When I started testing my diet and its effects on my psoriasis, the foods that had the strongest effects were the ones that showed up first. In restrospect, it is clear that most of the bad ones are things that are bad for healthy living, no-matter what your ailment might be. In general, if you eat healthy then your body is better able to look after itself without any help from the medical profession.
Right at the top of my list is fried food. At that time I used to eat a fair amount of fried food, in the form mostly of French fries, fried fish and stir fries. I saw in my diet diary that my reaction to some of these items was very rapid. Within 3-4 hours the itch and redness would start.
I cut fried food totally out of my diet while I continued to test for other foods. After my skin had cleared and remained clear for many months, I gradually reintroduced some of these things in moderation but generally with changes in how they were cooked.
Whenever possible I replaced fried meats and fishes with grilled or baked. French fries were replaced by oven-baked chips. Stir fries and risottos still need some frying but I changed to cooking over medium heat instead of high and cooking with extra virgin olive oil in place of sunflower oil.
I found over the years that it was when travelling that it was most difficult to stick with a diet free of fried food, so it was during and soon after trips that my skin would sometimes deteriorate. When away from home it is all too easy to go into the nearest fast food joint to grab a quick meal. A burger and chips was the normal fare. Since then most of the fast food chains have buckled under the pressure to offer healthy options, so salads, healthy sides and grilled chicken burgers are now on most menus and give the opportunity to eat quite healthy meals if you take care.
Now my skin is about 99% clear, with just a few small spots on my back and elbows. Last week we had a treat of take-aways from KFC. They had no grilled chicken ready, with a wait for 10-15 minutes for grilled instead of the standard fried options. We ended up with original fried chicken boxes. This is how it is with fast foods, we go into the shop expecting to come out a few minutes later with our order. The 10-15 minute wait is not in the spirit of fast food, so we took the fast alternative. Within about 4 hours I could already feel the itch from it. Next time I will wait the few minutes, in the interests of better health.