This is very interesting!
I was doing some research on oleic acid in sebum and found that oleic acid is found in sebum that is lacking in linoleic acid (an EFA - Essential Fatty Acid).
Then I found this at wikipedia.org/wiki/Linoleic_acid:
"Dermatitis is one of the first signs of an Essential Fatty Acid deficiency in both humans and animals. Until 1955, one of the most widely applied treatments for atopic eczema was a high dose of GLA." (Gamma-linolenic acid)
And this at umm.edu/altmed/articles/gamma-linolenic-000305.htm:
"Gamma-linolenic acid (GLA) is an omega-6 fatty acid that is found mostly in plant-based oils. Omega-6 fatty acids are considered essential fatty acids: They are necessary for human health but the body can' t make them -- you have to get them through food."
So, in summary, if we can eliminate oleic acid on the outside of our bodies by not putting it on our skin, but want to keep it from forming in our own sebum, it all goes back to a healthy diet, which will give us the EFA's that we so desperately need to control seb derm, etc.
I actually get a lot of EFA's because I eat flax seeds and take Udo's Oil (and I try to eat well). So I find it interesting that once I stopped introducing oleic acid to my face (i.e. jojoba oil, coconut oil) that my skin had an immediate turn-around (and I do mean immediate - overnight!). Interestingly enough, those good oils that our bodies need so desperately on the inside, are the very culprits when used on the outside. They contain oleic acid, but on the inside of the body they work differently than on the outside.
I'm wondering, however, why the stop of GLA to dermatitis sufferers in 1955? Could it be that since the pharmaceutical companies can't patent a natural product and make money on it, they "convinced" the doctors to steer clear of the natural healers and push the pharmaceuticals? Just a thought.