Common dietary staples, such as wheat, rice, beans and peas, may exacerbate the symptoms of rheumatoid arthritis in susceptible individuals. This is the conclusion of a review article by Dr Loren Cordain and colleagues (Colorado State University, Fort Collins, Colorado).
Writing in the British Journal of Nutrition (2000;83:207), the authors explain that rheumatoid arthritis is an autoimmune disease which, like most autoimmune diseases, is thought to develop via the interaction of an environmental factor (or factors) with a specific hereditary component. The mechanism by which this occurs is not clearly defined, but the process of "molecular mimicry" in which a specific foreign antigen interacts with an individual's own antigens may be involved, they say.
The authors propose that substances known as lectins, present in some foods, can influence gastrointestinal structure and function by interacting with enterocytes and lymphocytes to facilitate the transport of antigens (derived from both the diet and the gastrointestinal tract) to the peripheral tissues. If the foreign antigens are similar in structure to the individual's own antigens, their presence in the tissues may cause persistent peripheral antigenic stimulation. This may ultimately result in the development and exacerbation of rheumatoid arthritis in susceptible individuals, they say. Lectins are glycoproteins which are found in a range of foods, including peanuts, wheat, soya beans, barley, lentils, rice, mung beans, kidney beans, broad beans, peas and potatoes. Elimination of dietary lectins may reduce peripheral antigenic stimulation and result in a reduction in disease symptoms in certain patients with rheumatoid arthritis, the authors conclude. They indicate that the above mechanism could also apply to other auto-immune diseases.