LECTINS IN THE DIET
Lectins are apparently most widely distributed in plants, where they were found in almost 1000 plants of some 3000 examined in recent years. They are particularly abundant in legumes and they account for between 1.5 and 3 percent of the total protein content of soy and jack beans. The second most common source of lectins are seafood.
Nachbar and Oppenheim also noted high levels of lectin activity in dry roasted peanuts, Corn Flakes, Rice Krispies, and Kellogg's Special K. The banana agglutinin was actually enhanced by heating, and was inhibitable by n-acetyl glucosamine (NAG) and N-acetylgalactosamine (blood group A antigen) glycoproteins.
Phytohemagglutinins from kidney beans can resist mild cooking and retain lectin activity even at 90 degrees C for 3 hours. Pre-soaking the beans however resulted in complete loss of lectin activity. Several investigators noted year-to-year and batch-to-batch variations in the lectin content of foods, so the occasional lectin is likely to occur even with foods normally considered safe.
Nachbar tested 88 common food items and reported erythrocyte agglutination activity in 38. Many foods showed agglutinating activity so substantial that the extracts could be diluted several fold. Crude extracts of various foods tomato, lettuce, cucumber, wheat bran and whole wheat, sesame and sunflower seeds, vanilla yogurt, coconut, banana and baby food banana, carrot, onion, apple, alfalfa and soya protein have also been found to bind, and in some instances precipitate the components of human saliva, including cellular debris and bacteria.
This may have some significance in the development of caries. Interestingly, avocado lectin inhibited the sucrose dependent adherence of S. mutans to plaque pellicle. Approximately 1 to 5% of the ingested dietary lectins are absorbed into the blood stream. Here they can clump and bind to red and black blood cells, destroying them. It has been proposed that much of the low grade anemias seen In the third world may be resulting from destruction of red blood cells by lectin rich grain and bean diets.
RESISTANCE TO DIGESTION
Although many lectins are destroyed by normal cooking (which is why grains and beans are edible), many are not. Relative resistance to lectins was part of the classic description of wheat germ agglutinin (WGA) made by Joseph Charles Aub in 1963. WGA as Freed points out is in fact one of the more heat sensitive lectins, being destroyed after 15 minutes at 75 degrees C, whereas other wheat lectins in gluten and gliandin resist autoclaving at 110 degrees C for 30 minutes. Gibbons and Dankers noted that in over 100 food plants found to contain active lectins, seven were autoclave resistant (apple, carrot, wheat bran, canned corn, pumpkin seeds, banana and wheat flour).
Lectins which are especially rich in di-sulphide bonds such as WGA are very resistant to proteolytic enzymes, detergents, urea, alkalis and acids. Foodstuffs are naturally rich in fiber and are an important cause of allergies. Dietary lectins also stimulate mast cells which can degranulate and release stored histamine, leading several researchers to ascribe a role for dietary lectins in the genesis of food allergy.
However it is not generally known why some individuals become sensitized to food in their diets. In an attempt to clarify this, celiac disease has been extensively studied, since patients with this disease usually normalize when placed on a gluten free diet. Researchers reported that the mucous membranes of celiac patients showed sugar residues which were capable of binding to the lectins in wheat germ, which resulted In a cytotoxic reaction. Rats treated with Concavallin-A or wheat germ lectin developed a gut membrane that was paradoxically impermeable to small molecules, but very permeable to large, highly allergenic molecules, a situation which is mimicked in food allergies and celiac disease.
Lectins are found in many foods, not just grains, and consumed in smaller amounts, your body will do just fine with them. But foods that have large amounts of lectins are more problematic. Some of the lectins and foods that cause leaky gut include wheat, rice, spelt and soy.
Lectins can be deactivated by soaking, sprouting, fermenting or cooking. Only the lectins found in legumes seem capable of surviving all of these deactivation methods.
Not everyone appears to be negatively affected by lectins. Many people may be having problems but they just don’t realize it until they remove lectins from their diet (normally wheat and dairy) and experienced much improved energy and weight control. And many people are able to tolerate lectins mainly due to the balance of gut flora (adequate beneficial flora serves as a protective barrier against substances that travel through the intestines, including lectins).
If you have any lectin-related health issues like arthritis, allergies or autoimmune disease, it might be very helpful to reduce your intake of lectins, especially from wheat. It’s also very important to balance immunity by working on stress management and gut health.
IFM (functional medicine) approach to fixing the gut:
- Remove stressors: get rid of things that negatively affect the environment of the GI tract including allergic foods, parasites and potential problematic bacteria or yeast.
- This might involve using an allergy “elimination diet” to find out what foods are causing GI symptoms or it may involve taking medications or herbs to eradicate a particular bug
- Replace digestive secretions: add back things like digestive enzymes, hydrochloric acid, and bile acids that are required for proper digestion and that may be compromised by diet, medications, diseases, aging, or other factors.
- Help beneficial bacteria flourish by ingesting probiotic foods or supplements that contain the “good” GI bacteria such as bifidobacteria and lactobacillus species, and by consuming the high soluble fiber foods that good bugs like to eat, called prebiotics.
- Probiotics are beneficial microorganisms found in the gut that are also called “friendly bacteria.” Use of antibiotics kills both good and bad bacteria. Probiotics in the form of supplements or food are often needed to help reestablish a balanced gut flora. Fermented foods, such as yogurt, miso, and tempeh are food sources of probiotics.
- Prebiotics are food ingredients that selectively stimulate the growth of beneficial microorganisms already in the colon. In other words, prebiotics feed probiotics. Prebiotics are available in many foods that contain a fiber called inulin, including artichokes, garlic, leeks, onion, chicory, tofu, and other soy products. Grains such as barley, flax, oats, and wheat are also good sources of prebiotics. Another good prebiotic source is a supplement called “fructo-oligosaccharide” or FOS.
- Help the lining of the GI tract repair itself by supplying key nutrients that can often be in short supply in a compromised gut, such as zinc, antioxidants (e.g. vitamins A, C, and E), fish oil, and the amino acid glutamine.
- It is important to pay attention to lifestyle choices. Sleep, exercise, and stress can all affect the GI tract. Balancing those activities is important to an optimal digestive tract.