There are number of supplements that have been proven to be helpful for RA.  Vitamin D, cod liver oil and oddly enough, tart cherry juice. Diet can also have an effect - for instance, the Mediterranean diet has been proven to have anti-inflammatory properties in a whole-grain diet can be helpful, as well.

When you have a chronic disease like RA, you will meet people who swear to you that that product X. or supplement Y has cured their aunt's cousin's arthritis.  Take everything with a large grain of salt, do plenty of research to check out the claims and keep in mind two things: at present there is no cure for RA and if it sounds too good to be true, it probably is.  That said, there are a number of alternative treatments that can be helpful in managing your symptoms and I generally recommend that people supplement the regular "Western medicine" treatment of the disease with a variety of supplements and treatments like e.g. vitamin D, cod liver oil, acupuncture, etc.