Two food groups — beans and whole grains — that mostly enjoy a healthful reputation are being slammed both online and in a book because they contain lectins. What are lectins, and why should they be shunned?
Lectins are a group of proteins found in most plants. They’re plentiful in beans and whole grains. Lectins are also found in smaller amounts in both white and sweet potatoes, tomatoes, zucchini, carrots, berries, watermelon, nuts, coffee, chocolate, and select herbs and spices (such as peppermint, marjoram, and nutmeg).
In growing plants, along with other compounds, they serve as a defense system against invaders,
Lectins are sometimes referred to as anti-nutrients. The claim is that lectins incite a “biological warfare” within our bodies, ultimately causing weight gain, digestive maladies, elevated cholesterol, acne, arthritis, and even brain fog.
What does the research show?
Over the years, lectins have been the subject of a great deal of research; they are not newly discovered. Certain lectins can be toxic, while others have no ill health effects. Online health sensationalists and book authors paint lectins with the same brush claiming they’re all dangerous. The truth is their so-called evidence is weak and lacks peer-reviewed science to back it up.
Here’s the thing: The majority of lectin studies were done on isolated lectins and not actual foods. While it’s a fact that lectins damage the digestive tract in studies in which animals were fed raw beans or pure lectin, the reality is that we don’t consume beans that are raw. And we certainly don’t consume isolated lectin. We cook our beans and whole grains — or ferment or sprout them — before eating, which deactivates most lectins. So that’s a moot point.
In addition, few studies have been conducted on humans; rather they’ve been done on animals or in test tubes. How can book and online health gurus link lectin-containing foods to certain health maladies when no clinical trials on humans have been completed?
But when you cook dry beans — especially red kidney beans — only in a slow cooker, they may not reach a high enough temperature to break down all the lectins present. The result may be several hours of gastrointestinal upset such as nausea, vomiting, gas, and diarrhea, especially if eaten in large quantities.
Fermentation and sprouting also decreases lectin content. “Friendly bacteria” present during fermentation digests the anti-nutrients, reducing lectins by up to 95 percent.
Beans are superior sources of iron, B vitamins such as folate, magnesium, zinc, and potassium and other minerals and are an inexpensive and sustainable way to obtain protein. Whole grains, such as brown rice, quinoa, wheat, and barley, provide ample amounts of B vitamins, iron, magnesium, and selenium. Both food groups are excellent sources of dietary fiber.
While there are people who feel better when avoiding beans and whole grains, most of us can safely eat them and enjoy the myriad of ways they are prepared.
What about pricey supplements that promise to neutralize the negative effects of lectins? Don’t waste your money on these scare tactics; they’re simply not necessary.
In short: Don’t let pseudoscientists scare you away from eating legumes and whole grains. Some of the healthiest populations around the world center their diets around these two food groups.
Christine Palumbo is a Naperville, Ill.-registered dietitian nutritionist who enjoys whole grains on a daily basis and tries to fit in beans whenever possible. Find her at Christine Palumbo Nutrition on Facebook, @PalumboRD on Twitter, or Chris
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