[Diet, nutrition and rheumatoid arthritis]

Rheumatoid Arthritis (RA) is a chronic inflammatory disease resulting in diarthrodial joints inflammation (particularly joints of hands, wrists, feet, knees, cubitus, ankles, shoulder, etc.) that is manifested by swelling and functional impairment. The associated complications, osteoporosis and cardiovascular disease, make RA important in public health terms. During the active phase of disease, elevated plasma concentrations of inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and acute-phase proteins, lead to reduction of fat free body mass (FFM) with a loss mean of 15% of cell body mass (CM) and consequent reduction of muscle strength. The pharmacological therapy (non steroidal anti inflammatory drugs (NSAIDs), slow acting antirheumatic drugs and corticosteroids), have the potential to cause side-effects, such as gastrointestinal bleeding, bone loss beyond to increase the requirement of some nutrients and reduce their absorption. The diet may play role in the management of RA, particularly in alleviating the symptoms of the disease, combating the side-effects of therapy and reducing the risk of complications. The increase of the caloric and proteic intake is not sufficient to offset a increased metabolic rhythm and important proteic catabolism but a diet balanced may warrant an adequate intake of nutrients. The carbohydrates of the diet provide 55-60% of the caloric intake, the diet is normo-proteinic or hyper-proteinic in the active phase of disease, and lipids represent 25-30% of the caloric intake (saturated, monounsaturated, polyunsaturated fatty acids in the ratio 1:1:1). omega-3 fatty acids supplementation, in combination with reduction of fatty acids omega-6 and adequate intake of monounsaturated fatty acids induce improvement in symptoms and sometimes a reduction in NSAIDs usage. Proper antioxidant nutrients (Vitamin A, Vitamin C, selenium) may provide an important defence against the increased oxidant stress and a supplementation of folate and vitamin B12, in patients treated with methotrexate (MTX), reduce the incidence of side effects and offset the elevation in plasma homocysteine frequent in these patients. Calcium and vitamin D, in patients treated with corticosteroids, reduce the bone loss, while a supplementation with iron may prevent anaemia. Finally, elimination diets may be feasible therapy only in patients with positive skin prick test.