Lectins are carbohydrate-binding proteins present throughout nature that act as agglutinins. Approximately 30% of our food contains lectins, some of which may be resistant enough to digestion to enter the circulation. Because of their binding properties, lectins can cause nutrient deficiencies, disrupt digestion, and cause severe intestinal damage when consumed in excess by an individual with dysfunctional enzymes. These effects are followed by disruption of intestinal barrier integrity, which is the gateway to various autoimmunities. Shared amino acid motifs between dietary lectins, exogenous peptides, and various body tissues may lead to cross-reactivity, resulting in the production of antibodies against lectin and bacterial antigens, followed by autoimmunity. The detection of immunoglobulin G (IgG) or immunoglobulin A (IgA) antibodies against specific lectins may serve as a guide for the elimination of these lectins from the diet. It is proposed that this process can reduce the peripheral antigenic stimulus and, thereby, result in a diminution of disease symptoms in some-but not all-patients with autoimmune disorders.