable to oxidation and degradation because they have more potential reactive sites than single bonds. The double bonds can react with oxygen, heat or light to form free radicals, which damage the skin and cause the oil to become rancid extremely quickly, making it a less than ideal skincare ingredient.
SqualAne (with an A) is a hydrogenated form of squalene in which hydrogen atoms have been added to the double bonds of the unsaturated hydrocarbon molecule, converting them into single bonds. By hydrogenating squalEne to create 100% saturated squalAne, those vulnerable double bonds are eliminated and the resulting oil becomes much more stable and resistant to oxidation.
So if squalEne is a natural part of our skin’s surface lipids, does that mean we’re all walking around with rancid oil on our skin?
Nope!
Our skin’s natural squalene is constantly being replenished, replacing old squalene with new. Our sebum also contains other lipids such as triglycerides, wax esters and cholesterol esters, which can act as stabilizing agents and help to prevent squalene from oxidizing and going rancid. We also produce natural antioxidants such as vitamin E, ubiquinone and glutathione, all of which help to protect against oxidative damage.
But that’s not all!
Unlike hydrogenated squalane, natural squalene has excellent antioxidant capabilities as a free radical scavenger. Squalene uses its susceptibility to oxidation to our advantage, serving as a “sacrificial” antioxidant. When squalene encounters free radicals, it donates electrons to neutralize them, sacrificing itself in the process. In this way, squalene serves an important role as a natural defense against oxidative damage from UV light and other environmental stressors.
So while isolated squalene in a bottle is vulnerable to oxidation and rancidity, the squalene produced by our skin is well-protected and, in turn, helps to protect us!
Ain’t nature grand? ♥
But... aren't hydrogenated oils bad for you?
We all know by now that hydrogenated oils can have negative health effects when consumed due to the formation of trans fats, which increase the risk of heart disease and many other health issues. But what about topical hydrogenated oils used on the skin?
While there’s a theoretical possibility that small amounts of hydrogenated oils could be absorbed into the bloodstream through the skin, the available evidence suggests that this is unlikely to occur in significant amounts via topical application.
But isn’t skin our body’s largest organ? Yep it is! But it’s also a barrier designed to protect the body from external harm. It prevents the absorption of larger molecules into the bloodstream, selectively allowing some substances to pass through while preventing others from penetrating too deeply. The molecular size of a substance play a significant role in determining whether it can penetrate the skin barrier and reach the bloodstream.
So when applied topically, most skincare ingredients (including oils) are absorbed into the outermost layers of the skin where they can provide benefits such as moisturizing and improved skin barrier function.
Partially vs fully hydrogenated
Another factor is the difference between partially hydrogenated and fully hydrogenated fats.
Partially hydrogenated oils are created by adding hydrogen to liquid oils, which creates solid form that is more stable and has a longer shelf life. As the name suggests, the partial hydrogenation process is stopped before all of the double bonds in the oil are completely saturated with hydrogen, resulting in a partially hydrogenated oil that contains both saturated and unsaturated fatty acids. Some of these remaining double bonds may be converted into trans double bonds, where the carbon chains end up on opposite sides of the double bond instead of the same side, resulting in an artificial trans fat.
Fully hydrogenated oils, on the other hand, are created by fully saturating the oil with hydrogen, which results in a 100% saturated oil that contains no trans fats. Full hydrogenation converts all of the double bonds to single bonds, resulting in a fully saturated fatty acid. Since there are no remaining double bonds, there is no opportunity for any trans configurations to form.
Squalane is an example of a fully hydrogenated oil. Unlike most hydrogenated oils, though, squalane is not solid at room temperature because of its unusually low melting point (23.36°F).
TLDR: While I wouldn’t recommend consuming either type of artificially hydrogenated oil, my read of the available info is that squalane in topical applications is probably fine.
Infusing squalane
Squalane is a single molecule (C30H62) with a lower molecular weight and viscosity than most fatty oils, which limits its ability to solubilize and extract certain constituents. Non-polar compounds with high molecular weights may be more soluble in fatty oils such as olive or coconut oil, which contain a mixture of triglycerides and other lipids that aid in the extraction of oil soluble plant constituents.
Some example of higher molecular weight constituents include certain carotenoids like beta-carotene; some terpenes such as hypericin in St. John’s wort; and most phytosterols such as beta-sitosterol in comfrey or stigmasterol in red clover.
Resins like those found in benzoin are also typically higher molecular weight compounds. Here’s a photo of a benzoin oil infusion I tried to do using squalane. As you can see in the image, what resin that was extracted did not dissolve and remains separated, floating in the squalane and settled at the bottom of the jar:
Not a total failure, but not quite the benzoin-infused squalane I was hoping for either. Most of benzoin’s lovely vanilla-y fragrance is bound up in that undissolved resin.
Squalane may still be a useful solvent for less complex compounds and ones with lower molecular weights such as flavonoids and carotenoids. Squalane’s effectiveness as a solvent depends on the specific plant constituents you’re trying to harness. Websites like Dr. Duke’s Phytochemical and Ethnobotanical Databases are indispensable resources for sorting out which constituents a certain plant contains.
There are a few things that can be done to enhance the ability of squalane to extract plant constituents. Don’t simply pour squalane over your herb and hope for the best. It likely will not work.
One approach is to use an alcohol intermediary extraction in which a small amount of high-proof ethanol is added to the herb before infusing in squalane. The ethanol can help to break down cell walls and dissolve certain constituents that are not easily extracted by squalane alone.
Heat also helps to facilitate the extraction process. Applying gentle heat can help to break down cell walls and increase the solubility of certain constituents in the squalane without harming the oil or degrading the delicate phytochemicals.
Generally, any plant that contains oil soluble constituents may be extracted (at least in part) by squalane, you just need to be mindful of which constituents are important to your formulation.
Have you experimented with infused squalane before? Tell us about it in the comments! ♥
