The role of diet and nutrition in both OA and RA has been studied since the 1930s, but there is little agreement as of 2007 regarding the details of dietary therapy for these disorders. One clear finding that has emerged from seven decades of research is the importance of weight reduction or maintenance in the treatment of patients with OA, and the need for nutritional balance and healthy eating patterns in the treatment of either form of arthritis. Findings regarding the use of dietary supplements or CAM therapies will be discussed in more detail below.
Various elimination diets (diets that exclude specific foods from the diet) have been proposed since the 1960s as treatments for OA. The best-known of these is the Dong diet, introduced by Dr. Collin Dong in a book published in 1975. This diet is based on traditional Chinese beliefs about the effects of certain foods inincreasing the pain of arthritis. The Dong diet requires the patient to cut out all fruits, red meat, alcohol, dairy products, herbs, and all foods containing additives or preservatives. There is, however, no clinical evidence as of 2007 that this diet is effective.
Another type of elimination diet, still recommended by naturopaths and some vegetarians in the early 2000s, is the so-called nightshade elimination diet, which takes its name from a group of plants belonging to the family Solanaceae. There are over 1700 plants in this category, including various herbs, potatoes, tomatoes, bell peppers, and eggplant as well as nightshade itself, a poisonous plant also known as belladonna. The nightshade elimination diet began in the 1960s when a researcher in horticulture at Rutgers University noticed that his joint pains increased after eating vegetables belonging to the nightshade family. He eventually published a book recommending the elimination of vegetables and herbs in the nightshade family from the diet. There is again, however, no clinical evidence that people with OA will benefit from avoiding these foods.

