Food Lectins in Health and Disease: An Introduction

Food Lectins in Health and Disease: An Introduction

In recent years there appears to be a growing epidemic of people suffering from chronic digestive and autoimmune diseases. Food intolerances or sensitivities may be the cause of the problem. Most people, including doctors, have no idea how foods they eat can contribute to their chronic illness, fatigue and digestive symptoms.

However, there is much evidence in the medical literature and lay experience about how food causes and/or contributes to the current epidemic of chronic and autoimmune diseases. There are several diets that are used by many people with varying degrees of success to improve their health, despite a general lack of scientific evidence supporting their effectiveness. One of the clues to the cause and relief of foodborne illness may lie in proteins known as lectins, which are found in all foods.

Animal and plant food sources both contain complex proteins known as lectins. These proteins typically have the ability to bind to sugars or carbohydrates on the surface of human cells. Some of these proteins can cause human red blood cells to clump together, a process called agglutination. The process of agglutination occurs when someone receives the wrong blood type during a blood transfusion. In fact, the clumping of red blood cells specific to each person or group of people is the basis for blood group testing. There is some data that blood types can influence how people respond to certain foods, although blood type-specific diets appear to be disproved. The attachment or binding of certain dietary lectins can trigger a variety of cell-specific effects. These reactions can mimic hormones or cause changes in cells. This is called molecular mimicry.

Most plants contain lectins, some of which are toxic, inflammatory, or both. Many of these plant and dairy lectins are resistant to cooking and digestive enzymes. Grain lectins, for example, are fairly resistant to human digestion but are well suited to ruminants such as cattle with multi-chambered stomachs. Therefore, lectins are present in our food and are often resistant to our digestion, and some have been scientifically proven to have significant GI toxicity in humans. Others have been shown to be beneficial and perhaps even cancer protective. Either way, plant and animal proteins are foreign proteins and are treated positively or negatively by digestion and our immune system.

The human digestive system was created to process a variety of plant and animal proteins through the process of digestion and excretion. Some plant and animal proteins or lectins are highly toxic to humans and cannot be eaten without being fatal, as is the case in castor beans and some mushrooms. Other foods require preparation before they can be safely eaten. Preparations may include peeling, prolonged soaking, and cooking like kidney beans. Other foods may be poorly tolerated due to a genetic predisposition or an underlying pre-existing food allergy or intolerance. Others are tolerated to some degree or quantity, but not in large quantities or frequently. People who are intolerant to the milk sugar lactose due to an inherited or acquired deficiency of the lactase enzyme can tolerate small amounts, but may experience severe gas, bloating, abdominal pain, and cramps with explosive diarrhea when a large amount of foods containing lactose are consumed. Foods may become intolerable for some people after their immune system changes or the intestines are injured for another cause.

Of the food lectins, cereals/cereal lectins; milk lectins; and legume lectins (particularly peanut lectin and soybean lectin) are the most common, associated with reports of exacerbation of inflammatory and digestive diseases in the body and improvement of these diseases and/or symptoms when avoided. Recent research by Loren Cordain, PhD., has shown that these lectins can effectively serve as a “Trojan horse,” allowing intact or nearly intact foreign proteins to penetrate our natural gut defenses and get behind the lines to cause damage well beyond the gut, often into the joints, brain, and skin of affected individuals. Once the gut is damaged and the immune system is breached, the result is what some call “leaky gut.” In addition, many people who develop “leaky gut” not only experience intestinal symptoms such as bloating, bloating, diarrhea, and abdominal pain, but also other symptoms outside the gut, or extraintestinal symptoms. Commonly affected areas include the brain or peripheral nerves, skin, joints and various body glands. Continued exposure of the intestine to these toxic food lectins results in a sustained stimulation of the body's defense mechanisms in a dysfunctional manner, ie an autoimmune disease.

Incorrect types or concentrations of good and bad bacteria in the gut or gut dysbiosis can contribute to this process of abnormal stimulation of the immune system. Research supports the strong possibility that such stimulation may be enhanced by the bacteria's interaction with dietary lectins. Some believe this can further worsen intestinal injuries and autoimmune diseases. The latter concept is accepted and recognized by doctors in one form as hygiene theory. It is speculated that our gut bacteria have changed due to increased hygiene and overuse of antibiotics and that this phenomenon may play a significant role in the increasing incidence of autoimmune diseases such as diabetes, arthritis and chronic intestinal diseases such as Crohn's disease and irritable bowel syndrome.

However, lectins as a cause are largely ignored in the United States, although the field of lectinology and the role of lectins in disease is becoming more accepted internationally. Avoiding certain dietary lectins can be helpful in achieving health and healing chronic intestinal injuries. Healing “leaky gut” and preventing persistent abnormal stimulation of the immune system by toxic dietary lectins and bacteria in the gut is the basis for ongoing research and the likely success of several popular diets such as the paleo diet, the carbohydrate-specific diet, and gluten-free/casein-free diets. There is a need for further research in this exciting but often neglected area. The Food Doc, LLC has a website http://www.thefooddoc.com that will provide physician-authored information on food intolerances, sensitivities and allergies such as lectin, gluten, casein and lactose intolerance with nutritional recommendations that will include an online symptom assessment and diet diary in the near future.

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