Surfactants are used in everything around us, not only in detergents and shampoos but also in cosmetic products. Nowadays, many people know that surfactants can be toxic for the skin and try not to use them as much as possible. The dangers of surfactants have become widely known and there are more and more surfactant-free cosmetics.
When considering skin health, surfactants are indeed the ingredients we should avoid as they are the great enemy of the skin microbiome.
However, it is also true that surfactants have certain functions such as removing dirt and reducing friction. What is important here is to understand the characteristics of each surfactant and deal with them efficiently.
Today we will introduce a wide range of knowledge about surfactants, including their benefits, the difference between natural and synthetic surfactants, their effects on the microbiome, and the detailed types and correct usage.
- Why are surfactants in cosmetics?
- Natural and synthetic surfactants
- The difference between slightly acidic and slightly alkaline
- Why are surfactants the enemy of the microbiome?
- Types and strengths of synthetic surfactants
- How to deal with surfactants
Why are surfactants in cosmetics?
We are sure most of you know that water and oil do not mix. And surfactants are the substances that blend these two mutually repelling substances.
Surfactants have both water-miscible (hydrophilic group) and oil-miscible (lipophilic group) parts in their molecules, and they can change the interface between water and oil.
They are used mainly in washing materials like soap, detergents, and cleansers. Since we can't remove oil stains or makeup dirt with water alone, we need surfactants. We even can say almost all washing materials contain surfactants.
However, many cosmetics (not facewashes) contain surfactants, too. Can you guess why? To answer this question, we need to learn about the other functions of surfactants.
The two main reasons for surfactants are in cosmetics are:
To emulsify water and oil to maintain product stability. Especially in products often used for long periods. For example, emulsions, liquid foundations, sunscreens, etc.
2) Penetration-enhancing action
To increase skin penetration and make it easier for beauty ingredients in serums and lotions to the sebum membrane and stratum corneum.
As mentioned here, surfactants have the definite function of stabilizing cosmetics and promoting the penetration of beauty ingredients.
However, surfactants can be harmful to the skin depending on how they are used. To minimize this danger, let us explain a little more about the properties of surfactants.
Natural and synthetic surfactants
First, to know the characteristics of surfactants and properly interact with them, we need to understand the difference between "natural" and "synthetic" surfactants.
When you hear just these two words, you may imagine that the "natural" one is gentler to the skin than "synthetic." However, whether natural or synthetic, surfactants can damage the skin depending on how they are used.
Below is an introduction to each of them.
Natural surfactants: Ingredients that originally exist in nature. Including saponin, lecithin, peptides, etc.
Synthetic surfactants: Artificially synthesized ingredients. Including sodium lauryl sulfate, sodium Laureth sulfate, etc.
Most cosmetics and detergents contain synthetic surfactants. Synthetic surfactants are increasingly used because they can be mass-produced inexpensively and have excellent cleansing effects.
Soap is also a type of surfactant. Although soap appears harmless, it is unmistakably a surfactant, with strong degreasing power and often be the alkaline side, which even can lead to skin problems.
The difference between slightly acidic and slightly alkaline
Have you ever heard the term "slightly acidic soap?" Many people seem to know that slightly acidic products are gentler on the skin. But do you know why?
Healthy skin pH is slightly acidic. But if there is a skin problem such as atopic dermatitis, it leans toward the alkaline side.
If the skin is healthy, washing with alkaline soap does not cause a major problem because the pH can return to normal afterward.
But if the skin has some trouble and is inclined to alkalinity, the barrier function becomes weakened, and skin problems are more likely to occur. Therefore, we recommend washing your face with slightly acidic products.
And Epidermal staphylococci, "good microbiome for skin," and Cutibacterium acne have the role of maintaining the skin pH at a slightly acidic by producing fatty acids.
So, it is important to avoid over-washing and protect the "good microbiome for skin" to get healthy skin.
Why are surfactants the enemy of the microbiome?
Recent studies have shown that surfactants cause various types of damage to the skin. Here, we will explain in detail how surfactants affect the microbiome.
1) Destroy the home of "good microbiome for skin".
The stratum corneum is the outermost layer of the epidermis. This layer serves as a barrier to prevent the evaporation of moisture from the skin and to protect it from external irritants. The microbiome lives on the surface of the stratum corneum and in the spaces between corneocytes.
"Good microbiome for skin" has excellent power to maintain the skin balanced, such as moisturizing the skin with ingredients produced by decomposing sebum and maintaining the pH of the skin at a low acid level by releasing fatty acids.
Although the microbiome, in another word, "bacteria" may sound bad, it is known that the skin condition is better if a certain amount of "good microbiome for skin" lives in the skin.
Ingredients that are incompatible with "good microbiome for skin" include alcohol, preservatives, and surfactants.
Surfactants destroy the stratum corneum, which is the home of "good microbiome for skin."
For example, beauty serums and introductory solutions that penetrate the skin often contain surfactants to increase the penetration of beauty ingredients, but in the long run, this may damage the home of the good microbiome for skin, resulting in a decrease in the number of them.
What is the “good microbiome for skin”? A microbiome expert explains the skincare effects that are as good as cosmetics.keyword: good microbiome for skin
2) It can be a limiting factor for the microbiome because of its strong degreasing power.
Surfactants float oil and remove dirt and makeup. At the same time, however, they also wash away sebum, which is necessary for the skin, causing skin dryness.
This also has a negative impact on the "good microbiome for skin" as they feed on sebum to increase in number. If sebum is completely eliminated by face washes and soaps containing surfactants, there will be no food source and the environment becomes uninhabitable for "good microbiome for skin."
Therefore, it is important not to wash too much and to leave a moderate amount of sebum to nurture the skin microbiome.
3) Some surfactants may kill bacteria.
Some types of surfactants have bactericidal effects in addition to cleaning and emulsifying effects.
Cationic surfactants are charged with positive ions and exhibit excellent bactericidal effects. For example, benzalkonium chloride, a typical bactericidal ingredient also used in disinfectants, is a type of cationic surfactant. Its bactericidal action means that it may kill not only the bad bacteria but also the good microbiome.
It is important to have a good balance of both good and bad bacteria to maintain beautiful skin.
From this point of view, we recommend using as few preservatives as possible as well as surfactants for your skin.
Types and strengths of synthetic surfactants
There are many different types of surfactants with varying strengths and we don't have to avoid all kinds of surfactants.
Here we will introduce what kind of surfactants are gentle to the skin and cause minimal damage to the microbiome, along with each type and cleaning strength.
Surfactants that are electrically charged tend to irritate the skin. When dissolved in water, cationic surfactants have a positive electric charge and are excellent in lubricating, softening, and sterilizing effects.
Because of this character, they are mainly used in hair treatments and fabric softeners, but some types are also used as disinfectants and antiseptics.
They have the strongest bactericidal effect and can be irritating to the skin. Since the human skin surface is covered with a negatively charged biological membrane, cationic surfactants with opposite properties are particularly prone to irritate.
Examples: Benzalkonium chloride, Behentrimonium Chloride
Anionic surfactants are negatively charged when dissolved in water and have excellent cleaning and bubbling properties. They are the surfactants that we are most frequently exposed to in our daily lives.
They are used as the main ingredient in soaps, detergents, shampoos, and other products because of their strong cleaning power and good foaming properties.
Compared to cationic surfactants, anionic surfactants’ skin irritation is weaker, but the strength of the degreasing power depends on the type. For example, amino acid-based and carboxylic acid-based are gentler for people with sensitive or dry skin.
Examples: Sodium lauryl sulfate, Sodium Laureth Sulfate, Sodium C14-16 Olefin Sulfonate
Amphoteric ionic surfactants
This surfactant has both negative and positive properties but is electrically neutralized, resulting in its cleansing power being relatively mild. It has low skin irritancy, and its properties change depending on the pH, being a fabric softener in acidic conditions and a detergent in alkaline conditions.
Because of this, amphoteric ionic surfactants are often used as an ingredient in baby shampoos. Also, they are often used to adjust the detergency and skin irritation of other surfactants instead of being used alone.
Examples: Cocamidopropyl betaine, Lauramidopropyl betaine, Sodium cocoamphoacetate, Lecithin
They are the only type of surfactant that is not electrically conductive and has little toxicity or skin irritation. They have emulsifying, solubilizing, cleaning, and bubbling effects, but their cleaning power is weak, so they are mostly used in combination with other surfactants when formulated for cleaning purposes.
They are mainly used as an emulsifier and cleaning aid in cosmetics and food additives. Because of their mild skin irritation, they are often used in skincare and makeup products.
Examples: Alkyl glucoside, Lauramide DEA, PEG-60 Hydrogenated Castor Oil, Laureth 4,7,9,21,23
How to deal with surfactants
As explained above, the number and kinds of surfactants make us overwhelmed. Now, let us consider how we can deal with them in our daily lives.
1) Select surfactants according to skin type and purpose
Surfactants in commercial products are certified for safety. However, they can cause skin problems for people with sensitive skin, atopic or dry skin.
Also, even for those with healthy skin, continued use of surfactants can inhibit the home of the microbiome, causing an imbalance that can lead to skin problems.
So, we recommend you start with changing the body soap or shampoo you use every day to a gentler surfactant.
For example, you can choose an amino acid-based or carboxylic acid-based surfactant, or a cationic treatment with a nonionic surfactant that is less damaging to the skin.
From the wide variety of options available, it can be fun to find one that best suits your needs.
2) Keep surfactant-based cosmetics to a minimum.
The use of surfactants is unavoidable for washing. The point is to remove unnecessary dirt" but not to remove too much sebum.
It is not recommended if surfactants are contained in items that are in contact with the skin for long periods, such as foundations and sunscreens. Also, if your lotion or introductory serum contains surfactants in your cosmetics, we recommend changing to something else. Since these are the first items that come into contact with the skin after cleansing, they may cause excessive irritation.
In particular, if you suffer from rough skin or are concerned about dry skin, check whether there are surfactants in your cosmetics.
These days, there are more and more surfactant-free cosmetics available. Be sure to check ingredient labels when purchasing cosmetic products.
3) Find the right balance
Excessive avoidance of surfactants can also cause skin problems.
For example, if a person who secretes a lot of sebum uses a surfactant with weak detergent power, the remaining sebum may end up causing skin problems.
On the other hand, using a large amount of a skin-friendly surfactant, or scrubbing too hard, is also not a good idea. Friction can be more of a burden on the skin than surfactants.
Choose the right surfactants depending on your makeup intensity.
4)Not to rely too much on surfactants.
Many people may rely on the cleaning power of surfactants to remove intense makeup or to remove sebum and refresh the skin.
This may be fine if there are no skin problems, but if you experience some skin problems or dryness of the skin, it is important to review the cause of them in the first place.
For example, how about switching to mascara that can be removed only with hot water, or to soap-removing cosmetics?
Makeup that does not require strong cleansing power can also decrease the damage when you remove it.
5) Change your diet to control the amount of sebum
If you have a problem with high sebum secretion, aim not only to remove it with surfactants but also to control sebum secretion at the same time.
Dietary habits also have things to do with excessive sebum secretion. Sebum secretion is necessary for the skin barrier, but excess of them can cause skin problems.
In particular, be careful with sweet foods, refined white sugar, and other foods that raise blood sugar levels quickly (high GI foods) since sebum is secreted in large amounts at the time when blood glucose levels spike. (References)
It's a good idea to care from the inside of the body too if you want to get balanced and healthy skin!
Phew! We've learned a lot about surfactants today.
The most important thing here is to find a way to deal with them by getting to know them. There is no need to be overly fearful. Maybe, this is the same as when we deal with other people. Keep a reasonable distance with surfactants and get beautiful, healthy, trouble-free skin!
・Robyn Smith, A pilot study to determine the short-term effects of a low glycemic load diet on hormonal markers of acne: a nonrandomized, parallel, controlled feeding trial, Mol Nutr Food Res. 2008 Jun;52(6):718-26.