If you’ve been keeping up with nutrition trends, you might have noticed that plant foods, such as pulses and whole grains, have been the target of some serious food bashing. Typically seen as nutrient powerhouses, these foods are being accused of causing weight gain and chronic disease because they contain a protein called lectin. But does the science stack up?

 What are lectins?

Lectins are proteins found in many plant foods, including whole grains, pulses, seeds, some nuts, tomatoes, bell peppers, most fruits and potatoes. They are also found in smaller amounts in egg and dairy products. In plants, lectins are an important defense against pests. Because they cause cells to stick together, they can cause serious digestive distress if eaten in large amounts. It’s this property that has led to lectins being blamed for weight gain, inflammation, food sensitivities and chronic disease.

 The plant paradox

Much of the hubbub about lectins comes from the book The Plant Paradox. The author, Dr. Steven Gundry, claims that lectins are the source of most human diseases, and that avoiding them can cure autoimmune diseases, heart disease, weight gain, mental health problems and neurological problems. Along with this list of lofty claims, the book provides a long list of foods to eliminate in order to avoid lectins. It also includes a list of recommended supplements for people following a lectin-free diet.

What does the science say?

Lab studies vs. real life

Many of the studies looking at the negative effects of lectins have been conducted with isolated lectins in test tubes or animal models. In other words, very few studies have looked at whether lectins in food have negative effects when humans eat them. While this seems like a small distinction, it’s important to remember that the compounds found in food are never eaten in isolation. How they act in a test tube may be very different from how they act when we eat them.

 Raw kidney beans

Like many nutrition fads, the link between lectins and human health does have a grain of truth to it. When eaten in very large amounts (for example, the amount found in raw kidney beans), lectins can indeed cause vomiting and diarrhea. However, simply cooking, boiling, baking, microwaving or pressure-cooking lectin-rich foods drastically reduces the lectin content, making them safe to eat. The canning process also destroys lectins, meaning that any canned lectin-rich foods will have very little lectins left. Plus, many of the foods highest in lectins (pulses and whole grains) aren’t eaten raw to begin with!

Digestive diseases

People with digestive issues, such as Crohn’s disease or IBS, may be more sensitive to lectins. However, as is true for all foods, most healthy people should be able to eat properly-cooked lectin-containing foods without any ill effects. If you’re suffering from digestive concerns and feel that reducing the lectin content of your diet could be helpful, consider working with a registered dietitian who can help you identify trigger foods and meet your goals in a sustainable way.

The benefits of lectins

Despite recent claims that lectins can cause health issues, numerous studies show that lectin-containing pulses can have beneficial health effects, such as improving blood sugar control, lowering LDL cholesterol and decreasing blood pressure. Similar effects have been found in studies where participants consumed whole grains.

 The bottom line

The sensational claims of a lectin-free diet simply don’t stack up with the science. A lectin-free diet is restrictive and involves eliminating several foods that form the foundation of a healthful, balanced diet. By steering clear of sensational claims, you give yourself room to enjoy a variety of nutrient-dense foods that the science continues to show can help you maintain your health.

 

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Sarah Morland, RD

Registered Dietitian

Sarah (BSc, RD) is an Edmonton-based registered dietitian and blogger for Nourish Move Thrive. She believes that food should nourish both the body and soul, and that physical activity should be fun. She enjoys debunking nutrition myths and translating scientific evidence into practical advice.

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