Lectins: what they are, and how to deal with them

Edible Seeds

By Cat, Feb 22 2019 (Image, right, from Fit Element (1))

The most common lectins are toxic, sticky, carbohydrate-binding proteins originating in plant foods, but can also be found in dairy and eggs from animals fed soy/grain diet. There are also non-toxic animal-source lectins which have specific benefits for the animal.

They are highly specific for sugar moieties. They have behaviors in common with antibodies but are not antibodies. The toxic lectins can cause damage to the lining of your gastrointestinal tract or your organs, and interfere with metabolism when consumed in large amountsFor example, the deadly toxin, “ricin” is made from lectins in castor beans and black beans.

Lectins are needed by plants to preserve the species; lectin toxicity keeps spiders, insects, birds, rodents and other animals – including humans – from eating un-sprouted seeds by making them sick. The process of germination begins to break down the lectins, removing the toxicity. By the time the young sprout produces its first leaves, the lectins are all gone until the plant’s blossom produces new seeds.

There are also animal-source lectins which have specific benefits

How can you avoid the harm of lectins and still eat these foods? Read on…

The harm of toxic lectins

Note: While most lectins have some level of toxicity, there are a few lectins that actually provide benefits, when consumed in small amounts. See “Safe and/or beneficial lectins,” below.

For a good list of plant foods that contain lectins, see Livestrong article (8). Certain plant foods have the most difficult lectins in their seeds: grains, legumes, nightshades; for example (2):

  • legumes (includes peanuts and cashews as well as dried beans);
  • all grains (wheat, oat, rice, etc.);
  • seeds from all nightshades (tomatoes, eggplant, peppers) and also potato tubers;
  • tree nuts and most seeds; and also
  • milk, dairy and eggs from animals fed grains and soy.

Dr Gundry lists 4 lectin risks (2):

  1. Damage to gut & inability to digest food – can’t metabolize proteins or carbs efficiently;
  2. Leaky Gut syndrome and auto-immune diseases. Their sticky nature allows them to stick to the walls of the intestines and cause leaky-gut (by widening the space between the cells of the cell wall so that other substances that are not fully digested can pass through into the blood stream where they can cause significant damage including auto-immune diseases). (5A)
  3. Increase appetite. When they stick to and block insulin receptors, this leads to insulin resistance (hypoglycemia, precursor to type-2 diabetes, metabolic syndrome, and more). Wheat germ lectin (WGA) is one of the worst.
  4. Damage blood vessels – endothelial dysfunction – which can lead to heart disease.

Avoiding toxic lectins

Certain plant foods have the most difficult lectins in their seeds: grains, legumes, nightshades. The best solution to minimize these lectins is to soak or sprout the seeds before eating them. Cooking – especially in a pressure cooker (for legumes) can often destroy lectins.

If eating tomatoes, peppers or eggplant, especially raw or light cooking, remove the seeds before eating/cooking, if you don’t want to sprout them.

  • First, it’s important to know which are beneficial or at least not harmful, and which are toxic. The 3 most important foods to avoid: soy, tree nuts & eggplant. (2)
  • Sprouting nuts/seeds is best way to avoid their toxic lectins, as sprouting breaks them down. Fermenting them (e.g., sourdough grains) also breaks down the lectins.
  • Avoid products from animals fed a soy/grain diet; for example, commercial eggs, meats and dairy. Instead, buy from local farmers/ranchers you trust.
  • Even milk from pastured livestock contains lectins designed to keep other animal species from drinking the milk while not harming their own offspring. But less is known about animal lectins than plant lectins. (7) I don’t know if culturing milk breaks down these animal lectins.
  • Coconuts also contain lectins, but I am still researching this, as to whether they are toxic lectins for humans.

Dr Gundry says you can give up all lectin foods, but while this does work for awhile, the patient eventually relapses. Also, it is hard to do if eat out. (2)

Anti-Lectin supplements

What to do when you eat out or don’t have the time to sprout or ferment the seeds, or remove them from fruits and vegetables?  You can take supplements that:

  • bind/block lectins, or
  • help with the pain/discomfort caused by specific lectins.

Mono- and oligo-saccharides are the most commonly used for this purpose. [Mono-saccharides are single sugars like glucose and mannose; oligo-saccharides are short chains of sugars that fall into the category of “fiber.”]

The following list is what comprises Dr Gundry’s supplement, “Lectin Shield” (or you can take them separately, which is what I do):

  • Lectin Shield ingredients:
    • MSM (methylsulfonylmethane)
      (contains sulfur so if you have a problem with sulfur foods, you need to avoid this. It is problematic for me);
    • D-mannose (a mono-saccharide, and cousin of glucose) binds/blocks lectins in legumes. It is found in cranberries, blueberries, apples, peaches, and oranges (2,3), and is beneficial for urinary tract health.
    • Sialic acid (Mucin) which binds & blocks lectins in grains & berries; for example, Sialex supplement on Amazon (ASIN B003TVEZ9O). Mucilagenic foods/supplements, such as marshmallow root, okra, and slippery elm, coat the intestines and keep the lectins from binding
    • N-Acetyl D-Gulcosamine, also called NAG (some call it NAD, but that is not as common), helps with joint discomfort caused by wheat lectins (but I don’t know if it blocks them). It is also a precursor to hyaluronic acid. See iHerb codes: ARG-51140 or JRW-19002);
    • Bladderwrack (from seaweed), provides iodine and blocks inflammatory lectins in many foods. Also has anti-fungal properties, for example, to help keep candida in check;
    • Dr Gundry’s  supplement also includes items that are not anti-lectin: Okra, larch arabinoglactans, sodium alginate, & vegetable peptidase.
  • Benefits of these anti-lectin ingredients:
    • Reduces gas, bloating, etc.
    • Controls cravings for unhealthy foods
    • Reduces appetite to retain healthy weight
    • Strengthens joints & muscles
    • Allows body to absorb more nutrients to boost energy
    • Improves immune system protection
    • Strengthens walls of gut
    • More regular bathroom habits.

What I am doing to reduce exposure to toxic lectins (by Cat):

  • Legume, grain, tree-nut and seed lectins: I soak and preferably sprout them prior to eating them, unless I will only be eating a very small quantity. In the case of nuts, after soaking/sprouting, I also toast them. See: Soaking, Sprouting and Fermenting Grains, Nuts, Seeds and Legumes Menu for instructions.
  • Legume lectins: A couple years ago, I started adding D-mannose (the sugar in cranberries) to my morning smoothie because I tend to get bladder infections; and now I know it also binds legume lectins. I also soak legumes for 12 hours or more before cooking, and bring soaked kidney beans to a boil before simmering them.
  • Nightshade lectins: I remove seeds from tomatoes, peppers and eggplant, and I cook potatoes to reduce their lectin content by 50-60% (5).
  • Cucubita lectins: I remove the seeds from squash, pumpkin, watermelon, cantaloupe and summer squash (such as zucchini). Because I love toasted pumpkin seeds, I soak and then toast them.
  • Wheat lectins: I use sprouted wheat for baking breads, etc. (from Granite Mill Farms in Trout Creek, MT (6)). I used to take N-A-D supplement to help with joint discomfort, but stopped when I learned it can make insulin resistance worse.
  • Grain and Berry lectins: I am looking into sialic-acid (mucin) supplements.

Safe and/or beneficial lectins:

Safest plant foods, in terms of lectin content, are:

  • asparagus,
  • garlic, celery,
  • mushrooms, and
  • onion family.

Other excellent choices that can be eaten without restrictions are (See my reference for Mercola’s article 5A, for his superscript reference numbers: 25, 26, and 27):

  • Cooked tubers (root vegetables) such as sweet potatoes, yucca and taro;
  • Leafy greens; however, many have phytates that bind the minerals so you can’t absorb them when raw (braising or lightly sautéing them in oil helps with that);
  • Cruciferous vegetables such as broccoli, cabbage, cauliflower, kale and Brussels sprouts;
  • Avocados: “while avocados contain high amounts of lectins,25 these lectins are safe and healthful. Research26 shows that the specific type of lectin found in avocado, persea Americana agglutinin,27 is devoid of specificity for carbs; it interacts with proteins and polyamino acids instead.” (5A) In other words, they bind to proteins and peptides instead of sugars/starches.
  • Olives and authentic extra-virgin olive oil.


  1. Image of edible seeds: fitelement.com/the-difference-between-grains-and-seeds/
  2. Dr Gundry’s “Lectin Shield” links:
    1. Dr Gundry’s “Lectin Shield” sales pitch: lectinblocker.com/?n=db
    2. About Lectin Shield: gundrymd.com/supplements/lectin-shield/
    3. Dr Gundry’s special price-deal
    4. see also Mercola’s article below (5), which includes a video conversation with Dr. Gundry
  3. Benefits of d-mannose: .organicfacts.net/d-mannose.html, by John Staughton (BASc, BFA)
  4. Dr. Smith’s Lectins – Natural toxins in food: articles.healthrealizations.com/CrabappleInternalandIntegrativeMedicine/2014/09/01/Dr–Smith-s-Lectins—Natural-Toxins-in-Food.aspx
  5. Mercola:
    1. Reduce Lectins in your Diet: articles.mercola.com/sites/articles/archive/2017/08/14/reduce-lectins-in-your-diet.aspx; includes his references:
      1. 25 Superfoodly, 50 Foods
      2. 26Science.gov, Records for Persea Americana; and
      3. 27 Superfoodly, 50 Foods High in Lectins
    2. How to reduce lectins in your diet (5B);
    3. How fasting and minimizing lectins can benefit your health (5C)
  6. granitemillfarms.com/products.htm
  7. superfoodly.com/foods-high-in-lectins
  8. Livestrong:
    1. Foods that contain lectins: livestrong.com/article/305368-list-of-foods-that-contain-lectin/
    2. Lectin-Avoidance diet:  livestrong.com/article/302561-a-diet-for-b-positive-blood-group/ (8B)
  9. Dr Alan Christianson with Dr David Katz: youtube.com/watch?v=v42Xue0BNsY

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