Ask the Expert: Clearing Up Lectin Misconceptions (2024)

Ask the Expert: Clearing Up Lectin Misconceptions (1)October 2017 Issue

Ask the Expert: Clearing Up Lectin Misconceptions
By Toby Amidor, MS, RD, CDN
Today's Dietitian
Vol. 19, No. 10, P. 10

Q: I've been seeing articles and books on the health benefits of a lectin-free diet. Is there any merit to these claims?

A: Americans constantly are bombarded with misinformation, and it's especially tough to wade through the purported facts when the information is circulated by medical authorities such as physicians. Although the research on lectin, which is found primarily in nutrient-dense plant foods, is still emerging, preliminary studies have revealed potential health benefits of lectin consumption and minute evidence of harm.

The Controversy
Lectin is a carbohydrate-binding protein that can be found in varying amounts in most plants, including beans, pulses, grains, fruits and vegetables (eg, potatoes, tomatoes, sweet potatoes, zucchini, carrots, berries, watermelon), nuts, coffee, chocolate, and some herbs and spices (eg, peppermint, marjoram, nutmeg). Pulses and grains contain the highest amounts of lectin compared with other foods. Cooking destroys most of the lectin in foods and weakens its ability to bind to cells or causes it to bind to other compounds found in food.

The lectin-free diet has been popularized since cardiologist Steven Gundry, MD, FACS, FACC, released the New York Times bestseller The Plant Paradox: The Hidden Dangers in "Healthy" Foods That Cause Disease and Weight Gain in April 2017. The book promotes a lectin-free diet to treat medical conditions such as autoimmune diseases, allergies, and cancer. Supporters of the Bulletproof Diet also promote a lectin-free diet.

Gundry and other lectin-free diet promoters believe that lectin-containing foods promote inflammation, lead to weight gain, and are toxic to the body. However, there's very little research on lectin's effects on the body. A 2004 review published in Toxicon looked at the limited information regarding lectin and determined that it's an antinutritive and/or toxic substance.1 Researchers in Brazil determined that, because lectin survives digestion in the gastrointestinal (GI) tract, it can bind to the cell lining within the digestive tract and lead to a series of harmful local and systemic reactions. However, foods with high amounts of lectin, such as kidney beans, aren't eaten raw. Once soaked and cooked, the lectin content is significantly reduced and, as such, isn't a potential issue for the body. Furthermore, the commonly known health benefits of consuming whole grains and pulses, such as reduced inflammation, far outweigh any concern for the small amount of lectin found in these foods.

Although the scientific literature raises theoretical concerns about the potential toxicity of lectin, research also suggests lectin provides health benefits with regard to GI metabolism and cancer prevention. A 2016 article published in Current Protein & Peptide Science reviewed the anticancer activity seen in mushrooms in vitro and in vivo.2 Researchers concluded that lectin may have a possible role in the treatment of cancer and even could be used in antitumor drugs in the future. A study in 1993 published in the European Journal of Clinical Nutrition discussed the possible benefit of lectin to gut health, specifically due to the fact it isn't digested and can be transported across the gut wall.3 The study examined animal trials, however, and research is limited in humans.

Putting Research Into Practice
Given the strong scientific data that support the health benefits of pulses, nuts, fruits, and vegetables (ie, foods in which lectin is found), and the scarce scientific evidence available on the harmful effects of lectin, it would be nonsensical for any dietetics professional to recommend a lectin-free diet. Furthermore, because they provide a wide array of important nutrients, removing lectin-filled foods from the diet, especially over a long period of time, can lead to potential deficiencies. However, as the media and current diet culture continue to have a strong influence on consumer behavior, dietetics professionals should be prepared to answer questions about lectin and debunk the myth surrounding avoidance of lectin-containing foods. As set forth by the 2015–2020 Dietary Guidelines for Americans, RDs should promote a well-balanced, varied diet filled with whole grains, fruits, vegetables, low-fat or nonfat dairy, lean protein, and healthful fats.

— Toby Amidor, MS, RD, CDN, is founder of Toby Amidor Nutrition (http://tobyamidornutrition.com) and the author of the cookbook The Greek Yogurt Kitchen: More Than 130 Delicious, Healthy Recipes for Every Meal of the Day and the newly released The Healthy Meal Prep Cookbook. She's a nutrition expert for FoodNetwork.com and a contributor to US News Eat + Run and MensFitness.com.


References

1. Vasconcelos IM, Oliveira JT. Antinutritional properties of plant lectins. Toxicon. 2004;44(4):385-403.

2. Singh RS, Kaur HP, Kanwar JR. Mushroom lectins as promising anticancer substances. Curr Protein Pept Sci. 2016;17(8):797-807.

3. Pusztai A. Dietary lectins are metabolic signals for the gut and modulate immune and hormone functions. Eur J Clin Nutr. 1993;47(10):691-699.

Ask the Expert:  Clearing Up Lectin Misconceptions (2024)

FAQs

Is there any controversy associated with lectins? ›

While the function of lectins within the body is a point of controversy, with some experts claiming lectins can potentially cause adverse health effects like leaky gut and autoimmune issues, lectin-containing foods have important health benefits.

What cancels out lectins? ›

Active lectins are what's found in raw plants. But boiling, baking, pressure-cooking and soaking can deactivate those lectins, so they're not going to have the same effect as they would if you ate them raw. Fermentation, sprouting and removing peels and seeds can also reduce the amount of active lectin in plant foods.

What is the true truth about lectins? ›

Lectins are a family of proteins found in almost all foods, especially legumes and grains. Some people claim that lectins cause increased gut permeability and drive autoimmune diseases. While it's true that certain lectins are toxic and cause harm when consumed in excess, they're easy to get rid of through cooking.

What are the worst lectin foods? ›

These six foods are some of the worst sources of lectins in the American diet when consumed raw.
  1. Raw Kidney Beans. Red kidney beans are a great source of plant-based protein and they are a low-glycemic-index food. ...
  2. Peanuts. ...
  3. Whole Grains. ...
  4. Raw Soybeans. ...
  5. Raw Potatoes.

Are avocados high in lectins? ›

Avocado is a versatile fruit that is not only delicious but also lectin-free. It is an excellent source of healthy fats, fiber, potassium, and vitamins, making it a nutrient-dense addition to any meal.

How do you flush lectins out of your body? ›

The best ways to mitigate the toxic effects of lectins are traditional food preparation methods, which include soaking, sprouting, and fermenting grains and legumes. You can ferment flour before cooking with it. Sourdough bread and a traditional flatbread from India called dosa are both made from fermented flours.

Are eggs high in lectin? ›

Eggs are not full of lectins. Chickens raised on pasture and not fed grains or soy produce eggs that contain little to no lectins. How do lectins work? Lectins are proteins found in plants that can bind to carbohydrates.

Does vinegar get rid of lectins? ›

Reducing Lectins

Soaking grains, legumes and seeds can help reduce lectin content. The best way to do this is to submerge the food in water with 1 T. of apple cider vinegar or lemon juice and to allow the foods to soak for 4-24 hours.

Are blueberries high in lectins? ›

Lectin-free fruits include pomegranates, lemons, beets, blackberries, blueberries, apples, plums, sweet oranges, tangerines, and dates.

What are the symptoms of too much lectin? ›

The Problem With Lectins

The most publicized accounts report severe reactions in people eating even small amounts of raw or undercooked kidney beans. They contain phytohaemagglutinin, a type of lectin that can cause red blood cells to clump together. It can also produce nausea, vomiting, stomach upset, and diarrhea.

Why is lectin not good? ›

Lectins are proteins and antinutrients in plant foods. Antinutrients are compounds that can interfere with your body's ability to digest and absorb other nutrients. Legumes, like beans and lentils, have especially high amounts of lectins. Eating raw foods that contain lots of lectins can cause digestive problems.

Are bananas high in lectins? ›

If you are on a lectin friendly diet, you are also allowed to enjoy green bananas, but not ripe bananas as they contain lectins in addition to the high amount of sugar. Sorghum is a great source of fiber (resistant starch) and low in lectins in comparison to barley, brown rice, quinoa, and whole wheat.

Why is lectin bad to eat? ›

But because lectins are resistant to acidic environments, like your stomach, they're hard for your gut to break down. In some circumstances, eating lectin-containing foods might lead to nausea, vomiting, diarrhea, and bloating.

What does Dr. Gundry say about lectins? ›

According to Steven Gundry, MD, a heart surgeon based in California who is credited with the development of the lectin-free diet, lectins disrupt cell communication and increase inflammation, causing poor gut health that leads to a host of ills, including digestive problems (bloating, gas, diarrhea), weight gain and ...

Do lectins really cause leaky gut? ›

Incompletely digested proteins can elicit allergic reactions, and allergies to lectins in wheat, banana, avocado, chestnut, turnip, and corn have been reported. But allergies aren't the major problem. Lectins in uncooked foods cause leaky gut by poking holes in the layer of cells—the mucosa—lining the intestine.

References

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