Spurred by a comment from Mike that argan oil has no substantive advantages over much less expensive rosehip seed oil, I determined to find out more. This notion took me on a rollercoaster of research highs and lows. I am pleased to say that I ended with a high (and an order for a bottle of rosehip seed oil).
Rosehips are the Sun Gods of alternative medicine zealots. They make wrinkles go away completely. They miraculously fade sun spots and stretch marks. Wounds and scars disappear without trace. Most of this is anecdotal and without any clinical evidence to back it up. That's because it is grown only in the Andes and is well-kept Chilean secret. Right.
There are a couple of (frequently quoted) studies dating back to the 1980s. A Chilean evaluated the the oil in the skin regeneration process. And in 1988, two doctors published their own findings in a paper called "Contributions to Identification and Application of Active Components Contained in Rosa Affinis Rubiginosa". These studies suggested that rosehip worked. The next question was how.
Retinyl or retinoic acid was discovered by a researcher looking for a quick drying varnish oil [Pareja; Siber Hegner]. Consequently (and despite the lack of any other evidence), rosehip was hailed as an alternative to using Retin A creams. It was also claimed that rosehip was rich in tocopherol (vitamin E) until a study carried out by King's College London failed to find any trace of it.
Retin A and vitamin E proved to be red herrings that obscured for a long time what was really going on inside a rosehip seed. It turns out they are high in (fatty) linoleic and linolenic acids as well as vitamin C, all of which are essential for the health of the hair and skin. Flavonoids, a ketonic compound (namely 3-pentenpropyl-kentoe) and trans-rhodanic acids have been detected.
In fact, rosehip seeds are about 77% fatty acids. It is worth reproducing the table that Mike posted, comparing the fatty acid properties of rosehip to argan oil.
Palmitic - 12.0%
Stearic - 6.0%
Oleic - 42.8%
Linoleic - 36.8%
Linolenic - <0.5%
Rosehip seed oil:
Palmitic - 3.17%
Stearic - 0.83%
Oleic - 15.91%
Linoleic - 40.68%
Linolenic - 39.41%
Given that I have had such good results with Kaeline with argan oil (neck and décolleté) that I feel compelled to put rosehip oil through its paces. It can be bought from Skin Actives for $16 for 4 oz.