Lectin is a plant compound found in almost all foods. In high amounts, it can be poisonous.
The foods that have the highest proportion of people allergic to them also contain the highest amounts of lectin.
This foods highest in lectin include peanuts, soy, dairy, eggs, wheat and shellfish.
(Other allergies/reactions come from processed foods - grains, sugars, preservatives - which are not necessarily high in lectin.)
Lectin binds to the intestinal walls, and blocks nutrients from being absorbed and creates gaps in the intestines where undigested food can leak into the bloodstream. This creates what we call an allergic reaction, ranging from a stuffy nose to full-blown hives. These food sensitivities triggered by lectin can be removed and return many individuals to cheery, vibrant health.
The best bet to determine your food sensitivities is to do Elimination Therapy, where you remove and reintroduce foods to your body one at a time. Search “Elimination Diet” online for a complete description.