Anecdotally (fwiw), in my household my daughter had been struggling with severe rashes that appeared to be triggered by food. An elimination diet caused us to conclude that she is highly reactive to vegetable oils (canola (rapeseed) oil, sunflower seed oil and soybean oil have all been introduced as food challenges and all produce a reaction within 3-6 hours)
We currently cook only with tallow and her symptoms have improved considerably (we tried olive oil and avocado oil for awhile but it was unclear on her)
As a challenge to anyone objecting to this comment, I ask you to look up the history of canola oil and say whether such a substance would be accepted into the food supply today.
And my question to everyone is, what is the mechanism by which seed/vegetable oils could lead to rashes? The only theory I've heard has been around omega-3/6 balance, but I am looking for alternative theories. I conjecture it has something to do with heating, as she isn't affected by ice cream containing these oils.