What are lectins? Should I avoid foods containing them?

What are lectins? Should I avoid foods containing them?
Weight loss, better digestion, relief from allergies, leaky gut IBS, and autoimmune conditions are all symptoms and conditions that could theoretically be side stepped if you remove lectins from your diet. But is it worth it? Should you really be afraid of lectins?

Spoiler alert: We don’t think you should be afraid of any type of food that exists in nature—but we have developed a way to maximize the nutritional benefit of foods that contain lectins while limiting the damage they may cause.

First thing’s first—what are lectins?

Lectins are a type of plant protein that can be found in almost all foods, but the foods that are believed to be highest in lectins include whole grains and legumes, and nightshade vegetables, like tomatoes, peppers and potatoes.

There are many different types of lectins, which have different functions in the body. Some lectins can make plant foods difficult to digest—the most extreme example is phytohaemagglutinin, the lectin that causes raw kidney beans to be toxic to humans.

Other types of lectins, like those found in tomatoes, are believed to cause inflammation and make arthritis more painful (although this hasn’t been proven).

Lectins have recently become villainized because of some claims that they can make our cells stick together, leading to inflammation, weight gain, unpleasant digestive symptoms, and intestinal permeability (also known as “leaky gut”). But these anecdotal accounts have never been substantiated in published studies.

Could cutting lectins from your diet reduce unpleasant digestive symptoms? Possibly. But cutting lectin-containing foods could also mean that you’re missing out on some of the essential nutrients contained in them that are critical for your health.

Not much research on lectins

Since the 1970s, there have been some studies on lectins, but they are mostly in vitro (test tube) or animal studies that are hard to translate to human nutrition.

Most of the information on the effects that lectins have on the body is anecdotal—some people report that giving up lectins has helped them lose weight, or reduced digestive upset.

But there are no long-term studies that show how removing all of the lectin-containing foods will affect your health in the long term. There just isn’t enough research on the lectin-free diet at this point.

The Mediterranean Diet, however, is supported by lots of research. It’s the most studied diet for heart health and other inflammatory conditions. And some of the most-consumed foods on the Mediterranean Diet happen to be high in lectins, like whole grains and legumes, and nightshade vegetables like tomatoes and peppers—so it appears that foods that contain lectins must have some health benefits.

 Health benefits of lectin-containing foods

 Cutting foods that contain lectins from your diet would mean that you’re missing out on important nutrients. Here are just a few examples:

  • Tomatoes are members of the nightshade family and are therefore banned on a lectin-free diet. But if you avoid eating tomatoes, you’re missing out on some of their beneficial nutrients like lycopene—which has been shown to protect the prostate, but also has other far ranging benefits, like promoting heart health, and contributing to healthy skin by helping to clear free radical damage caused by sun exposure.

  • Squashes and pumpkins are also a lectin-free diet no-no, despite containing a range of phytonutrients with strong antioxidant activity. Both squash and pumpkin also appear to be beneficial for a healthy intestinal ecosystem, despite containing lectins, which are supposedly bad for the gut.

  • Legumes, banned on a lectin-free diet as well, are a valuable source of protein and provide a wide variety of healthy phytochemicals. Nations with high intake of legumes have low rates of colon cancer. Plus, many studies in animals and other experimental settings support the gut-protective properties of legumes[1].

Another study showed that when added to an omnivorous diet, fully cooked black and navy beans have a positive influence on the gut microbiome, can increase the production of critically important short chain fatty acids, and protect against intestinal permeability[2].

The bottom line: Lectin-containing foods have clear, research studied health benefits, so we should include them in our diet.  

So what now?

Since lectins are contained in foods that have been shown to be very beneficial for your health, it doesn’t make sense to cut every food that contains lectins from your diet.

We think it makes more sense to eat a broad range of healthy foods, and to reduce the impact that lectins may have through food preparation methods.

  • Heat destroys lectins, so if you’re going to eat a pot of beans, grains or legumes, it is a logical common practice to cook them first.

  • Another way to reduce lectins is by soaking your grains or beans in water (also called sprouting, or open fermentation) before cooking them. Sprouting for up to 48 hours can reduce lectins by around 20%.

But there’s an even better way to remove lectins from grains, beans and legumes. It’s a process that can reduce lectins by up to 99.99%[3],[4].


The fermentation process is incredible. We got really interested in fermentation 5 years ago when we were sitting around the product development table, talking about what was happening in the field of nutrition. The common theme was that people were starting to avoid foods like dairy, soy and gluten.

We realized that the real problem wasn’t these foods. The problem was that as a nation, we have poor gut health—which is causing us to become sensitive to some of the foods that we commonly eat.

So we set out to use fermentation to help solve digestive issues—and we discovered some other amazing things.

Fermentation can release the nutrients and health benefits in food, providing antioxidant and anti-inflammatory properties[5]. Fermentation can also provide gut protective-benefits, thanks to bioactive nutrients and postbiotics formed in the fermentation process. (And fermentation can remove lectins, too[6].)

We used all of these discoveries to bring the first fermented protein to market. fermented organic vegan proteins+ is thoughtfully formulated with 7 protein-rich plant foods, including hemp seeds, brown rice, pea, mung beans, spirulina, flaxseed and pumpkin—to provide 20 grams of highly absorbable protein with added gut health benefits thanks to bioactive nutrients and postbiotics.

To recap:

  • Lectins in some foods could potentially aggravate the gut, but we can’t be sure because there are no human studies.

  • Avoiding dietary lectins is not the solution, as many of the foods with the highest lectin content contain unique nutrients that are essential to our health. Food preparation methods like fermentation to reduce or entirely remove lectins from foods.

  • Our favourite technique (by far) is fermentation, because it not only removes anti-nutrients and makes the protein easier to digest, but creates entirely new nutrients that are beneficial for gut health. Yes, you can have your lectins—and eat them, too!



[1] Sanchez-Chino X, et al. Nutrient and non-nutrient components of legumes and its chemopreventive activity: a review. Nutr Cancer 2015;67:401-10.
[2] Monk JM, et al. Navy and black bean supplementation primes the colonic mucosal microenvironment to improve gut health. J Nutr Biochem. 2017 Nov;49:89-100
[3] Difo VH, et al. Changes in nutrient and antinutrient composition of Vigna racemosa flour in open and controlled fermentation. J Food Sci Technol. 2015 Sep;52(9):6043-8
[4] Cuadrado C, et al. Effect of natural fermentation on the lectin of lentils measured by immunological measures. J Food Agric Immunol 2002;14:41-49
[5] Gabriele M, et al. A fermented bean flour extract downregulates LOX-1, CHOP and ICAM-1 in HMEC-1 stimulated by ox-LDL. Cell Mol Biol Lett. 2016 Aug 12;21:10
[6] Zárate G, et al. Dairy propionibacteria prevent the proliferative effect of plant lectins on SW480 cells and protect the metabolic activity of the intestinal microbiota in vitro. Anaerobe. 2017 Apr;44:58-65

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