Are Lectins Bad For You?

Lectins have been whirring around health circles for a while now, particularly among paleo enthusiasts. They have been dubbed as inflammatory, toxic and a contributing factor to autoimmune disease, obesity and more. But is there any science behind these claims? I took a look.

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What Are Lectins?

Lectins are carbohydrate-binding proteins believed to help plants ward off harmful bacteria. Essentially, they help plants stay disease-free just like some of our immune defenses protect us. Our bodies cannot digest lectins and consuming large amounts of raw lectins can lead to nausea, vomiting and diarrhea. Cellular and animal studies indicate that lectins may trigger an immune response [1,2].


Where Are Lectins Found?

Lectins are found in food such as beans, wheat, soy, tomatoes, nuts, potatoes and bananas. However, the lectin content of these foods is largely destroyed with cooking, and reduced with sprouting and fermentation.


Research On Lectins

Few studies indicate that the lectins are strongly implicated in ill health in humans. Eating raw kidney beans has been linked with gastro symptoms, but when was the last time anyone did that? Personally, I prefer my beans cooked.

Yes, some cell and animal studies indicate that lectins may be inflammatory, activate the immune system and damage the gut mucosa but the evidence in humans in sparse [1,2]. Many things in our environment stimulate the immune system and it isn’t always bad. On the contrary, some lectins are being investigated as novel therapies for cancer, and viral illnesses [3,4].


Should You Avoid Lectins?

Unless you have a particularly bothersome reaction to grains, legumes, and other lectin-containing foods, there’s no need to go lectin-free. In fact, if you remove lectins from your diet you may miss out on important nutrients like fiber, B vitamins, and potassium. Furthermore, studies suggest that consuming a wide range of whole grains, legumes and vegetables may help ward off diabetes, prevent some forms of cancer, and maintain a healthy weight [5,6].


[1] Do dietary lectins cause disease? : The evidence is suggestive—and raises interesting possibilities for treatment David L J Freed BMJ. 1999 Apr 17; 318(7190): 1023–1024.PMCID: PMC1115436

[2] The Dietary Intake of Wheat and other Cereal Grains and Their Role in Inflammation. Karin de Punder, Leo Pruimboom. Nutrients. 2013 Mar; 5(3): 771–787. Published online 2013 Mar 12. doi: 10.3390/nu5030771. PMCID: PMC3705319

[3] Plant Lectins as Medical Tools against Digestive System Cancers. Laura Elena Estrada-Martínez, Ulisses Moreno-Celis, Ricardo Cervantes-Jiménez, Roberto Augusto Ferriz-Martínez, Alejandro Blanco-Labra, Teresa García-Gasca. Int J Mol Sci. 2017 Jul; 18(7): 1403. Published online 2017 Jul 3. doi: 10.3390/ijms18071403.

[4] Anti-tumor and anti-viral activities of Galanthus nivalis agglutinin (GNA)-related lectins. Wu L, Bao JK. Glycoconj J. 2013 Apr;30(3):269-79. doi: 10.1007/s10719-012-9440-z. Epub 2012 Aug 15. Review. PMID:2289311.

[5] Putting the Whole Grain Puzzle Together: Health Benefits Associated with Whole Grains—Summary of American Society for Nutrition 2010 Satellite Symposium. Satya S. Jonnalagadda, Lisa Harnack, Rui Hai Liu, Nicola McKeown, Chris Seal, Simin Liu, George C. Fahey. J Nutr. 2011 May; 141(5): 1011S–1022S. Published online 2011 Mar 30. doi: 10.3945/jn.110.132944. PMCID: PMC3078018.

[6] Changes in Intake of Fruits and Vegetables and Weight Change in United States Men and Women Followed for Up to 24 Years: Analysis from Three Prospective Cohort Studies. Monica L. Bertoia, Kenneth J. Mukamal, Leah E. Cahill, Tao Hou, David S. Ludwig, Dariush Mozaffarian, Walter C. Willett, Frank B. Hu, Eric B. Rimm. PLoS Med. 2015 Sep; 12(9): e1001878. Published online 2015 Sep 22. doi: 10.1371/journal.pmed.1001878. Correction in: PLoS Med. 2016 Jan; 13(1): e1001956.