Saturday, July 31, 2010

The chemistry of our nails: Lecithin

So what's the deal with lecithin? Lecithin is a yellowy substance filled to the brim with various phospholipids or phosphatides, generally extract from eggs or soy beans, although its found in all plants and animals.

The soy and the egg lecithin do differ a little. The soy has a fatty acid profile of 20% palmitic acid (C16), 4.3% stearic acid (C18), 11.4% linoleic acid (C18:1), 56.6% linolenic acid (C18:2), and about 7% linolenic acid (C18:3). The egg lecithin contains 30% palmitic acid (C16), 15.9% stearic acid (C18), 26.4% oleic acid (C18:1), 16.2% linoleic acid (C18:2), and no linolenic acid. It does, however, contain arachadonic acid at about 6%. Both of these contain little to no Vitamin E, but they contain B vitamins (choline, Vitamin B8), and they contain 60% to 70% phospholipids (made up of the fatty acids listed above). Most of what we find on our suppliers' shelves is the soy version of lecithin, but if you're vegan or have any restrictions on your diet, ask before buying.

Choline has been shown to increase skin hydration, so it can act as a humectant to bring water our skin. In one study, the application of lecithin to skin increased water retention by 40% and it lasted about 2.5 hours! Another ingredient in lecithin - inositol - has been shown to decrease trans-epidermal water loss in  animal studies. It's also been shown to increase moisture retention in our hair. And it's an anti-oxidant - it's three great things in one!

Lecithin is considered a great moisturizer with those high levels of oleic and linoleic acids, which will moisturize and help restore a damaged skin barrier. The stearic acid is also very moisturizing!

Lecithin can act as an anti-oxidant in our products, scavenging to prevent lipolytic rancidity at 0.01% to 0.25%. It can help boost the efficacy of Vitamin E and Vitamin C as anti-oxidants (science isn't really sure why this is...)

Lecithin can be used in myriad ways in our formulating. It can be used in balms to act as a moisturizer, emollient, and protector. It can be used as a co-emulsifier in the HLB system (check with your supplier as it could have an HLB of 4 or 7, depending on how it is processed). It can be used wet oxides for mineral make-up if you want to press your eye shadows!

When it comes to nail care, lecithin is a Viking! It works well at low levels to moisturize our nails and help return some of those phosopholipids to dry and brittle nails!

One of the down sides of lecithin can be the smell. It can get a fishy odour at around 49˚C and will smoke at 70˚C, so you want to melt this stuff in a double boiler, not the microwave where you can't judge the temperature. You only want to heat lecithin slightly - never ever take it to the heat and hold stage or you'll get a horrible stench, so add it as you're about to take your oil phase out of the double boiler and mix it well.

The lecithin I purchased from Aquarius is a sticky brown liquid that I can add at room temperature to various anhydrous products. (It's really inexpensive - $4.00 for 250 ml or 8 ounces). And you can include it in any of your products as up to 10% as an oil. (You can use more, but it does have kind of earthy scent that might annoy some people). It is oil soluble, so you won't be putting this into any of your toners or skin refreshers!

Join me tomorrow for fun with lanolin!

6 comments:

p said...

Thank you for this awesome post!! I've heated and held (holded?!) lecithin before and have smelled the fishiness, but I just assumed the stink was unavoidable if you heat lecithin at all! Such valuable information. Why does it go all stinky, anyway? Are the oils oxidizing? Something else?

I've got another lecithin-related question for you. I've read it mentioned on the internets that avocado oil "contains lecithin." I don't even know what that's supposed to mean! Does this statement make sense to you, and if so is it true?

Anonymous said...

Does it matter which lecithin (HLB 4 or 7) you use if you're not using it for emulsification purposes? Thanks!

Brandi Yates said...

I accidentally bought powdered lecithin. Are there any recipes using it this way?

Susan Barclay-Nichols said...

Hi Brandi. I haven't used it that way. I suggest one of two things - get in touch with your supplier and ask for a few formulations, and search! I found a few interesting links. Please note that listing them here implies nothing as I've only skimmed the recipes and can't guarantee anything will work.

Mountain Rose Herbs
My Home Made Beauty

Georgina said...

Hi Susan,

I have been making hair pomade using anhydrous ingredients only – predominately wax, oils, and a little clay. I am wondering if I add a little lecithin to the mixture will it make the pomade easier to wash out, because of the emulsifying properties?

Thanks so much,
Georgina

p.s. AMAZING BLOG!

Sandee Lynn said...

I take 2 lecithen capsules 1000 mg each. daily and I have noticed my fingernails stronger and longer, I can't wait to see what my cholesterol level will be as I heard it's good for that as well.