The Collison Newsletter December 2015


                      LECTINS – What are They?

                           Sensitivity to Lectins*   


Lectins are a type of protein that can bind to cell membranes. They are sugar-binding or carbohydrate-binding proteins. They are macro-molecules that are highly specific for sugar moieties (the sugar molecule in a compound sugar portion of a complex molecule).


The Oxford English Dictionary defines Lectin as “Any of a class of protein, chiefly of plant origin, which bind specifically to certain sugars and so cause agglutination of particular cell types”.


Lectins should not be confused with glycoproteins (proteins containing sugar chains or residues), lecithins (fatty substances in animals and plants), or leptin (the hormone that regulates appetite and hunger, metabolism and behaviour).


Traditionally, lectins have been used in biomedicine as histology and blood transfusion reagents, to identify, for example, ABO blood types, and in biochemistry for fractionation.


Lectins perform recognition on the cellular and molecular level and play numerous roles in biological recognition phenomena involving cells, carbohydrates, and proteins. Lectins also mediate attachment and binding of bacteria and viruses, as well as mediate the first-line defence against invading micro-organisms.


Lectins in plants are a defence against micro-organisms, pests and insects. They may also have evolved as a way for seeds to pass through animals’ digestive systems, for later dispersal.


Lectins are resistant to human digestion and they enter the blood unchanged. Lectins are thought to play a role in immune function, cell growth, cell death, and body fat regulation.

Lectins and the Intestinal Wall 

Lectins can bind with carbohydrates in the cell membranes of the cells that line the intestinal wall, causing damage. Sensitive people will develop most commonly, but not limited to, intestinal inflammation, allergies and auto-immune conditions.


When the intestinal wall is inflamed, it becomes damaged, producing more mucous and then the absorption of nutrients is greatly reduced. The balance of gut flora is also significantly affected and yeast infections, candida, and the likelihood of parasites are increased. If the cells are severely damaged, then 'holes' can develop - the leaky gut syndrome. This can allow lectins, undigested food particles and toxins to pass through into the circulatory system and so pass to the whole body. In this way, lectins can attach themselves to organs such as the thyroid, pancreas, kidneys etc, and inflict damage.


Lectins, as found for example in lentils, can bind to insulin receptors on fat cells, sending the same instruction as insulin - which is to make fat. Lectins have been shown to inhibit digestive hormones, such as leptin, that are involved in appetite control which leads to an increase in appetite and obesity. The body may also respond to lectins by attacking them and the tissues to which they are attached - thereby initiating an auto-immune condition.


Digestive enzymes and stomach acid have little effect on lectins.

Lectins in Foods 

Lectins are in all foods, so there is no way to avoid them. However, certain foods have high levels of them. The most common potentially 'toxic' lectin containing foods fall into four groups:

  • All grains including wheat, oats, rye, barley, corn and to a lesser extent millet, wild rice and plain white rice. (Note that buckwheat is not a grain, it belongs to the rhubarb family.) 
  • All dairy products (especially when the cows are feed grains instead of grass) 
  • Legumes, including beans, soy, lentils and peanuts 
  • The nightshade family - potatoes, tomatoes, eggplant, peppers or capsicum.

This includes all foods that are made from the above foods in all forms, such as milled grains, flours, oils, peanut butter, cereals, oils from soy, canola, and corn, thickeners and products containing malt vinegar, as well as beer and ales.

Symptoms of Lectin Sensitivity 

It has been estimated that 40% of the population in the Western World have some level of lectin sensitivity, but only about 25% have it to a level that causes significant discomfort or symptoms. Lectin sensitivity is on a spectrum, where people are sensitive to it in varying degrees. The more symptoms, the higher is the likelihood of lectin sensitivity. These symptoms include:

  • Immune imbalances or any auto-immune condition 
  • Bloating 
  • Gut problems: gas, abdominal discomfort, irritable bowel syndrome 
  • Fatigue, especially post-meal fatigue 
  • Brain fog (see below) 
  • Arthritis 
  • Symptoms due to low serotonin: excessive anxiety, perfectionism, procrastination, paranoia, OCD 
  • Skin problems (not acne): eczema, psoriasis etc 
  • Hypoglycaemia 
  • Joint discomfort 
  • Weight problems 
  • Water retention, with puffiness around the eyes and swelling of the extremities 
  • Headache, migraine 
  • Sleep disturbance 
  • Pain in random places, like back aches (not due to injury).

Some diseases that are thought to be associated with lectins include:

  • Insulin dependant diabetes 
  • Rheumatoid arthritis 
  • IgA nephropathy 
  • Peptic ulcers. 

Brain Fog 

Brain fog comes from inflammation and oxidative stress, particularly in the hypothalamus. Evidence suggests that people with brain fog usually have lectin sensitivity. Lectin sensitivity is almost certain if there are other symptoms that can be linked to lectin sensitivity.


What is brain fog?  It is a term widely used, but there is no set definition for "brain fog" or "clouding of the consciousness". A broad definition is any negative change in cognition that is outside of a normal range for the individual. The most significant type of brain fog is a large drop in cognitive function after eating or at certain times of the day - most commonly in the morning. It usually takes a few hours for each of these episodes to clear, with better functionality albeit not perfectly. Some people experience a chronic type of brain fog.


Reducing the intake of lectins can often lead to complete resolution of the brain fog.

Treatment of (Suspected) Lectin Sensitivity 

There is no way to completely avoid all lectins, as they are in all foods. But it is possible to significantly reduce the intake by completely removing the four groups set out above, or at least minimising their intake.


Once improvement is apparent, carry out a cautious re-introduction of one food group at a time, looking for a return of symptoms. It may be that only one member of, say, the nightshade family, for example tomato, is the main culprit. When such a food is identified, it should then be excluded completely from the diet.


It may take days or even weeks for the symptoms to reduce or go completely. It is important to "listen to your body". Exclude, monitor how you feel, noting any reduction in symptoms and their recurrence when the excluded food is reintroduced into the diet.


This is a similar approach to the diagnosis of food intolerance as described in detail in my book How to STOP Feeling So Awful (see home page). In brief, a suspect food is excluded for 10 days, and then reintroduced as a single test food, monitoring for a return of symptoms.

Is it Possible to Reduce or Neutralise Lectins? 

The lectins in foods may be inactivated, at least partially, by soaking, sprouting, cooking, or fermentation.

  • Soaking

The term legume embraces beans of all types including soy, chickpeas, lentils and peanuts. Soaking legumes overnight, rinsing thoroughly and changing the water several times, then draining and giving a final rinse before cooking, seems to remove or inactivate many of the lectins present.

  • Sprouting

Sprouting seeds, grains, and beans decreases the lectin content. Generally, the longer the duration of sprouting, the more the lectins are deactivated. The lectins in some grains and beans are in the seed coat. As it germinates, the coat is metabolised - eliminating the lectins. A paradox, it seems that sprouting alfalfa could increase lectin activity!

  • Cooking

Heating may remove or reduce lectins in some foods, but not all.

  • Fermentation

Fermentation allows beneficial bacteria to digest and convert and inactivate many of the harmful substances, including lectins.

Fermented soy products include:

  • Natto
  • Miso
  • Tempeh
  • Soy sauces
  • Fermented tofu
  • Soy milk.

Cultures with a history of grain eating traditionally have used some form of fermentation to treat grains. Sourdough bread and beer have fermented grains.

Note that not all lectins are completely destroyed by these methods, and some particularly stubborn lectins in beans remain no matter how lengthy the treatment. Thus, these techniques do not totally reduce the negative effects for everyone.


It has been argued that since agriculture is a relatively recent invention, humans did not evolve to tolerate grains or beans well.


Since lectins are so widely distributed in food items commonly consumed by humans, and have been for centuries, it is assumed by some nutrition experts that they do not pose a significant risk to human health.


Clinical experience, however, clearly demonstrates that the chronic ingestion of untreated high-lectin foods can be responsible for a spectrum of symptoms and ill health in some (susceptible) people.

When the above spectrum of symptoms are present, lectin sensitivity should be considered as the cause. Therapy will include avoidance of the high lectin-containing foods and/or reducing the amount of lectins by soaking, sprouting, fermenting and/or cooking.


*Copyright 2015: The Huntly Centre.

Disclaimer: All material in the website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.

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