More On Grain Lectins & Gluten
What Are Lectins?
Grains and other plants, including soy and those in the nightshade family (tomatoes, potatoes, legumes) contain a high level of a carbohydrate binding protein (glycoprotein) called lectin. Lectins are found in all foods, certain foods more than others, and the same food may contain varying amounts of lectins depending on processing, when and where the plant was grown, and species. They are in various plant families and eaten in large amounts by humans and animals on a regular basis 1. Lectin is a powerful natural insecticide in seeds of the grass family, e.g. rice, wheat, spelt, rye, which have high levels of these defensive glycoproteins. Some forms of lectin have shown toxic effects in humans and may be linked to a number of intestinal, autoimmune, and digestive diseases. There are many forms of lectins and not all of them are necessarily harmful or toxic to mammals 1.
In plants, lectin has many functions. It has been shown to help protect the plant seed, store nitrogen, and help bind the appropriate soil bacteria for symbiotic survival. In addition, it has protective qualities that help defend the plant from predators that may eat them 2. This is great for the plant, but what about for ‘predators,’ like us, who eat them?
How are some lectins harmful?
Plant lectins, like the glaidin component of gluten, are able to bind the glycoconjgates of other organisms, including mammals, which are present along the inner mucosal lining of the intestines. Some lectins bind exclusively to animal glycoproteins not found in plants at all. This suggests that lectins serve as a protective element against insects and other animals by targeting proteins that are present in predators. A special feature of wheat lectins is their ability to survive digestion by the gastrointestinal tract. This is their purpose in nature, to protect the plant and indicate to predators that this is not a good food source. Instead of being broken down, they bind to the cells lining the digestive tract which can cause local and systemic reactions considered to be anti-nutritive and toxic 1. Since lectins can bind to the glycosyl groups of cell lining in the intestinal wall, and are resistant to gastric and intestinal digestion, they can cause lesions and interfere with nutrients absorption9. The reaction between the cell membrane and lectin is believed to result in an alteration of the cell function. When WGA binds the cell walls, it can be engulfed and transported into the blood stream, where it can travel to other organs. It causes irritation by creating more entry space for antigens and other particles to enter the blood stream. This results in what is called leaky gut syndrom, and inflammation. WGA, wheat germ agglutinin which is a type of wheat lectin, causes change in cell function which can include aggregation, deformability of erythrocytes, permeability, and binding properties of mitogens 9. Grains have been implicated in a number of diseases including Celiac disease, autoimmune diseases, diabetes, obesity, IBS, rhumetoid arthritis, IgA nephropathy, autism, and many more.
Overconsumption
First, let us say that lectin is a broad category of proteins found in plants and animals. Not all of them are bad, and there are various ways to detoxify or inactivate the harmful effects through processing and preparation. In fact, some of them may be good, helping defend against cancer, bacteria or fungi. Like most things, too much of anything can be harmful. In this case, the increasing amount of refined wheat and grains the average person consumes on daily basis is rather high and growing globally. The average per capita grain consumption was 45% higher in 2000 (14 years ago) than it was in the 1970s 2. This increased, unbalanced consumption of grains may have negative long term consequences on health.
There are many forms of lectin, the most recognized as harmful being WGA, wheat germ agglutinins, which are proteins that protect wheat from pests. This is great for plants, but no so great for humans. Numerous studies have shown the damaging effects of WGA on intestinal cell walls and the cell walls of blood and lymphatic vessels, as it is transported across the gut wall into the systemic circulation3. This is thought to be behind many diseases such as leaky gut syndrome, inflammation, irritable bowel syndrome, as well as rheumatoid arthritis and neuropsychiatric disorders 1,3–8.