I've been taking milk thistle from Holland and Barrett for some time. I don't believe it clears P (certainly not in my case) but it helps restore liver function ... like every else anyone who claims to CURE P is economical with the truth - take it with a grain of salt, because those of us who have lived with P for longer than we care to remember, realise there is NO cure; there are, however, several management programmes and it's trial and error to find which one works best for you.
Currently I'm on the fresh veggie juices and fruit smoothies twice daily together with supplements to include milk thistle, folic acid, selenium combined with zinc, calcium and vitamin D3 (for bones); glucosamine (for bones), peppermint to aid digestive system, probiot supplements (for a month); and have just had a course of uvb which has sent P into remission. Moisturising regularly (twice daily) is also strongly recommended.
Wishing you the best of luck finding out what works for you, try to ease off dairy products - perhaps thereafter, wheat products and see if those make a difference too - I've gone off those and alcohol as well. It's not soo difficult once you begin .. 21 days in and euphoria takes over (!); they say the first 21 days of any lifestyle change are the toughest - thereafter you can achieve anything. Keep a diary too and revert back to it if you have a flare to see what the possible causes might be.
But milk thistle alone will not CURE P - it may, when combined with additional helpful practices, relaxation therapies together with diet/lifestyle change, aid your immune and digestive systems ... let us know how you get on.
Meantime
hugs
BB