Immune Reactivity to Raw and Processed Foods and Their Possible Contributions to Autoimmunity

It is now known that diet or food is one of the environmental factors that can induce or contribute to autoimmunity. In a healthy person with a normal functioning immune system, food substances encounter no resistance and are allowed passage through the immune barriers without triggering immune reactivity. However, clinicians are becoming increasingly aware that modern food-processing methods can increase or decrease the immune reactivity of foods, including allergic reactions. Immune reactions to undigested food antigens could result in the production of IgE antibodies, which are involved in immediate immune reactivity, and in IgG and IgA antibodies, which are involved in delayed immune reactivity. Currently, measurements of these antibodies are generally only performed against antigens derived from raw foods. However, testing for food reactivity based only on raw food consumption is inaccurate because people eat both raw and cooked foods. Even home-cooked foods undergo different kinds of preparation or processing. Food processing can change the structure of raw food materials into secondary, tertiary, and quaternary structures that can have different reactive properties. This can affect the body's normal oral tolerance of food, causing the immune system to mistakenly identify food as a harmful foreign substance and react to it immunologically, leading to food immune reactivity. This abnormal reaction to food molecules can lead to the production of antibodies against not just target food antigens but also the body's own tissues, which can have significant implications in autoimmunity induction due to cross-reactivity and the other mechanisms discussed here. We hope that this present review will stimulate further research on the role of modified food antigens in the induction of autoimmunity based on some or all of the key points discussed in this review.