I have heard good results of the mineral selenium.  details of food containing this mineral are readily available on the web but I understand that soil levels in the UK are extremely low anywhere but Norfolk.  I and my mother (91) have taken selenium as it is known to be an excellent antioxidant for several years and neither of us shows any sign of arthritis.  The Office of Dietary Supplements (NIH) states that "surveys indicate that individuals with rheumatoid arthritis, reduced selenium levels in their blood [50-51]. In addition, some individuals with arthritis have a low selenium intake [52].
The body's immune system naturally makes free radicals that can help destroy invading organisms and damaged tissue, but that can also harm healthy tissue [53]. Selenium, as an antioxidant, may help to relieve symptoms of arthritis by controlling levels of free radicals [54]."  hope this helps.

hazel glendinning