Phytosterols are are plant based sterols like cholesterol that give structure to the plant's cell membrane (the way cholesterol does for our cells). Phytosterols can be converted into Vitamin D and cholecalciferol, both of which have wonderful effects on our skin. You'll find the sterols in the unsaponifiable portion of the oils in fats - the part that won't turn to soap when you add a base to them.
Phytosterols aid in helping our skin's barrier mechanisms recover by penetrating into the skin, rather than occluding the skin, and our body will synthesize some of these phytosterols as it would cholesterol. And it can help cholesterol absorb better when we apply it! As our skin consists of about 25% cholesterol, adding an oil high in phytosterols can go a long way in helping damaged skin recover from the abuses we put it through every day (but don't go claiming you're healing anything!)
If we take a look at the lipids in our stratum corneum, we see they contain about 40% to 50% ceramides, 20% to 25% cholesterol, 15% to 25% fatty acids (those with C16 to C30 chain lengths, with C24 to C28 being the most common), and 5% to 10% cholesterol sulfate. So adding oils with phytosterols
Can phytosterols penetrate our skin? If you take a look at p 225 of Surfactants in Personal Care Products and Decorative Cosmetics, it says that whether or not phytosterols can penetrate our skin has not been "fully studied", meaning that we don't really know much. I've done more searches than I can count, and there's not much out there on this topic.
Having said this, we do know that phytosterols can do some great stuff just being on the surface of our skin. From the abstract of a study, "the sites treated with a formulation containing phytosterols showed an appreciable recovery of barrier function compared to those treated with a vehicle control without soy phytosterols."
So although we don't know if phytosterols can penetrate our skin, we know there are great things they can do being on top of our skin and forming a layer!
Join me tomorrow as we take a look at polyphenols!