Rosehip oil is said to help heal damaged skin, regenerate cells and boost cellular growth.
Meanwhile the Baobab is known as the ‘Tree of Life’ - it can live for thousands of years, with oil extracted from the fruit containing vitamins A, D, E & F.
What makes these oils less suitable for sensitive skin?
Fatty acids in plant oils most typically start off in life attached to glycerol. This is usually in a triglyceride where there’ll be three fatty acids attached to every glycerol, as in the top drawing. In that form, they’re beneficial to the skin and unlikely to cause irritation.
However if that structure breaks down, the fatty acids become free - the bottom diagram - and this can be an issue if you have sensitive skin.
Free oleic acid is able to disrupt and penetrate the skin barrier in a way that isn't possible when part of the larger triglyceride. Great news if you want to deliver actives - it’s actually used in pharmaceuticals for this reason - not so great if your skin is easily irritated.
The Baobab oil above typically has free oleic acid values of 20, and that's before it's considered to have oxidised significantly. Though this is an unusually high free oleic acid value for a plant oil - most will be under 10 - it illustrates that choosing a suitable oil is more complex than looking at the benefits in isolation.
For reference, the free oleic acid values of the oils in our formulas must be 1 or under.
Oils containing significant proportions of Linoleic acid such as the Rosehip oil above are also particularly prone to this triglyceride break down. Adding antioxidants will add to the stability, though once the antioxidants have reached their ‘helping’ limit the oil will start to break down rapidly once more. They also won’t be able to fix any deterioration already occurred.
Some oils are structured so they not only do they have very few free fatty acids to start with, they'll also stay that way long enough to last a product's shelf life.
Meadowfoam seed oil, Jojoba and any part of coconut oil fall into this category. These ultra stable oils are great choices if your skin is prone to irritation. The good news is they'll up the stability to the oils around them, so you can use small amounts of medium stability oils in there too.