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Could This Plant Protein Cause Autoimmune Disease, Brain Dysfunction and Diabetes?

lectins, plant proteins

By Kelley Herring

For years we’ve been told that a plant-based diet is the cure-all-prevent-all for chronic disease.

The truth is, there are many compounds in “plant foods” that can seriously harm your health. In fact, they can actually cause disease in some people.

Among these are compounds known as lectins – a type of protein found primarily in plants (especially raw grains and legumes).

What are Lectins?

Lectins are molecules that protect plants from microorganisms, pests, insects and other predators. They actually help prevent plants from being consumed – and that includes by YOU!

Lectins also resist digestion and pass through the tract unchanged (a survival mechanism for seeds).

Lectins pose a threat to your health because they have the potential to damage the gut. This can trigger inflammation and a host of symptoms that can be difficult to diagnose and treat.

Though most medical professionals are aware of gluten intolerance and celiac disease, very few realize that lectins have the potential to enhance these and other food sensitivities.

Lectins Resist Digestion, Interfere With Metabolism, and Alter Gut Function

Because lectins can withstand heat and digestion in both animals and humans, they have been shown to interfere with metabolism and alter gut function.

From the British Journal of Nutrition:

“As a result of their binding by the epithelial cells of the small intestine, all three lectins were growth factors for the gut and interfered with its metabolism and function to varying degrees.”[i]

Furthermore, studies have shown that a certain type of dietary plant pectin, called wheat germ agglutinin (WGA):

May alter intestinal epithelial or bacterial cell function in the human bowel.[ii]

Lectins Promote Leaky Gut Syndrome & Alter the Microbiome

When your gut is “leaky” it means the lining of your digestive system has become porous. This allows bits of undigested food, bacteria, viruses and yeast to enter the bloodstream, where they wreak havoc on our health.  Leaky gut syndrome is one of the most common (and overlooked) causes of allergic, inflammatory and autoimmune conditions.

Each time food passes through the gut, it causes a bit of damage to the lining of our GI tract. Under ordinary circumstances, our cells repair this damage quickly. However, lectins deaden this reconstruction and slow this vital process to a crawl. When cells are unable to regenerate fast enough to keep the lining of the intestine intact, the result is leaky gut syndrome.

Left unchecked, this alters gut microbiota and leads to gut dysbiosis (an overgrowth of bad bacteria and a reduction of beneficial bacteria). Leaky gut syndrome can also cause small intestinal bacterial overgrowth (SIBO).

In SIBO, bacterial overgrowth in the small intestine interferes with normal digestion and absorption. In other words, many of the nutrients you consume are metabolized by bad bacteria before the rest of your system has a chance to benefit!

According to a study published in Antinutrients and Phytochemicals in Food:

“By virtue of their ability to bind glycoproteins in the small intestine, lectins lead to an interference with the absorption of nutrients.”[iii]

Because lectins interfere with the regeneration of the gut lining, the body must concentrate energy on healing the injured gut lining over and over, redirecting proteins and other resources from basic growth and repair processes.

This cycle of continuous damage is another reason lectins leave us susceptible to developing chronic disease.

Meats with B-Vitamins

Lectins Stimulate the Immune System and Trigger Inflammation

Lectins also reduce intestinal heat shock proteins (iHSPs), important anti-inflammatory proteins vital for healthy interaction with gut bacteria.[iv]

Animal studies show that dietary lectins also increase gut levels of E. coli and Lactobacillus lactis. These bacteria have proteins similar to HLA (human leukocyte antigen) and are associated with autoimmune diseases such as rheumatoid arthritis. [v]

As lectins are absorbed into the bloodstream, we develop antibodies against them. This increases the likelihood of food allergy and autoimmune disease development.[vi]

What’s more, because lectins open your gut lining they can cause an immune or allergic response to a host of unrelated foods.

For example, according to a study published in the British Journal of Nutrition, rats fed with wheat germ agglutinin and egg protein developed a stronger antibody response than when they were fed egg white protein alone.

The study concludes that “high dietary intake of lectins may affect the allergic response to oral antigens in the gut-associated lymphoid tissue”.[vii]

This may account for multiple food and chemical allergies “springing up” within a short span of time.

Lectins May Promote Obesity and Diabetes

A study published in The American Journal of Physiology showed that the lectin wheat germ agglutinin (WGA) produces “several alterations in the ability of fat cells to bind and respond to insulin.”

Lectins have also been associated with a pre-diabetic condition linked to obesity called ‘leptin resistance’.[viii]

Leptin is a hormone produced by fat tissue and is responsible for regulating our appetites. When our appetites are not properly regulated by this hormone, it is easy to overeat because our brains don’t get the “I’m full” message!

Lectins May Interfere With Mood and Healthy Brain Function

Although inflammation and exhaustion both play a strong role in nervous system dysfunction in chronic illness, medical professionals continue to overlook important factor: Lectins.

According to a 2016 study published by Frontiers in Nutrition, lectins were found to reduce dopamine-containing neurons and alter the size of neurons.

Dopamine has been called our “motivation molecule”. Low dopamine levels can lead to lack of motivation, fatigue, addictive behavior, mood swings, depression and memory loss.

What’s more, researchers found that lectins appear to be transported from the gut along nerve cells where they inhibit dopamine-producing neurons. By this mechanism, lectins may contribute to the development of Parkinson’s disease.[ix]

How to Get Lectins Out of Your Life!

Consume an ancestral diet. This will go a long way toward protecting you from the risks of lectins. But even some Paleo foods are chock-full of these damaging compounds.

Stay tuned! In the next article, I’ll show you high-lectin foods to avoid, an easy way to gauge your sensitivity and four culinary techniques to help reduce your exposure.

kelley herring

Kelley Herring

Cook healthier meals in a fraction of the time with Kelley’s newest program Instant Pot Keto. Inside you’ll discover 100+ ketogenic recipes made with the magic of the Instant Pot, all designed to provide superior nutrition and metabolic balance. Get your copy of Instant Pot Keto today!


[i] Pusztai A, Ewen SW, Grant G, et al. Antinutritive effects of wheat-germ agglutinin and other N-acetylglucosamine-specific lectins. Br J Nutr. 1993;70(1):313-21.

[ii] Brady PG, Vannier AM, Banwell JG. Identification of the dietary lectin, wheat germ agglutinin, in human intestinal contents. Gastroenterology. 1978;75(2):236-9.

[iii] Liener, I E, Plant Lectins: Properties, Nutritional Significance, and Function. Antinutrients and Phytochemicals in Food. 1997; Chapter 3, pp 31–43.

[iv] Lallès J-P. Microbiota-host interplay at the gut epithelial level, health and nutrition. Journal of Animal Science and Biotechnology. 2016;7:66. doi:10.1186/s40104-016-0123-7.

[v] Banwell JG, Howard R, Kabir I, Costerton JW. Bacterial overgrowth by indigenous microflora in the phytohemagglutinin-fed rat. Can J Microbiol. 1988;34(8):1009-13.

[vi] Cordain L, Toohey L, Smith MJ, Hickey MS. Modulation of immune function by dietary lectins in rheumatoid arthritis. Br J Nutr. 2000;83(3):207-17.

[vii] Watzl B, Neudecker C, Hänsch GM, Rechkemmer G, Pool-zobel BL. Dietary wheat germ agglutinin modulates ovalbumin-induced immune responses in Brown Norway rats. Br J Nutr. 2001;85(4):483-90.

[viii] Jönsson T, Olsson S, Ahrén B, Bøg-hansen TC, Dole A, Lindeberg S. Agrarian diet and diseases of affluence–do evolutionary novel dietary lectins cause leptin resistance?. BMC Endocr Disord. 2005;5(1):10.

[ix] Zheng J, Wang M, Wei W, et al. Dietary Plant Lectins Appear to Be Transported from the Gut to Gain Access to and Alter Dopaminergic Neurons of Caenorhabditis elegans, a Potential Etiology of Parkinson’s Disease. Frontiers in Nutrition. 2016;3:7. doi:10.3389/fnut.2016.00007.