http://www.krispin.com/lectin.html
There has been some information that lectins may be inactivated by soaking, sprouting, cooking or fermenting. Soaking legumes over night, draining the water, rinsing and draining again does seem to remove or inactivate many of the lectins. Heating seems to remove others in some foods but not all. There is little data to prove that any of these methods remove lectins completely as few foods have been tested and of those that have lectins many seem to remain after processing.
Excerpt from Plant Lectins , Pusztai A, Cambridge University Press 1991 pg.108
Nachbar and Oppenheim (1980) found 30% of fresh and PROCESSED foods contained active lectins. Lectins from green salads, fruits, spices, seeds, dry cereals and nuts (even after roasting) showed activity of potentially toxic lectins. Some of these lectins interact with serum or salivary components and bacteria from the oral cavity (Gibbons & Dankers, 1981).
Another example of the hardiness of lectins is the study by Klurfeld DM and Kritchevsky D Lipids 1987 Sep:22(9):667-8,
Isolation and quantitation of lectins from vegetable oils.
Results-Unrefined soy oils contained 858-2983 mcg/kg. After refining oils contained 24-55 mcg/kg. Both refined and unrefined soy oil contained soy lectins.
From Plant Lectins A Pusztai 1991 Table 6.9 page 179
Common features of toxic (non-nutritive) effects in lectin-gut interactions.
High degree of resistance to gut proteolysis.Binding to brush border cells; damage to microvillus membrane; shedding of cells; reduction in the absorptive capacity of the small intestine.Increased endocytosis; induction of hyperplastic growth of the small intestine; increased turnover of epithelial cells.Interference with the immune system; hypersensitivity reactions. Interference with the microbial ecology of the gut; selective overgrowth.Direct and indirect effects (hormones, etc.) on systemic metabolism.
Especially note #5. The popular Candida Diet is essentially a high protein, low carbohydrate diet which limits starches and sugars and thereby limits lectins. If lectins are a problem for this person (the so-called 'candida' patient) lectin ingestion may be associated with overgrowth of various gut pathogens that may include yeasts and removal of lectins would restore the gut ecology and the gut immune system. If this is true, the diet does not get rid of yeast but relieves the person from symptoms and pathogenic consequences caused by ingestion of lectins to which he or she is intolerant..
Lectins are hardy proteins that do not break down easily. They are resistant to stomach acid and digestive enzymes.