Chemistry: Polysaccharides

I need to break for an aside here on the chemistry of polysaccharides as this is coming up more and more as I research our cosmeceuticals.

What are polysaccharides? They are "polymeric carbohydrate structures formed of repeating units joined together by glycosidic bonds" (from Wikipedia). We can find quite basic ones like two monosaccharides like glucose and fructose joined together to make sucrose or D-galactose and D-glucose joined together to make lactose (the picture above and bane of my existence!). We can find more complicated ones like starch, glycogen, cellulose, xanthan gum, guar gum, hyaluronic acid, and so on. We find a lot of polysaccharides in bath and body ingredients, so it's useful to know what they do.

In general, we use ingredients with polysaccharides as healing, soothing, and skin protecting qualities as they reduce irritation and can create a barrier between our skin and the outside world.

Some polysaccharides are considered mucilagenous, meaning they contain mucilage. Mallow, liquorice, and aloe vera all contain mucilage and this gooey stuff can create a film on our skin to protect us while soothing and reducing inflammation. (As Alton Brown calls it in his episode on okra, it's SLIME!) We can make a form of hair gel by soaking flax seed because of this slime and you can find it in chia seeds and carageenan.

Some polysaccharides are starches - like tapicoa, corn, and arrowroot powders, to name a few. These starches can be used alone in products like dusting powders that can help absorb liquids and prevent chafing, or can be included in our products to bind and thicken, like Dry-Flo. In these cases, the polysaccharides offer the skin protecting, soothing, and healing qualities as well as adding thickness (and often increasing that dry feeling) to the products.

We also find polysaccharides like xanthan gum (picture to the left), guar gum, cationic guar gum, and cationic hydroxyethylcellulose (HEC) that will thicken our products and offer that light film forming. These tend to be quite complicated molecules that can create a film on your skin and make things like lotions, shampoos, conditioners, and other water based products thicker.

And some are humectants, like hyaluronic acid (scroll down a bit after clicking). As a note, glycerin is not a polysaccharide, it's a glycerol.

So if you see that an ingredient like beta glucan or sea kelp bioferment contains polysaccharides, you can extrapolate that this will be an ingredient that offers film forming and skin soothing properties. It may or may not add thickness to the product and that's something to investigate when you are considering the viscosity of a product.