Lectins have been implicated in almost every disease condition in some way or another. Research into these proteins has revealed they play a role in autoimmune conditions such as Hashimoto's Thyroiditis, Type 1 Diabetes Mellitus, Coeliac Disease, Chron's Disease and Rheumatoid Arthritis. They appeare to also contribute to skin conditions like eczema and psoriasis as well as common digestive complaints including bloating, diarrohea and constipation.
Lectins are complex proteins found in all foods, mostly in plants. In plants they guard against moulds and parasites, protecting the plant from disease. The lectin does this by attaching to sugars within the invader and blocking their use of this sugar, which ends up killing whatever is attacking the plant. Lectins are very tough little molecules and won't easily break down through cooking processes, let alone through human digestion. Some lectins are well tolerated by humans and don't cause any problems and others are not tolerated and can even be deadly. Ricin, a lectin found in the castor bean is highly toxic and was used by the KGB in an assassin attack!
Lectins bind to certain sugars within cells, in the same way they bind to sugars in plant enemies. There are eight essential sugars that have been identified that have specific important biological functions throughout the human body. Each lectin has an affinity for a particular sugar, and wherever it finds it in the body, it binds tight and interferes with the sugar's normal function. For example, the lectins in wheat bind to a sugar called n-acetyl glucosamine (NAG). And NAG is found in the mouth, intestines, pancreas, thyroid, kidney, in our muscles and in the myelin sheath that insulates the nerves.
The most common foods that contain lectins not well tolerated by humans include:
The simple fact is that our ancestors did not eat these foods and our immune systems have not evolved to cope with the massive amounts we consume in our modern day lives.
Lectins are also found in animals that eat or are fed grains. This is why milk from grass fed cows is sometimes more tolerable than from those fed grains. Lectins are also found in viruses and bacteria, where they are referred to by their alternate name - Haemagglutinin. The "swine flu" is called H1Nl and the bird flu, H5Nl. The H in these viruses refers to haemagglutinin. It is probably lectins that make you ache when you have flu.
Lectins can be very damaging to our digestive system, hich underpins our overall health. Lectins can attach to the walls of our digstive tract and damage the lining, leading to increased gut permeability causing "leaky gut". As the gut lining is now compromised, lectins can gain entry into the bloodstream where they travel to other organs, binding to receptors in the kidneys, thyroid, pancreas, brain, blood vessel walls and the adrenal glands. Other substances can also make it through this damaged gut wall, including large molecules of food, which can trigger allergies and anaphylactic reactions.
Lectins are the basis for the blood type diet as thwy have a special affinity for the receptors on our red blood cells. Remember that every cell in the human body has receptors on its surface for hormones to bind to, and these receptors contain sugar molecules (they are made from glycoproteins, where the glyco part stands for sugar). These receptors have different shapes depending on the hormones they are designed to bind with. Depending on our blood type, our red blood cells have different receptors with an affinity to certain lectins. The word lectin comes from the Latin, "I choose", which is quite appropriate as lectins are very specific as to which receptors they bind to.
The basis of the blood type diet is to avoid the foods containing the lectins with an affiliation to your red blood cells. It is debatable as to whether things are as straighforward as this when it comes to lectins. Still, any diet that limits your exposure to lectins may be a step in the right direction if you seem to react to them.
One thing we know to happen is that when lectins bind to our red blood cells they cause the cells to "agglutinate", which means they clump together. As you can imagine, this is not a good thing. It makes it more difficult for our blood to perform the task of delivering nutrients and removing wastes. Agglutinated red blood cells, in the worst sense, are more prone to clot and thereforw increase the risks associated with clots - stroke, heart attack and aneurism. Ricin, the lectin I mentioned was used by the KGB, is so lethal because it causes all red blood cells to agglutinate within minutes, causing massive clotting and death.
Research has shown that there may be a real potential for lectins to have a negative influence on those with a genetic predisposition to autoimmune conditions. Lectins can trigger our immune system to respond and destroy the foreign lectin and the cell it is attached to. This ability to illicit an immune response is why lectins are termed "antigenic" and is why they have been implicated in auto-immune conditions. As with our red blood cells, lectins can cause the cells of the organ to clump together and immune system is sent in to attack the lectin (and ends up attacking its own cells too). Lectins may also strip away certain essential sugars from cell surfaces, making them appear foreign to the body's immune system. They may also evoke the immune system by binding irreversibly to particular cells or proteins, forcing white blood cells to remove the affected cells.
As I mentioned earlier, viruses and bacteria also contain lectins and this may be why autoimmune conditions like Guillan-Barre Syndrome, Multiple Sclerosis, Type 1 Diabetes and some types of arthritis tend to appear after an infection or illness.
Some lectins are able to mimic hormones, which can lead to a whole host of diseases. Research has shown that lectins found in potatoes, lentils and wheat have an affinity for the insulin receptors on our fat cells. Insulin binds to our fat cells when it needs to store away excess glucose for later use (that is, when we've eaten too much). The lectins can bind to these same receptors and mimic insulin, telling the fat cells to take in more glucose and grow. The more of these lectins in the diet, the more fat cells grow.
During all of my research in lectins, this question has been at the back of my mind. Mostly because I know how much I like to eat bread, at least every now and then! Fortunately, lectins are completely absent from grains during the sprouting process. And there are some great breads available made from sprouted grains. In fact, sprouted grains contain a lot more nutrition as the little sprout needs all the help it can get to grow into a plant.
The traditional ways of cooking some legumes and grains can also reduce the amount of lectins in the food. This may help you to tolerate the food more, if you seem to have troubles with it. In Indian cooking, lentils take days to prepare as they are soaked overnight, rinsed, soaked again, rinsed again and then cooked for a long time. You may find that eating lentils cooked in this traditional way makes them easier to digest (and you don't get "windy") and this is because many of thew lectins have been destroyed.
One of my medical colleagues is very much into avoiding lectins, and he was telling me of a new type of "gluten-free" wheat that is being developed. I havewn't looked into it yet, but I assume that the wheat plant is somehow genetically modified and this makes me worried. I think we've tampered enough with wheat and perhaps it is easier to just avoid eating it and look for other alternatives.
The herb Bladderwrack can remove lectiins!
Lectinology (the study of Lectins, yes - it is a real word) is in it's infancy, but I am sure you agree that it is a fascinating area of research with wide reaching implications for our health as a species. We don't want lextins to be for us like a meteor was for the dinosaurs. Or did they start eating foods they weren't designed to eat too? And while we are in a lighthearted mood at the end of this article, I'd like to share some good news about lectins. While they may be found in grain-based alcohol like beer, thwey are certainly NOT found in wine or in distilled spirits like vodka. I'll toast to that!
Date posted: 2013-10-09 | posted by: debras