Wednesday, April 22, 2015

Fatty acids: What's up with them? Part three

Let's continue our look at Erika's question about fatty acids from this post...

Then, I look at other fatty acids in each of the oils and additional confusion sets in, with the function, or mechanism of other fatty acids contained in those oils.

Another example, coconut oil. It contains a lot of lauric acid (47.5%) But, so what? (not to sound cheeky) What does that mean other than the fact that lauric acid is a saturated fatty acid, C12, so it's a medium chain fatty acid, no double bonds, which offers a long shelf life. What is the effect, or benefit of lauric acid? What can I expect from the lauric acid in coconut oil? 

And, coconut oil also contains unsaturated fats with "18.1% myristic acid (C14), 8.8% palmitic acid (C16), and a titch of stearic, oleic, linoleic, and arachidic acids. Because of this saturation, this is a very long lasting oil." C16 palmitic acid and C18 stearic acid are also saturated fatty acids, as well as myristic acid (C14)

Stearic acid - helps with moisture retention, flexibility of skin and skin repair (saturated C18), it also provides thickening properties - how? why? is it because it's a saturated fat?

And myristic acid (C14), which is much like stearic acid, but it's considered a penetration enhancer - why is this considered a penetration enhancer when it's similar to stearic acid which works as a co-emulsifier and thickener.

GLA - helps with inflamed skin, and helps restore barrier function (polyunsaturated - omega 6 - C18:3)

Sigh.

I'm not trying to be a chemist. I just would like some basic understanding so that when I look at the fatty acid profile of an oil I can say, oh, hey, this has lots of myristic acid, so I can expect __________ from this oil because myristic acid does __________________ by way of __________________ (in an easy to understand way) :-)

If you're just joining us, I suggest reading part one and part two of this post from earlier this week?

All fatty acids are going to offer moisturizing to our skin as they are found in oils, which are inherently moisturizing. Having said this, there isn't a lot of really great information on what fatty acids other than linoleic (and its relatives) or oleic acid. I couldn't find much on stearic, palmitic, myrisitc, or lauric acids.

What does stearic acid offer to our skin? Stearic acid is a saturated fatty acid that has reported anti-viral and anti-inflammatory properties, as well as thickening properties. Adding stearic acid or a butter containing it will be thicker than those without. This thickening power is thanks to the structure of the molecule in that it lies straight, meaning that more molecules can pack into a smaller space, making it thicker. (Check out this post...) As well, it can make our skin feel slightly colder than using a product without it.

What does lauric acid offer to our skin? Lauric acid is a saturated fatty acid that has reported anti-microbial properties that could be used as treatment for acne issues. It will help to thicken the products we make containing it.

What does myristic acid offer to our skin? It is a saturated fatty acid that will help to thicken the products we make containing it and it will offer moisturizing to our skin. I could not find anything indicating it was a penetration enhancer.

What does palmitic acid offer to our skin? It is a saturated fatty acid that will help to thicken the products we making containing it and will offer moisturizing to our skin.

I'm afraid I can't find much on lauric, myristic, or palmitic acid on the 'net or in my textbooks. I am presenting what I have found. Please send me anything you might have from reputable sources about these acids if you have them! I'd be thrilled to read them! 

When it comes to your sample sentence above, you could say - oh, hey, this has lots of linoleic acid, so I can expect it to help restore barrier function and can reduce transepidermal water loss because it is a fatty acid found in our skin and it can reduce inflammation because it helps produce eicosanoids that play a critical role in inflammation and immune system responses in our skin and because it's converted into GLA in our skin. I also think it'll be quite liquid because of the large quantity of cis bonded linoleic fatty acids.

You could say that stearic acid will offer moisturizing because it's found in this or that butter, that it will thicken the product in which we use it thanks to the structure of its molecule and high melting point.

I'm afraid I can't offer much in the way of information on the other fatty acids as there just isn't any great information out there.

References:
Linus Pauling Institute
Anti-microbial property of lauric acid against Propionibacterium acnes
Topical application of docanosol or stearic acid containing creams reduces the severity of phenol wounds in mice

3 comments:

Melissa Kern said...

Hi Susan! :)
I have just found your site after searching for info for my Beauty Therapy assignment on cosmetic chemistry. I have a feeling I'm going to be coming back here a lot now!
I found a little extra information on each of these fatty acids and thought I would share it in case it helps anyone.

Stearic Acid - an emulsifier and thickening agent found in many vegetable fats. May cause allergic reactions in people with sensitive skin and is considered somewhat comedogenic.

Palmitic Acid - one of the skin's major fatty acids produced by the sebaceous glands. In cosmetic formulations, it is used as a formula texturiser.

Myristic Acid - a surfactant and cleansing agent. Although some sources site it as having no irritation potential, they do indicate comedogenicity potential.

Lauric Acid - foaming properties. It is a mild irritant but not a sensitizer, and some sources site it as comedogenic.

All the info is from Milady Skin Care and Cosmetic Ingredients Dictionary 4th Edition by M. Varinia Michalun and Joseph C. Dinardo. In the book there is a little more information for each one but I didn't think it was relevant as it was mainly to do with where it was found our what it is used in.
Hope this helps!
Mel

patrick said...

Hello Susan, this post and some other poking around I have done recently on leather care prompted this question: What is the difference between moisture from water in our skin vs. oils? In leather care the two have to be in balance for it to be a strong flexible material and I would assume it is the same in human skin. Do you know of a good ratio for the skin, or ways of maintaining that ratio? Many people seem to be slathering oils on their face to "moisturize" but can't too much oil and not enough water have negative effects? It sure does in leather experiments (Stambolov, T., H.A.B. van Soest and P.B. Hallebeek. "Conservation of Leather." Studies in Conservation 29 (1984): 21-31.)

Susan Barclay-Nichols said...

Hi Patrick. I've written a post on this topic - what's the difference between moisturizing and hydrating? - and you can check out the posts in the skin chemistry section of the blog. In short, we want to use both water and oil on our skin to help hydrate and moisturize as you mention. We want to have 10% to 20% water in our skin, and we use the oils to prevent trans epidermal water loss!