Hypothyroidism, often subclinical is common in RA and can make RA symptoms worse. On this forum there has been a lot of discussion on diets and their role in decreasing RA symptoms. Less often however discussion on why and how they effect the dysfunctional situation. When it comes to supporting normal thyroid function with diet, there is in fact many things you need to be aware of and can in fact do. Here is a link that in my view has a lot of useful information.