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Be Careful With Red Kidney Beans in The Slow Cooker

1/31/2013 2:46:38 PM

Tags: kidney beans, red kidney beans, chili, bean toxin, Robin Mather

Bowl of ChiliWhen the weather is cold and raw, good cooks turn to their crockpots to provide the long-simmered dishes that winter appetites demand. We seem to hunger naturally for the flavors of chilis and soups, stews and pot roasts.

One favorite winter dish that requires a bit of caution, however, is the big bowl of crockpot beans. Red kidney beans — commonly added to chili — can be the source of Red Kidney Bean poisoning, caused by a toxin called Phytohaemagglutin, or kidney bean lectin.

Other beans also contain the toxin, but in varying amounts. Red kidney beans have 20,000 to 70,000 heagglutinating units (hau), while white beans contain about a third as much; broad beans like favas have as little as 5 percent of the amount in red kidney beans.

This toxin can make you feel pretty crummy. Raw or undercooked beans can cause nausea, vomiting, diarrhea and abdominal discomfort within 1 to 3 hours. Recovery usually is complete within 4 hours of the symptoms’ appearance, though some people have been hospitalized.

Fully cooked or canned beans are always safe to eat. But undercooking can actually raise lectin activity. That’s why it’s best to use canned or fully pre-cooked kidney beans in crock pot recipes that call for beans.

For more information, visit the Penn State Extension explanation at


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2/3/2014 12:36:42 PM
Great point to bring about the toxin in kidney beans and other beans. But the best way to take care of the toxin is described in the excellent bean cookbook, Dried Beans & Grains (The Good Cook, Techniques & Recipes), from Time Life Books. The book explains that the toxins in large beans like kidney beans can be destroyed by bringing the beans to a boil for at least 10 minutes. The smaller legumes like lentils and the like need to be boiled for at least 2 minutes. Canned beans don't always get boiled when processed, and the can itself poses the scary danger of BPA. A few companies are now selling cooked beans in the frozen food section, probably for this reason.

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