Are beans and whole grains making us sick?

A new fad may have you wondering whether your diet is healthy…or even safe. Here’s the real deal.

“Most people have never even heard of them, but I believe lectins are the #1 Biggest Danger in the American Diet,” says the website of cardiologist (and Lectin-Shield supplement salesman) Steven Gundry, author of The Plant Paradox.

Lectins are proteins that are found in most plants. Beans and whole grains typically have more than other plants.

Gundry’s website states that you should avoid beans, seeds, grains, and more thanks to their lectins.

“Plants don’t exist solely for us to eat them,” explains David Jenkins, a professor of nutrition at the University of Toronto. “Their goal is to survive and reproduce. Lectins are just one of a whole group of compounds that act as a defense system against invaders.”

To protect the plant, says Gundry’s book jacket, lectins “incite a kind of chemical warfare in our bodies,” causing everything from digestive problems, weight gain, and high cholesterol to arthritis, brain fog, and adult acne.

“I’ve never seen anything in the major medical journals to support that,” says Jenkins. “If there were a problem, we’d know about it. Big time.”

It’s true that lectins damage the gut in studies that feed animals raw beans or pure lectin.1,2 But we cook, ferment, or sprout our beans and grains, which deactivates most lectins.3

The exception: some slow cookers and some casseroles may not reach temperatures high enough to break down all the lectins in raw beans. That can lead to lectin toxicity, especially with red kidney beans. The resulting nausea, vomiting, and diarrhea can last for several hours.

To be safe, soak dry beans in water for at least five hours, pour off the water, and boil briskly in fresh water for at least 10 minutes. Then finish cooking them on the stove or in a slow cooker. Canned beans are already cooked.

Don’t let lectins scare you away. “Some of the healthiest populations around the world eat the most beans and whole grains,” says Jenkins.

Bottom Line: Thoroughly cook, don’t avoid, beans and whole grains.

References

1Gastroenterology 82: 838, 1982.
2J. Agric. Food Chem. 39: 1627, 1991.
3J. Agric. Food Chem. 50: 6592, 2002.

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25 Replies to “Are beans and whole grains making us sick?”

  1. Thank you for this clarification. I have watched the Gundry video and was very confused. Now I understand more about the issue he makes and will continue to eat beans.

  2. Does that mean we should thoroughly cook all whole grains? I’ve been eating raw oats, for example, thinking they were good for you? (Or, I guess the Bob’s Red Mill oats are “kiln toasted”….)

  3. Thanks for the great article.

    What are the implications of this for whole grains like oatmeal, especially the types where they are only microwaved for a few minutes?

  4. That’s good news. But what about seeds? Sunflower, pumpkin and sesame seeds are great snacking foods. Are they safe to eat?

    1. Yes, while they may have some lectins, there’s no evidence that lectins in seeds and nuts are harmful to consume. The content may be too low to do anything or they may be beneficial. There is emerging evidence that a variety of different lectins are good for us.

  5. Why pour off the soaking water? I always season the water the beans/legumes are soaking in–at the beginning of the soak–& then cook them in same water. The cooking should kill off/deactivate whatever bacteria/lectins might be lurking, right? (And I always WASH the beans first in clear water, before pouring in the soaking water.)

    Thanks for any wisdom you have on this!

    1. The lectins do probably break down in the soaking water, but this is just a conservative approach to lower exposure to lectins that may not get deactivated.

  6. Best thing I did six years ago was adopt the Primal/Paleo diet as a way of life. I am 62 years old, have body fat percentage of 13% and excellent blood lipid profile and other bio markers. So no “healthy whole grains” or beans for me. My doctor who does the annual physical loves what I am doing (I am not sure he completely understands it), but every year says “whatever it is you are doing, keep doing it”.

    1. That how my asthma disappeared by adopting a Primal/Paleo diet. Beans and grains cause too much gastric upset for me plus they seem to be weight gainers.

  7. Appreciate this article. Beans have been eaten for centuries. One needs to cook completely! Thank you for clarification.

  8. Are beans from a can considered “cooked” if they haven’t been heated up, and just added to a salad? Can I use the liquid in the can? This article uses scare tactics and doesn’t give me enough information.

    1. Hi Caroline,

      Canned beans are considered cooked (see above) and won’t cause any issues with lectins. The liquid in the canned beans is fine to consume.

  9. Thank you for publishing an article on this. Dr. Jenkins, however, only seemed to be referring to current accepted knowledge and Dr. Gundy seemed to be referring to a newer understanding (based on his own research, which I agree may be questionable). So while I appreciate the advice to cook beans well, I still am unsure what is actually true. Nutrition science keeps changing and I would certainly like some better information. Just because Gundy’s info is not the current medical gospel doesn’t make it wrong (or right either.) I know Nutrition Action doesn’t usually do it’s own research, but I sure wish you did. Is there any scientific studies of this issue currently being carried out?

    Thank you.

    1. Gundry claims to have published extensive research on this, but he hasn’t. There’s also very little current research on the potential harms of lectins. Nearly all the research was done between the 1970s and 1990s. There is, however, quite a bit of current research on the potential benefits of specific lectins that are being studied for anti-tumor, anti-inflammatory effects and more.

  10. This is curious.I have never come across an advise against consumption of legumes or whole grains in the scientific literature. But,I agree with Jenkin’s last remark.

  11. I can’t imagine why people would want to consume that salty slimey liquid in canned beans. And doesn’t it contain the disolved sugars that cause gas? I am 75 and don’t have gas problems as long as I rinse beans well.

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