Personal experience. First not all people are sensitive to all the same things: Biochemical individuality.
- I was in near fatal auto accident 1972 lingering painful leg issues
- Past athlete in HS so wanted to get back into shape after years of recovery - ran 5 mi for year - pure painful torcher
- Switched to walking - continued pain in joints especially bad accident legs
- Heard of no nightshade diet read about animal studies in early 2010's
- Partner and I did suggested three weeks no nightshade diet - amazing how many foods are riddled with potatoes, tomatoes, hot peppers, regular peppers, egg plant, paprika and we didn't smoke tobacco.
- Results amazing it was worth it to us to adapt to no nightshade diet
- Creative recipes: pumpkin puree for tomato sauce, ginger and horse radish for peppers, etc.
Three no nightshade tales (many more I can tell):
- My optometrist and friend had very bad arthritis so I told her my story. Being an MD she wondered about the science but went off the nightshade anyway with great results (you have to check labels its in lots of things - potatoes in bread!?!?) She went to an optometrist continued Ed. event. Lunch was served, with speaker, she paid little attention to what she ate. It was riddled with all kinds of nightshade. Next day she awoke with great joint and arthritis pain. For her no nightshade diet is her choice. To this day still on it!
- Years after I had gone faithfully off the nightshades, my sister served a meal full of nightshade. I threw up my hands and ate with abandon, what the heck. Same thing, the next day I ached in places I hadn't for years.
- Since I used to do bodywork, I saw clients who spoke about their love of tomatoes and potatoes etc., while telling about their joint aches. One client who was terminal wanted to have freedom from pain. He told of loving spaghetti and that he had stopped smoking. I explained to him what had helped me and that it was my own experience not part of the bodywork. He went off the foods, came back two weeks later and said, "I have not felt this good for over seven years." Some time went by and I got a message from his sister with whom he lived in his last days, "He died but thank you very much for making my brother's latter days so much more comfortable."
I respect both regular MD's and a variety of holistic doctors. But a couple quotes in my early studies stuck with me: Biochemical individuality and you may have an imbalance of nutrients, vitamins and minerals but you will never be deficient in aspirin.

Three weeks without the nightshade family and if you don't feel any change and still have arthritic symptoms keep eating the nightshade. If you do have pain relief go on the no nightshade diet for three months. Then choose the way you want to feel. Personally I am so glad for the huge amount of relief I have been able to count on for many years without being dependent on medication.
@farmersmith