The whole picture: Can plant oils be irritating?

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.
Who wouldn’t want those oils, right?  The answer is possibly someone who’s concerned about sensitive skin.

Fatty acids in plant oils most typically start off in life not on their own, but 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. If that structure starts to break down though, the fatty acids become free - the bottom diagram - and this is an issue if you have sensitive skin, as the byproducts of this breaking-down can be irritating. Oils containing significant proportions of Linoleic acid such as the Rosehip oil above, are particularly prone to this.

Meanwhile Free Oleic acid is able disrupt and penetrate the skin barrier in a way that it can’t when it's part of a tryiglyceride. 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.
When measured, the Baobab oil mentioned above typically has free oleic acid values of 20. For reference, the free oleic acid values of the oils in our formulas must be 1 or under to qualify.

The problem is not the fatty acids, it's the instability of the triglyceride structure in those oils. 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 have very little free oleic acid and they also stay in their original state for enough time to last a products' shelf life without shifting significantly. Meadowfoam seed oil, Jojoba and fractionated coconut oil fall into this category. So these are some of the ultra stable oils you'll want to use 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. 

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