Lectins are a large class of sugar-binding proteins that can be found in all forms of life. In plants, lectins are part of the natural defense against microorganisms, pests, and insects. Although lectin has been considered a low-level toxin, many members of the lectin protein family can agglutinate (clump together) and become problematic for human health.
The most common potentially toxic lectin containing food groups are:
Grains (especially wheat but also rice, oats, rye, barley, and corn)
Legumes (all dried beans, including soy and peanuts)
Nightshades (includes potato, tomato, eggplant, and pepper)
Major harmful effects of dietary lectins are:
Resistant to digestion – overfeed certain species of gut bacteria that feed on lectins which may lead to gut dysbiosis
Damage of gut epithelial lining – lectins may damage intestinal barrier cells or open up the tight junctions between the cells, increasing the development of intestinal permeability, which may increase the risk for autoimmunity.
Stimulation of the immune system – lectins can provoke antibodies causing immune responses.
Human immune systems can react to food lectins and produce IgG and IgA antibodies. Detection of these antibodies can help manage eating habits (in consultation with a dietitian) and reduce the risk of development of more serious conditions.
How Do Aquaporins differ From Lectins
Aquaporins, also known as “water channels”, are an integral membrane that forms pores in the membrane of biological cells to facilitate water transport between cells.
Aquaporins are found in all cells and help move water through the cells in an organized manner. Aquaporin 4 (AQR-4) is the most prevalent aquaporin channel in the central nervous system.
Aquaporins from food sources (e.g., spinach, soy, corn, tomato, etc.) show similarity to the brain AQR-4. Since aquaporins from food are highly stable during food preparation and may enter human body as intact proteins, they become antigenic and trigger the production of antibodies. The antibodies against food aquaporins can be cross-reactive to human AQR-4 and induce severe neuroautoimmune disorders such as multiple sclerosis.
Measuring antibodies to food aquaporins is suggestive of adjusting the diet in patients who have neurological autoimmunity and/or those with a family history of such disorders.