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Should You Be Afraid of Lectins?

1 May, 2020 ,

We are hearing more and more about lectins and their potential negative impacts on our health. They are mentioned as being responsible for promoting weight gain, digestive disorders and the development of food sensitivities. This is why some, including Dr. Steven Gundry with his book “The Plant Paradox: The Hidden Dangers in “Healthy” Foods That Cause Disease and Weight Gain“, recommend adopting a diet that eliminates lectins.

If you’re wondering if lectins are harmful to your health, the following article will help you to examine the subject.

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To start with, what are lectins?

Lectins are a type of protein found in plants. They play a protective role against bacteria, viruses, and pathogenic fungi as well as certain predatory insects.

Lectins are found in large quantities in whole grains, legumes, nuts (peanuts and cashews), as well as vegetables, being mainly found in those of the solanaceae family such as tomatoes, peppers, potatoes and eggplants.

Are lectins harmful to health?

A negative point for lectins is that they are considered anti-nutrients because they can interfere with the absorption of certain nutrients such as calcium, iron, phosphorus and zinc.

In addition, when consumed in large quantities in their active state (in raw food), lectins could cause digestive problems in humans such as bloating and gas, but may also cause more severe symptoms such as nausea, vomiting, stomach aches and diarrhea. This is the case of a type of lectin, phytohemagglutinin, found in legumes, especially raw or undercooked red, white and black beans, which makes them toxic to humans. Fortunately though, we eat our legumes well-cooked!

In addition to digestive symptoms, some report that lectins are capable of causing inflammation, weight gain and intestinal permeability. However, there is a lack of scientific studies on humans to validate these hypotheses.

Can the lectin content of food be reduced?

As we have seen, raw beans can cause severe digestive problems, but when cooked properly, you have no reason to worry. Why is this? Because lectins are proteins so they can be broken-down by heat. By cooking your food at high temperatures, you reduce their lectin content. However, beware of slow cooking that does not allow you to reach a sufficiently high temperature of 212°F or 100°C. If you want to use this cooking method for your legumes, it is important to boil them at least 10 minutes before using the slow cooker.

The processes used to conserve and can the legumes also destroy the lectins.

Finally, fermentation would also reduce the concentration of lectins found in cereals and legumes.

In addition to this, the body can produce enzymes during digestion that break-down certain lectins.

Note that the foods richest in lectins such as legumes, potatoes, whole grains, eggplants… are all consumed cooked. Thus, eating foods rich in active lectins is rare.

On the other hand, tomatoes, rich in lectins, are very often eaten raw. However, there are no cases of adverse symptoms associated with lectins (nausea, vomiting) from the consumption of raw tomatoes in the literature. The lectins in tomatoes (lycopersicon esculentum agglutinin) should be better tolerated than the ones in raw beans.

Should you eliminate them from your diet?

Being rich in vitamins, minerals, antioxidants and fiber, fruits, vegetables, nuts, legumes and whole grains are recognized by science for their many health benefits such as: reduced risk of cardiovascular disease, promoting weight loss, a lower risk of developing type 2 diabetes, anti-inflammatory effects or even reduction in cancer rates. No wonder the diet of people in countries with the longest lifespan is mainly based on the consumption of legumes, whole grains and vegetables.

Therefore, including these foods in your diet is much more advantageous than excluding them.

In addition, some studies demonstrate the positive potential of lectins. These could:

  • act as an antioxidant, helping to protect the body
  • prevent too much variation in blood sugar by slowing down the digestion and absorption of carbohydrates.

In conclusion, removing lectin-rich foods from your diet is not an optimal solution as these foods also contain many essential nutrients for health.

If you experience symptoms, digestive or otherwise, that you think are related to the foods you eat, one of your best options is to talk to a dietitian. Giving the body what it needs is not that complicated, but when you restrict your diet too much and exclude large groups of foods, this can become a real challenge. A dietitian will help you review your diet and suggest changes to reduce your symptoms by maximizing your dietary diversity.


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Jennifer Morzier

Jennifer Morzier

Jennifer is a Registered Dietitian graduated from the University of Montreal in December 2018 and is a member of the Ordre professionnel des diététistes du Québec (OPDQ). She believes that the quality of our food choices has a direct impact on our health and energy level. Her goal? To help people improve the quality of what they put in their plates, for their better well-being and greater pleasure.

Jennifer Morzier

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