Lectins, the Evil Protein

  I am not a doctor – so I can’t help you with any medical advises. For these you will need to consult your doctor. But you will find (on the bottom of each page) medical articles on which I based my information. My advise is that after you read the information I presented – to print the references and have a discussion with your doctor.

  While I can’t help you medically, I am a certified Life Coach and Professional Engineer (PEng). So I can counsel and encourage you in taking the best decisions in your personal life.


  So, you may ask: what is this thing – lectins.

Lectins are a type of protein that can bind to cell membranes. They are sugar-binding and become the “glyco” portion of glycoconjugates on the membranes. Lectins offer a way for molecules to stick together without getting the immune system involved, which can influence cell-cell interaction.

  Lectins in plants are a defense against microorganisms, pests, and insects. They may also have evolved as a way for seeds to remain intact as they passed through animals’ digestive systems, for later dispersal. Lectins are resistant to human digestion and they enter the blood unchanged.

  Most plants do not want to be eaten, so having these damaging molecules may discourage animals from eating them in large amounts. Just like other animals, humans are vulnerable to the toxicity of lectins. Concentrated amounts can cause digestive issues and long-term health problems. In the case of the poison ricin (a lectin from the castor oil plant), they can even cause death.

  But why are so dangerous (see reference 2):

  • Locally, they can affect the turnover and loss of gut epithelial cells, interfere with nutrient digestion and absorption, stimulate shifts in the bacterial flora and modulate the immune state of the digestive tract.
  • Systemically, they can disrupt lipid, carbohydrate and protein metabolism, promote enlargement and/or atrophy of key internal organs and tissues and alter the hormonal and immunological status.

  The “stickiness” of lectins makes them prone to attaching to the intestinal wall. There, they disrupt the body’s routine maintenance of cells, so the everyday wear-and-tear that occurs in the intestine gradually worsens. This is the main reason why excessive lectin intake causes digestive distress.

  Repeated exposure to lectins may eventually damage the gut wall. Unwanted substances can then more easily penetrate the gut, and may enter the bloodstream.

  Lectins can also interact with antibodies, which are a core component of the immune system. This may cause an immune reaction not only against the lectins, but also the body tissues to which the lectins are bound. This type of response is known as an autoimmune reaction, where the immune system mistakenly starts attacking the body’s own structures. This is how lectins may increase the risk of autoimmune diseases.(see reference 4)

Foods containing high 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.

  The most potentially ‘toxic’ lectin containing food groups are:

  • grains, especially wheat and wheat germ but also quinoa, rice, buckwheat, oats, rye, barley, millet and corn
  • legumes (all dried beans, including soy and peanuts)
  • dairy (perhaps more so when cows are feed grains instead of grass, a speculation based on research showing transference of lectins into breast milk and dairy
  • nightshade (includes potato, tomato, eggplant and pepper)

  Dairy may be potentially more harmful in pasteurized, processed milk (see reference 5). That is why only breast milk is good for babies.

  Of course potentially ‘toxic’ are also all foods made from these substances, (these substances in all forms, milled grains, flours, oils, malt vinegars), peanut butter, cereal, or legume oils (soy, canola, corn), additives, thickeners and products containing malt vinegar, as well as beers and ales. Grape based alcoholic beverages and DISTILLED grain based alcohols are allowed if you know you tolerate them.

  You will find information out there that lectins may be inactivated by soaking, sprouting, cooking or fermenting. Soaking legumes over night, draining the water, rinsing and draining again does seem to remove or inactivate many of the lectins. Heating seems to remove others in some foods but not all. There is little data to prove that any of these methods remove lectins completely as few foods have been tested and of those that have lectins many seem to remain after processing.

  According to Nachbar and Oppenheim (see reference 6) found 30% of fresh and PROCESSED foods contained active lectins. Lectins from green salads, fruits, spices, seeds, dry cereals and nuts (even after roasting) showed activity of potentially toxic lectins. Some of these lectins interact with serum or salivary components and bacteria from the oral cavity according to Gibbons & Dankers (see reference 5).

Possible solutions

  According to Allergist David Freed (see reference 1) consuming simple sugars and oligosaccharides (inulin) can block the effects of lectins.

  Also, an Elimination Diet can help with identifying the foods that you may react the worst. Elimination Diet looks like this:

  Remove all suspect lectin families (legumes, dairy, etc) for 7 days. Make sure to read labels so that you aren’t consuming a part of the lectin family hidden in a food. On day 8 reintroduce several of the family members, such as, if testing dairy, milk, cheese and sour cream or legumes, soy, kidney bean and peanut butter. Eat some of the family at each meal. Stop all of the family for the next two days. That is 7 days off, one day on and 2 days off. Check your symptoms on the day of testing and the following 2 days. Look for changes in energy, appetite, bowel function, mood, sleep, skin, digestion, anything suspicious. Test only one ‘family’ at a time. You may remove as many groups as you feel are suspect but only reintroduce one family at a time. If you find you must eliminate one or more lectin families retest every six months to see if the intolerance is genetic or induced.

  So, sounds REALLY BAD. And the truth is that it is really, really bad considering our modern lifestyle. Almost all the population today can check one or even more of the features of the modern lifestyle directly contribute to unhealthy gut flora that I listed on page Gut Health and Inflammation.

  But I know none of us can really renounce to all the foods containing lectin. I found myself that if you use a combination of the 2 techniques: inulin and elimination diet – you can figure out a lot of foods containing less lectin that can be almost completely neutralized by inulin. You may even enjoy inulin itself as you can use it instead of sugar. So, you don’t need to give up completely everything you enjoy. But is good to totally avoid foods that you find trigger bad reaction in you, and to enjoy with moderation (and add inulin in your pantry) the once that don’t give you too much trouble.

  I will also mention that diets (lifestyle) like Paleo and Keto tend to avoid exactly the foods high in lectin. Maybe that is the reason they work for so many people. Hopefully some research will be done to confirm this fact.

1. David L J Freed US National Library of Medicine 1999 Apr 17 Do dietary lectins cause disease?
2. Vasconcelos IM, Oliveira JT US National Library of Medicine 2004 Sep 15 Antinutritional properties of plant lectins.
3. Katsuya Miyake, Toru Tanaka, and Paul L. McNeil US National Library of Medicine 2004 Sep 15 Lectin-Based Food Poisoning: A New Mechanism of Protein Toxicity
4. Cordain L, Toohey L, Smith MJ, Hickey MS US National Library of Medicine 2004 Sep 15 Modulation of immune function by dietary lectins in rheumatoid arthritis.
5. Davin JC, Senterre J, Mahieu PR US National Library of Medicine 2004 Sep 15 The high lectin-binding capacity of human secretory IgA protects nonspecifically mucosae against environmental antigens.
5. R. J. Gibbons and I. Dankers American Society for Microbiology Lectin-Like Constituents of Foods Which React with Components of Serum, Saliva, and Streptococcus mutans
6. Nachbar MS, Oppenheim JD US National Library of Medicine 1980 Nov Lectins in the United States diet: a survey of lectins in commonly consumed foods and a review of the literature.
7. Klurfeld DM, Kritchevsky D US National Library of Medicine 1980 Nov Isolation and quantitation of lectins from vegetable oils.