Rheumatoid arthritis is the second most common form of arthritis that affects more than half a million adults in the UK. Medications can be used to relieve symptoms and/or help slow the progression of the disease, but some medicines have side effects and thus patients frequently turn to complimentary therapies including dietary modification. Studies of the effects of diet and nutrient supplementation on rheumatoid arthritis are hampered by study design issues (e.g. differences in the wide spectrum of clinical phenotypes among study participants). Despite this, there is good evidence to suggest that fish oil supplements may be helpful in relieving some symptoms, such as decreased morning stiffness, in those with long-standing rheumatoid arthritis. Evidence relating to specialised diets, plant seed oils, antioxidants, minerals and trace elements, folate and other B-vitamins, vitamin D and antioxidants are also considered in this paper. This paper provides a general overview of the scientific evidence of the role of specialised diets and nutrients in the treatment of rheumatoid arthritis.