Why are Lectins considered Toxic?

Lectins are carbohydrate binding proteins found in many foods. Lectins in plants are a defence against micro-organisms, pests, and insects. If an animal eats a lot of the plant it gets digestive disturbances when the sticky lectins bind to the lining of the digestive system. In humans Lectins are resistant to being broken down as part of the digestive process. They are difficult to digest and irritate the brush border of the small intestine.  Consequently, the micro-villi are damaged which can lead to numerous disorders of the gastrointestinal tract and autoimmune diseases. 

Lectins may also be responsible in part for 'leaky gut syndrome'. Plant lectins have been found attached to other organs indicating that some may get through the gut wall. Lectins appear to aggravate existing inflammatory such as rheumatoid arthritis. Lectins are also a major contributor to leptin resistance which contributes to obesity. Foods with high concentrations of lectins, such as beans, cereal grains, seeds, nuts, and potatoes, may be harmful if consumed in excess in uncooked or improperly cooked form. Soaking, sprouting and fermenting helps to break down lectins in food, but much modern food is cooked as quickly as possible, so does not break down the lectins before they are ingested. Some people are also more sensitive to lectins than others.


Immune response and toxicity:

Lectins are thought to play a role in immune function, cell growth, cell death, and body fat regulation. They can promote inflammatory responses such as Crohn’s Disease, systemic Lupus, asthma, rheumatoid arthritis and cause leaky gut and gastrointestinal dysbiosis. Because we do not digest lectins, we often produce antibodies to them. Almost everyone has antibodies to some dietary lectins in their body. This means our responses vary. Some individual can have full blown allergic reactions.

Certain foods can become intolerable to someone after an immune system change or the gut is injured from another source. The presence of particular lectins can stimulate an immune system response. When lectins affect the gut wall, it may also cause a broader immune system response as the body’s defenses move in to attack the invaders. Adverse effects may also include nutritional deficiencies (through damage to the villi in the small intestine). Lectins may also cause leptin resistance, which may translate into diseases, particularly weight loss issues (obesity) in individuals who consume high levels of leptin.


Symptoms can include:

skin rashes, joint pain, and general inflammation. Ingesting lectins can cause flatulence as legumes and grains in their raw form can even result in nausea, diarrhea and vomiting. Indeed, researchers speculate that many apparent causes of bacterial food poisoning may actually be lectin poisoning. Other chronic disorders may be correlated with leaky gut — for example, researchers have even noted that children with autism have very high rates of leaky gut and similar inflammatory GI tract diseases.


Where are Lectins found?

Dairy, Egg, Fruit, Nightshade, Nuts (includes ground nuts), Soya Bean or Wheat. Members of the pea family and include peanuts, pigeon peas, soya beans, kidney beans, mung beans, lima beans, lentils, fava beans, chickpeas, carob, green peas and yellow peas.  Green beans, snow peas and snap peas are usually well tolerated once the gut has been healed since they are immature protein sources with minor amounts of lectins. Genetically modified crops:  wheat, corn, soya beans have high amounts of agglutinin to ensure high yields.

The effects of dietary lectins only extend for as long as they are in the body, and the effects can be reduced by eating a variety of fruits, vegetables (rather than high amounts of one type) and foods with beneficial bacteria (e.g., fermented foods).

Omitting toxic lectins – prolamins and agglutinins – from the diet is critical for gut health.  Prolamins are predominantly found in the seeds of plants.  Gluten is the most widely known source of prolamins; they get their name from the high content of the amino acid proline.  Research studies have shown that the prolamins in quinoa, corn and oats can damage the digestive tract in people with Celiac Disease yet these grains are frequently included in the ‘gluten-free’ diet.  

Our ancestors found a solution to the problem of lectins.

Soaking, fermenting, sprouting and cooking will decrease lectins and free up the good nutrients. The content of lectins in foods differs year to year and crop to crop.


What else do you need to know about Lectins?

  • Grain, cereal, dairy, and legume (especially peanut and soybean) lectins are most commonly associated with reports of digestive complaints.
  • Legumes and seafood are the most abundant sources of lectins in most diets.
  • Certain seaweeds and mucilaginous vegetables have the ability to bind lectins in a way that makes them unavailable to the cells of the gut.
  • Lectins are resistant to dry heat, so using raw legume flours in baked goods should be done with caution.
  • Some experts hypothesize that it’s no coincidence the top 8 allergens also contain some of the highest amounts of lectins (including: dairy, egg, wheat, soy, peanuts, tree nuts, fish, shellfish).
  • Some experts theorize that lectins cause urinary tract infections.
  • Lectins are also a major contributor to leptin resistance which contributes to obesity.
  • Some experts theorize that the reason anaemia is higher in developing countries is due to excessive levels of lectin consumption.
  • research concluded that the glycation reaction seen in Alzheimer’s Disease (AD)  from lectins may serve as a significant factor in amyloid plaque development and disease progression.
  • While many types of lectins cause negative reactions in the body, there are also health promoting lectins that can decrease incidence of certain diseases.

Even though lectins have been identified for decades little interest has been shown by biological and medical science. 

The pressure of plant-based diets focusing on legumes as meat alternatives has overlooked the damage that lectins can cause in the gut. So toxicity of Legumes needs to be considered within food choices.

(Source: https://www.precisionnutrition.com/all-about-lectins)



Testing for Lectins:

We have included testing for Lectins in our Combination Allergy & Intolerance Tests:

Complex 250

Digestion 300 

Comprehensive 500



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