Bar Soap: What is all that stuff I can’t pronounce in there?

Updated: Mar 14


When I was growing up, all we had was bar soap.  We were suppose to get it wet before we put in on our skin and make sure we washed if off.  The bacteria, dirt, and excess oils would get washed away.  It’s how we cleaned ourselves.  Somewhere over the next few decades, it became bad.  So what is the verdict I say?  No it is not bad. I prefer bars of soap in the shower because it is easier to use and I get more for my money.  Liquid soaps I tend to go through faster.  Are they bad for you?  No, some may prefer liquid soap.

In a study (1), there was no evidence soap bars spread any infection. So, what is the benefit of bar soap?  I say it depends on what is in the soap.  Many soaps in liquid, and solid form contain detergents. Often drying your skin so you need moisturizer.  Some have moisturizers in their product. Some have chemicals even I, as a nurse, have a hard time pronouncing. It doesn’t necessarily mean the are bad for you. 

What is a soap? 

Well, Merriam Webster says it is “a cleansing and emulsifying agent made usually by action of alkali on fat or fatty acids and consisting essentially of sodium or potassium salts of such acids” (2).  All soaps use a fatty acid, typically a surfactant. Herbal soap, as I like to call it, contains all natural products.  An emulsifier is something that can bind oil and water.

What is typically in herbal soap?

Shea Butter or Double Shea Butter:  The “butter” comes from the fats of the Shea tree. It doesn’t clog your pores, not know for allergic reactions, and used for all skin types.  Shea butter moisturizes your skin without making it oily. Used for it’s antibacterial, antifungal, antioxidant, and anti-inflammatory qualities. The fatty acids are thought to remove excess sebum while moisturizing your skin. Shea butter has triterpenes. This compound is thought to stop the destruction of collagen.

Honey Glycerin:  Glycerin and honey are humectants.  These humectants draw water or moisture from the air into your skin. Glycerin is used to help prevent loss of moisture in your skin.  It also can create a skin barrier to protect your skin.  Glycerin soap may have a lower pH which may hep your skin stay moist.

Lye, in soap making, basically converts ingredients into soap.  The process is called saponification.  Saponification is “the act, process, or result of making soap : conversion into soap” (3).   Lye is sodium hydroxide when making a bar soap (also used as potassium hydroxide). When it’s mixed with oil, water, and other compounds they are all converted into soap.  In the end there is no Lye in the product.

Most essential oils are added.  Depends on what you want.  If you want a scent your favorite one is fine. Common essential oils for skin health are lavender, frankincense, citrus, rose, plantain, calendula, and chamomile. You can pretty much add whatever essential oil is good for use on your skin. 

Don’t remember your chemistry days?  Here is a condensed version:

Propylene glycol:  I hear good and bad about it. What do I know.  They pharmaceutical grade we use is safe under FDA guidelines.  It comes from natural gas.  Why use it?  you need an alcohol base to make soap.  Alcohol is expensive, restricted, or not attainable in large quantities. I would be weary of products not made with pharmaceutical grade glycol.

Sodium stearate:  Found in vegetable oils. It is also found in animal fat.  It’s been the base of soap for thousands of years.  One of the  most common fatty acid salt in today’s soaps.  Why use it?  It is needed to stabilize, harden, and thicken soaps.  Instead of synthetic preservatives it is a natural one.

Stearic Acid: Another saturated fat. Used in soap to clean, remove oil, dirt, and bacteria.

Sodium laurate/sodium lauryl acid/laurie acid (sodium salt of lauric acid):  It’s is used in soap to clean your skin, act as a surfactant, and emulsify your skin.  The surfactant decreases the surface tension between water and in this case your skin.  What does it mean?  If makes foam to help the water take away things like bacteria.  Your lungs actually makes surfactants to clean out your lungs. The purpose of emulsification is to bind the oils and water used to make soap. What should you know?  They are fatty acids which come from plants like coconut, laurel, and palm kernel. Yup, naturally occurring.

Sorbitol is a alcohol from a sugar base.  Why is it used?  for a few reasons.  It helps to hydrate and moisturize your skin. It’s used as a prebiotic.  What is means is it feeds good bacteria on your skin.  Just like your gut has good bacteria. They help your skin stay moist, regulate normal oil production, and fight off free radicals. Where does sorbitol come from? Berries like blackberries, strawberries, raspberries, apples, avocados, and cherries.  Yup, also from natural sources.

Sodium chloride also known as salt. Why add it to soap?  A few good reasons.  Chemically, it makes fatty acid salts in the soap.  In English, it helps stop the soap from drying out your skin too much. It also helps to exfoliate your skin. Yup. also from natural sources.

Silica (Silicon dioxide) is a mineral commonly found in quartz and sand. It’s one of the most common elements. You can find versions of it in toothpaste.  It’s is used in soap making to stop something called soap sweat or also known as glycerin dew. Remember how I said glycerin is a humectant.  Great to put on your skin to draw moisture.  The down side. It will draw moisture to the soap.  Silica helps to stop  the moisture on the soap. Also natural.

Titanium dioxide is a natural element used to lighten soap and make them look “prettier”.  It is also in most sunscreen.  It is used to protect against UV light.

Pentasodium pentetate is the salt from Pentetic Acid (4) .  Used as something called a chelating agent.  What it does is prevent metal ions from water from forming soap scum. 

Tetrasodium etidronate another chelating agent (5).  Also known as a water softener. I have seen sites calling it cancer causing.  In large doses or not taken as directed it is a corrosive and irritant (6).

Methylisothiazolone is an organic compound used in “green” cleaning products and personal care products like soap.    It is an organic preservative or antimicrobial.  It is determined by the Cosmetic Ingredient Review to be safe in soap and skin care products (7).  If not used as directed can cause contact dermatitis and allergic reactions (8).

Magnesium chloride is added to soap to help with hard water.  You can find it in sea water.  It help with foaming.  Why is foaming in a soap important? Remember the word surfactant.  It helps the water take away things like bacteria, sebum (oil on your skin), and dirt when washed away.

Magnesium nitrate is a naturally occurring mineral. It is often found in goat’s milk products.

Most of the ingredients which are chemical compounds and hard to pronounce are found in soap bases like glycerin and goat’s milk.  They are most often naturally occurring, derived from plants, animals, or minerals. They each have their role.  What is important to know before you use these products or any other products remain the same.  Do you have allergies and make sure your rinse. Soaps and cosmetics are governed by the FDA or Consumer Product Safety Commission.  I go to the best source. Places like Pubmed, NIH, and Pubchem.  These are what are called information clearing houses.  Meaning studies, material safety data sheets (MSDS) are found. I see some of these compounds being called cancer causing and toxic.  Well if you drink liquid soap no good will ever come of it.  The following compounds are not toxic if used as directed.  They have no cancer causing agents and have a purpose in soap.  Now, they are used on your skin.  So if you have allergies or don’t use as directed be wary.

References:

  1.  Heinze, J. E., & Yackovich, F. (1988). Washing with contaminated bar soap is unlikely to transfer bacteria. Epidemiology and infection, 101(1), 135–142. https://doi.org/10.1017/s0950268800029290

  2. Saponification | Definition of Saponification by Merriam-Webster (merriam-webster.com)

  3. Soap | Definition of Soap by Merriam-Webster (merriam-webster.com)

  4. Benes DM, Burnett CL. Final report on the safety assessment of pentasodium pentetate and pentetic acid as used in cosmetics. Int J Toxicol. 2008;27 Suppl 2:71-92. doi: 10.1080/10915810802244546. PMID: 18830865.

  5. National Center for Biotechnology Information (2021). PubChem Compound Summary for CID 19629. Retrieved February 15, 2021 from https://pubchem.ncbi.nlm.nih.gov/compound/Tetrasodium-etidronate.

  6. National Center for Biotechnology Information (2021). PubChem Compound Summary for CID 3305, Etidronic acid. Retrieved February 15, 2021 from https://pubchem.ncbi.nlm.nih.gov/compound/Etidronic-acid.

  7. https://www.researchgate.net/publication/51444336_Final_Report_of_the_Safety_Assessment_of_Methylisothiazolinone

  8. National Center for Biotechnology Information (2021). PubChem Compound Summary for CID 57269290, Methylisothiazolone. Retrieved February 15, 2021 from https://pubchem.ncbi.nlm.nih.gov/compound/Methylisothiazolone.lulusthymeandessentials.com

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